CHAPTER B2 LUMBER: USE IN CONSTRUCTION This is the most technical chapter in the entire course. But don t let that scare you. Look at it as a challenge. Every time you acquire more knowledge it will help you do your job better you become more valuable. The more things you can do that others can t, the more likely you will satisfy your customers keep them coming back. One group of customers you want to satisfy are those building or remodelling homes. Their business represents major building materials purchases. This customer can be an individual homeowner, or a builder who builds one to ten homes a year, or a builder who builds or remodels many homes. These people are often looking for technical advice, such as what size floor joists to use, built-up beam size, window header or lintel size, etc. Sometimes this information is provided all the customer needs is someone with a little understing of design principles. A caution right here. Never design structural members unless you are a qualified engineer. It is foolish to risk the liability associated with guessing at structural sizes. If you don t know what size, species, spacing, etc., is required, do not offer a guess. Refer the problem to a qualified engineer. You can successfully recommend structural member sizes from tables that are provided by building codes, associations, or other qualified agencies if you know how to read them. That s part of what this chapter is about. Reading tables, then practicing them. You ll also get a basic background in design considerations to go along with your table reading abilities. You also will read about quantities for ordering lumber, calculating board feet coverage tables that help you in estimating. This is more of a reference chapter than a learning chapter. There is material you ll probably use over over if you work with building materials used in homes. This chapter s primary purpose is to help you learn to read span tables. The tables in this chapter are valid, but be reminded that codes change the tables shown here may not be appropriate for all regions. You must locate obtain current tables that are used in your local area. When you obtain tables from your local or provincial building code office you will find them similar to those in this chapter, in which case you should have no trouble understing them. The tables in this chapter are meant to be accurate useful, but CRHA the author assume no responsibility for any injury, loss, or damage however caused, arising from use of any table or information provided in this course. CHAPTER OVERVIEW This chapter is broken into a number of sections to allow you to develop an understing of the basis of Canadian span tables to develop your ability to read span tables effectively. The sections that follow include: 1. Background to Canadian code requirements. 2. An overview of the wood material design strength requirements. 3. An overview of the loads used in designing various structural members. 4. Span tables for a number of end uses such as floor, ceiling roof joists, roof rafters, built-up floor beams headers over openings, etc.
To be able to read span tables effectively there are three background pieces of information that need be considered. 1. The strength of the material. 2. The loads that are going to be applied to the material. 3. The construction details that are to be used. Typically, the solution is not identifying any one of the above then simply selecting the size of member that you are able to use, but frequently involves a solution where you consider two or three options, then select the best solution for your customer. For example, a 2x8 of a grade that is not commonly stocked might provide the span that your customer wants. However, to do this you would have to make a special order which extends delivery time likely increases cost. It is likely better for you to recommend a larger size of a grade that you have in stock. How do you find the span table criteria? There are several sources such as the various grading agencies regional lumber manufacturing associations the national association, Canadian Wood Council. However, the building criteria published by all of these agencies are based on requirements contained in Part 9, Housing Small Buildings of the National Building Code of Canada (NBCC). The NBCC is generally adopted by the various jurisdictions throughout Canada. However, be aware that some jurisdictions deviate from NBCC. You should be aware that not all jurisdictions adopt the latest edition of NBCC in a timely manner. BACKGROUND TO CANADIAN CODE REQUIREMENTS An effort has been made to stardize building codes across Canada so that builders don t have to build differently every time they cross into a new government jurisdiction. Changing building methods creates additional costs confusion. The NBCC has evolved as the model Canadian building code. That is, a code that has been well thought out put together is available for provinces or local governments to adopt so they don t have to create their own. (We re not including mechanical, plumbing, or electrical codes). This building code ( others for mechanical, plumbing electrical) is prepared under the rules procedures of the Canadian Commission on Building Fire Codes. The overall code consists of nine parts includes two parts that directly affect the span tables that you will be using Part 4 Structural Design Part 9, Housing Small Buildings. Part 4 identifies the loads that are to be used in the design process also specifies the stards that provide the design requirements for the structural materials. For example, the design basis for buildings structural members made of wood shall conform to CSA O86.1, Engineering Design in Wood (Limit States Design). Part 9 identifies the criteria that are relevant to housing small buildings. As the NBCC is the Canadian model code it best fits our needs for this course. For more complete information information on how to obtain the entire code book applicable in your area/jurisdiction contact your local agency responsible for issuing building permits. More comments on the NBCC building codes in general. The formal requirements found in the NBCC ( related material specific stards) are specified using SI metric terminology. Where construction practices use the Canadian Imperial measurement system, conversions need to be made. This means that some of the converted values look funny (e.g. a 2.0 kpa snow load is equivalent to 41.8 psf.). In addition, the requirements of Canadian building codes are developed on a basis that differs from that of other countries. Span tables developed for use in Canada differ from span tables developed for use in the US, even though the same species grade of Canadian lumber is going to be used. One additional caution. Many areas, particularly rural areas, may not be under any building code. Good building practice would usually dictate that you want to construct homes with at least the minimums found in the codes. So even if you don t have to follow a building code, it s a good idea to use it for reference. With the above as reference, let us continue by looking at the terms you ll be seeing in the various tables. For the most part it is not necessary to underst all the terms. Usually you could go right to the appropriate table find what you need. You ll communicate with your customers better about required structural
member sizes, however, if you have a basic understing of these terms. So give it a shot. FLOOR JOISTS AND TRUSSED ROOF Structural members, of course, carry the weight of the building materials building contents ultimately to the ground. So a series of bearing walls, joists, rafters, (or trusses) headers, girders, etc., is designed to do that. The amount of weight that lumber can carry is dependent on its strength. The strength of lumber varies with species, as well as within species. Its strength is also dependent on the amount kind of defects. This is reflected in the grade given to it by the lumber grader (or machine grader if MSR lumber). These strength values are further adjusted to reflect lumber size, 2x4 or 2x10 for example what it is being used for: a floor joist, a rafter, etc. Also whether it is being used as a single piece, such as a beam, or with a group, such as floor ceiling joists, or rafters. This sounds complicated but the situations just described are taken care of when using the span tables. FLOOR JOISTS, CEILING JOISTS AND RAFTERS MATERIAL DESIGN PROPERTIES The table on the following page is typical of the tables identifying specified strengths for visually stress-graded lumber. The table is for structural joists planks of lumber as appropriate for use in Canada. Similar tables are available for the other grades of stud, light framing, beams stringers, posts timbers MSR (Machine Stress Rated) lumber. You will note that the value for each property has not been listed in the table. The table has been presented in this way as, in the design process, the value needs to be modified for a number of factors such as: load duration, service condition, treatment, type of construction, size, etc. Span tables incorporate these factors where appropriate. So, when you read span tables it is important that you also read the notes etc., to ensure that the spans reflect the conditions under which the building is going to be built. In addition, be aware that spans for use in Canada are not the same as for spans in other countries that spans for grade are the same as for grade. In other words, spans developed for use in the US are not the same as those for use in Canada.
SPECIFIED STRENGTHS AND MODULUS OF ELASTICITY FOR STRUCTURAL JOISTS AND PLANKS OF LUMBER (MPa) Bending at extreme fibre Compression Species Identification Longitudinal shear Perpendicular to grain Tension parallel to grain Modulus of elasticity Parallel Grade to grain f b f v f c f cp f t E SS xxx xxx xxx xxx xxx xxx DFir-L / xxx xxx No. 3 xxx A specified strength or modulus of elasticity will xxx SS xxx be listed (shown as xxx) for each species group, xxx Hem-Fir No.1/ xxx grade property. Beware that in Canada the xxx S-P-F No. 3 xxx numerical value for grades are xxx SS xxx equal. The values are not identified in this table xxx No.1/ xxx xxx as a number of modification factors are applied to No. 3 xxx xxx the value in the overall design process. SS xxx xxx Northern No.1/ xxx xxx No. 3 xxx xxx xxx xxx xxx xxx Notes: Tabulated values are based on the following stard conditions: (a) 286 mm larger dimension (b) dry service conditions (c) stard term duration of load COMMON STRESS TYPES There are several types of stresses that develop in loaded members. In the design process the designer checks that none of the specified strengths are exceeded when a load is applied to the member. However, generally the importance of the type of stress is dependant on how the member is being used. For example, rafters will usually fail first, by bending too much breaking. Therefore, the f b value is usually the limiting factor in rafter design. The rest of the stresses are present but the lumber is usually strong enough to withst them. At the top edge the lumber wants to get shorter or compress. This stress is called compression parallel to grain, it is frequently referred to simply as compression. It s the tendency to push together or shorten. Along the bottom the lumber wants to lengthen, or pull apart. This stress is called tension. The nearer to the centre you get, the less bending stress there is. Right at the middle there is no bending stress. This middle is sometimes called the neutral axis (this middle is where longitudinal (or horizontal) shear is the greatest, but right now we are discussing extreme fibre stress in bending). We will now look at each of the stress types that develop in members under load. BENDING MEMBERS Extreme Fibre Stress In Bending - f b Three primary types of stresses are introduced into a member that bends under load. The greatest (or extreme) stress occurs along the very top edge bottom edge of the lumber.
Modulus of Elasticity - MOE or E The limiting factor for floor ceiling joists ( many beams) is frequently their elasticity. This means that they will bend enough to cause problems in the building, before they get enough weight on them to break. The reason this is a problem for floor ceiling joists is that they are carrying drywall. If the ceiling sags enough the joints will come apart, nails will pop problems will occur. The floor joists may not have drywall directly applied to them, but if they sag so do the walls on top of them creating the same problems. The amount of sag or deflection is set by the building code. Generally the deflection limit for floor joists is set at 1/360 of the span (usually stated on the span table). That is a maximum sag of 1" for every 360" (30') of joist length. To see what the actual allowed deflection for any span is, convert the span length into inches then divide by 360. For example, if a joist has a span of 14', then 14' = 168". Divided by 360 = 0.467 or just less than 1 / 2". That doesn't mean the joist will sag 0.467, but that is the maximum it can deflect, by code. The joist is likely not stretched out to its maximum span, is probably not the lowest possible grade or species piece in the world so we ll never have the total designed load on this joist at its weakest point (centre span). Ceiling joists are usually allowed a little more deflection by code as the ceiling joists do not carry bearing walls. A common amount is 1/240th of the span. (Using the 14' span as an example: 14' = 168". Divided by 240 = 0.700", or almost 3 / 4". Rafter tables allow even more deflection if the underside of the rafter is not carrying drywall ( it usually doesn t). Usually it is 1/180th of the rafter span. restriction of deflection use the f b value as the limiting factor. The modulus of elasticity E is a measure of the elasticity of the material. In the SI system it is expressed in MPa where as in the Canadian Imperial measurement system it is expressed in pounds per square inch (psi). E value is often shortened by dividing by one million so that an E value of 1,500,000 is often called 1.5E. OTHER STRESS TYPES The modulus of elasticity (E) the extreme fibre stress in bending (f b ) are the two design parameters covered so far. They are the major controlling factors in joist rafter spans. Let s now look at the remaining main stress types. Fibre Stress in Tension - f t This is important in a post when forces are trying to pull it apart. Except for prefabricated trusses the f t value rarely is ever a controlling factor in house building. Compression Parallel to Grain - f c This is the more normal loading of a post, column, stud, etc. Rarely is this a problem in normal house construction since most lumber is very strong in resisting compression. Compression Perpendicular to Grain - f cp Wherever the floor joist, ceiling joist, beam, etc., rests on a support, the weights tend to crush, or compress, the fibres at the bearing point. The bearing area has to be large enough so this doesn t happen. The building codes take care of this by setting minimum bearings for the various members. You don t have to worry about this, just read the tables properly they ll stop you from using members that break too soon or deflect too much. One reason for knowing about this is you may use joists in an agricultural or commercial building where drywall nail popping opening of corners is not a problem. You can ignore the
Minimum Bearing Minimum bearing for wood floor ceiling joists rafters is typically 1 1 / 2" for beams is 3 1 / 2". If you follow these minimums in house construction, compression perpendicular to grain probably will never enter your mind again! Longitudinal (Horizontal) Shear - f v This is where the wood fibres tend to slide over themselves horizontally right at the top to bottom mid-point of a member loaded in bending (refer to the figure as related to the extreme fibre stress in bending discussion). This is not usually a problem either, except possibly in short, heavily loaded beams, that are quite deep. For practical purposes the only stresses are typically of concern in common house construction are E f b. The rest are included for background information to help you underst other information you may come across. LOADS When engineers develop span tables they decide what will be the maximum load the various members may have to carry. There are two primary kinds of loads: dead live loads. DEAD LOADS Dead loads are weights of building materials objects installed in or on the structure. Walls, ceilings, roofs, furnaces, etc. Dead loads can be calculated right down to the ounce, but for design purposes there are several stard dead loads. For floors ceilings, it s common to use 10 pounds per square foot (psf) for roofs, 7 psf is common. This information is generally noted on the tables. LIVE LOADS Live loads are all loads that are not dead loads. For the most part it includes people furniture. Things that come go are fairly easy to move. These loads are impossible to figure accurately. You don t know how many people may live in the house, or st in the same area at one time, or the amount kind of furniture, etc. But there are numbers reflecting the highest probable live loads for different conditions. These live loads are found in building codes. For example, all rooms in a house except sleeping rooms would have a live load of 1.9 kpa (40 psf). Sleeping rooms attics with limited storage: 1.4 kpa (30 psf). Auditoriums have a common live load of 4.8 kpa (100 psf). You will need to use the correct local code requirements. Other live loads that are important are snow loads, wind loads in some regions earthquake loads. Snow loads affect several components of the building structure. You ll most likely have a choice in snow loads of 1.0 to 4.0 kpa (20.9 psf to 83.5 psf) or heavier. The one to pick depends on the conditions in your area. If you have a building official ask them which one to use. TOTAL LOADS When reading span tables for house construction the normal live dead loads are already added together. If your situation is the same as described in the heading or footers of the tables go ahead use them. Sometimes your specific situation may differ. If your loads are heavier or more restrictions apply, you cannot use the tables. You should then use a qualified engineer or architect. AN EXAMPLE - A 28' WIDE HOUSE We are now going to work through a number of tables by first introducing a table then using a number of examples of how you find the size of framing members for a make-believe 28' wide house. We will assume that there is a bearing wall in the centre that the clear span will be 14'. We ll look at the table headings describe the terms in those tables, so it ll take a while. Once you know the species grade of wood you ll be using, you need to find its span values. How do you know the species grade you ll be using? For this lesson we ll give you that information. However on the job you ll simply know, or ask, what species grade of lumber you stock in 2x8 or 2x10, which is the common
floor joist sizes. Or what species grade you stock in 2x6, which is the common ceiling joist rafter size. Of course you don t know that those sizes will work for your particular situation, that s why you should look it up in the tables. For this review we will be using information similar to that found in the NBCC s Part 9 Housing Small Buildings Canadian Wood Council s The Span Book which is a supplement to the wood joist, rafter beam spans found in NBCC. As before, you should determine what information is acceptable to the building authority in your area. Two additional points. The tables in this chapter present information applicable to No. 2 grades of Structural Light Framing (2x4) Structural Joists Planks (2x5 wider) categories of lumber. NBCC, the CWC span book the code in your jurisdiction provide spans for several other grades such as: Select Structural, No. 3, Stud, Construction, etc. In addition, the chapter provides spans for a limited number of snow loads. Again NBCC, the CWC span book the code of your jurisdiction provide spans for a broader range of snow loads. Several figures much of the tabular information in this chapter is based on information generally available from the Canadian Wood Council. FLOOR JOISTS NBCC provides tables listing maximum spans for floor joists for general cases as well as for special cases. The table on the following page provides the information for the general cases of: with strapping, with bridging with strapping bridging (see column headings) the table following this table provides the information for the special cases of: joists with ceilings attached to wood furring, without bridging with bridging joists with concrete topping, with or without bridging. a number of construction practices that reduce vibration as a result, improves floor performance. Before referring to the span tables let s look at what we mean by joist span at some of the various construction practices. Joist span is the clear distance between supports. Strapping is a piece of lumber nailed to the bottom of the joists. The NBCC requires that the minimum strap be a 1x3 located at not more than 2.1 m (6'-10") from each support or other rows of strapping fastened at the ends to sill or header. Panel-type ceiling finish attached directly to the joists may be considered as equivalent in some jurisdictions. Bridging consists of solid blocking (2x joist depth) or cross-bridging (1x3 or 2x2 minimum) located not more than 2.1 m (6'-10") from each support or other rows of bridging. Floors constructed without strapping, bridging, etc., tend to be bouncy. This does not mean that they will collapse but that they will bounce as a person walks on the floor. To minimize bouncy floors (or more technically referred to as vibration) the NBCC requires that the design of floor spans consider strength, deflection vibration. As vibration is considered in the Canadian design solution, the NBCC introduced
Strapping bridging is where both are combined on the same floor. Minimum 1x3 or 2x2 cross bridging (or 2x joist depth solid blocking) located not more than 2.1 m (6'-10") from each support or other rows of bridging, together with strapping. For increased stiffness, additional rows of strapping or bridging may be used. Where more than one row of strapping or bridging is used, greater stiffness results from placement near the centre of the floor. Floor joists with ceilings attached to wood furring, no bridging relies on the furring gypsum board to stiffen the floor above. The minimum thickness of gypsum board sizes of furring strips are shown on the figure below. Where bridging is applied in combination with the above, it should meet the bridging requirements described earlier. FLOOR JOISTS EXAMPLE PROBLEMS Now let s have a look at reading the floor span tables. For all examples assume (unless the chapter asks you to consider something different) that your store stocks a complete range of sizes of grade S-P-F. MAXIMUM SPANS FOR FLOOR JOISTS: GENERAL CASES Maximum Span (ft.-in.) With Strapping With Bridging With Strapping Bridging Species Joist Joist Spacing (in.) Joist Spacing (in.) Joist Spacing (in.) Group DFir-L Hem-Fir S-P-F Northern Species Grade Notes: Size 12 16 24 12 16 24 12 16 24 2x6 10-2 9-7 8-7 10-10 9-10 8-7 10-10 9-10 8-7 2x8 12-2 11-7 11-0 13-1 12-4 11-3 13-9 12-10 11-3 2x10 14-4 13-8 13-0 15-3 14-4 13-6 15-10 14-10 13-10 2x12 16-5 15-7 14-10 17-2 16-2 15-3 17-10 16-7 15-6 2x6 10-2 9-7 8-7 10-10 9-10 8-7 10-10 9-10 8-7 2x8 12-2 11-7 11-0 13-1 12-4 11-3 13-9 12-10 11-3 2x10 14-4 13-8 13-0 15-3 14-4 13-6 15-10 14-10 13-10 2x12 16-5 15-7 14-10 17-2 16-2 15-3 17-10 16-7 15-6 2x6 9-7 8-11 8-2 10-4 9-4 8-2 10-4 9-4 8-2 2x8 11-7 11-0 10-6 12-5 11-9 10-9 13-1 12-2 10-9 2x10 13-8 13-0 12-4 14-6 13-8 12-10 15-1 14-1 13-2 2x12 15-7 14-10 14-1 16-4 15-5 14-6 17-0 15-10 14-9 2x6 8-3 7-8 7-1 9-3 8-5 7-5 9-4 8-5 7-5 2x8 10-6 10-0 9-4 11-3 10-7 9-8 11-10 11-0 9-8 2x10 12-4 11-9 11-2 13-1 12-4 11-7 13-8 12-9 11-10 2x12 14-1 13-5 12-9 14-9 13-11 13-1 15-4 14-4 13-4 (a) Nailed 5 / 8" subfloor (b) Live Load = 40 psf (c) Dead Load = 10 psf (d) Deflection = Span/360 (e) Spans include consideration of vibration criteria.
Example Problem 1 What is the maximum floor joist span for a 2x8 spaced 16" o/c when built using strapping only? Solution: (Find the information in the tables as we go along.) 1. Find the table containing the construction detail to be used. The appropriate table is Maximum Spans for Floor Joists: General Cases. 2. Review the notes to ensure that the table is based on the criteria that is appropriate. 3. Find the row dealing with S-P-F species, the row dealing with grade the row for 2x8. 4. Find the column dealing with with strapping the column dealing with a joist spacing 16" o/c. 5. Read the span where the row column intersect i.e. 11'-0". Great! Example Problem 2 What is the maximum floor joist span for a 2x8 spaced 16" o/c when built using bridging only? When built with strapping bridging? Solution: This is an extension of the first problem. The table row is the same for both of the construction details. The only change is the column. Therefore for Part 1: 1. Find the column dealing with with bridging the column dealing with a joist spacing 16" o/c. 2. Read the span where the row column intersect i.e. 11'-9". for Part 2 of the question: 3. Find the column dealing with with strapping bridging the column dealing with a joist spacing 16" o/c. 4. Read the span where the row column intersect i.e. 12'-2" Spend a bit of time examining the table. You will note that if we had exactly the same conditions as in Example Problem 1 2 except that the joist spacing is 24" o/c rather than 16" o/c the maximum spans would be 10'-6" with strapping, 10'-9" with bridging 10'-9" with strapping bridging. Yes! That is right! For this size grade of joist under this particular set of loads construction details, there is no real advantage in building with both strapping bridging. Example Problem 3 Now let s have a problem using our mythical 28' wide house having clear spans of 14'. Your customer wants to know the size of lumber that should be used for the 14' span. Solution. Continue to use the Maximum Spans for Floor Joists General Cases table. 1. Ask your customer some questions to be sure that the Notes to the table apply. In other words, additional or unusual loads are not going to be part of the building plans. 2. Find the row dealing with S-P-F species the row dealing with grade. Now all spans exceeding 14'-0" are appropriate. 3. You now should try to zero in on the type of construction that your customer would prefer to use. For example, all of the 2x12 spans exceed the 14'-0" required some of the 2x10 spans also exceed the 14'-0". 4. Your customer will likely want to use the smaller size. So, you should identify that a S-P-F, grade, 2x10 will meet the 14'-0" required span using the following construction details: with bridging 12" o/c joist spacing (14'-6"), with strapping bridging 12" o/c joist spacing (15'-1") with strapping bridging 16" o/c joist spacing (14'-1"). Your customer will likely be impressed with your advice. You have identified some options from an overall cost effective point of view it is likely that the third option (with strapping bridging 16" o/c joist spacing (14'-1") will be selected.
Example Problem 4 Now let s assume your customer asks you if the floor of the second story can be built differently? Solution: As this is the second floor the ceiling underneath will be finished. Therefore, 1. Select the table reflecting the construction detail to be used. The appropriate table is Maximum Spans for Floor Joists: Special Cases. 2. Review the notes to ensure that the table is based on the criteria that is appropriate. 3. Find the row dealing with S-P-F species, the row dealing with grade the row for 2x10. In this row you will identify four construction details (not including the concrete topping solutions) meeting your customers needs, i.e. 14'-11", 14'-1", 16'-4" 15'-7". Again you have provided your customer a number of solutions with the most cost effective one likely being the solution using 16" o/c joist spacing without bridging (14'-1"). CEILING JOISTS Spans for ceiling joists where the attic is not accessible by a stairway are the easiest to deal with as there is only the dead weight of the joists, ceiling material insulation to deal with. As there is no live load the dead load is constant these joist tables only have one span per combination of species / grade / size / joist spacing. MAXIMUM SPANS FOR CEILING JOISTS (Attic not Accessible by a Stairway) Maximum Span (ft.-in.) Species Grade Joist Joist Spacing (in.) Group Size 12 16 24 2x4 10-9 9-9 8-6 DFir-L 2x6 16-10 15-4 13-5 2x8 22-2 20-2 17-7 2x10 28-4 25-9 22-6 2x4 10-9 9-9 8-6 Hem-Fir 2x6 16-10 15-4 13-5 2x8 22-2 20-2 17-7 2x10 28-4 25-9 22-6 2x4 10-3 9-3 8-1 S-P-F 2x6 16-1 14-7 12-9 2x8 21-1 19-2 16-9 2x10 27-0 24-6 21-5 2x4 9-3 8-5 7-4 Northern 2x6 14-6 13-2 11-6 Species 2x8 19-1 17-4 15-2 2x10 24-4 22-2 19-4 Notes: (a) Attic not accessible by a stairway (b) Deflection = Span/360 MAXIMUM SPANS FOR FLOOR JOISTS: SPECIAL CASES Maximum Span (ft.-in.) Joists with Ceilings Attached to Wood Furring Joists with Concrete Topping Without Bridging With Bridging With or Without Bridging Species Joist Joist Spacing (in.) Joist Spacing (in.) Joist Spacing (in.) Grade Group Size 12 16 24 12 16 24 12 16 24 2x6 10-10 9-10 8-7 10-10 9-10 8-7 10-10 9-10 8-5 DFir-L 2x8 13-4 12-7 11-3 14-2 12-11 11-3 14-2 12-6 10-2 2x10 15-8 14-9 13-6 17-2 16-4 14-2 17-8 15-3 12-6 2x12 17-10 16-10 15-4 19-5 18-6 16-5 20-6 17-9 14-6 2x6 10-10 9-10 8-7 10-10 9-10 8-7 10-10 9-10 8-7 Hem-Fir 2x8 13-4 12-7 11-3 14-2 12-11 11-3 14-2 12-11 10-8 2x10 15-8 14-9 13-6 17-2 16-4 14-5 18-2 16-0 13-1 2x12 17-10 16-10 15-4 19-5 18-6 17-3 21-6 18-7 15-2 2x6 10-4 9-4 8-2 10-4 9-4 8-2 10-4 9-4 8-2 S-P-F 2x8 12-8 11-11 10-9 13-6 12-4 10-9 13-6 12-4 10-9 2x10 14-11 14-1 12-10 16-4 15-7 13-9 17-3 15-8 13-7 2x12 17-0 16-0 14-7 18-6 17-7 16-7 20-5 19-1 15-9 2x6 9-4 8-5 7-5 9-4 8-5 7-5 9-4 8-5 7-4 Northern 2x8 11-6 10-10 9-8 12-3 11-1 9-8 12-3 10-11 8-11 Species 2x10 13-6 12-8 11-7 14-9 14-1 12-4 15-4 13-4 10-10 2x12 15-4 14-5 13-2 16-9 15-11 14-4 17-10 15-5 12-7 Notes: (a) Nailed 5 / 8" subfloor (b) Live Load = 40 psf (c) Dead Load = 10 psf (d) Dead load of concrete topping = 20 psf (1 1 / 4" to 2" of concrete) (e) Deflection = Span / 360 (f) Spans include consideration of vibration criteria.
Example Problem 5 What size of ceiling joist should be used for our 28' wide house where the ceiling joist clear span is 14' is attic is not accessible by a stairway? Solution: 1. Select the appropriate table ( Maximum Spans for Ceiling Joists ) check the notes re attic accessibility. 2. Find the row dealing with S-P-F species, the row dealing with grade. You now recognize that several sizes joists spacings will meet the span requirements. As the other elements in the house are at 16" o/c it will likely be the preferred spacing. This works as a 2x6 at 16" o/c spans 14'-7" which is greater than the needed 14'. ROOF JOISTS AND RAFTERS Roof joists (where a ceiling is applied i.e. a flat roof, cathedral ceiling, etc.) rafters (no finish applied to the underside of the rafter i.e. an unfinished attic, etc.) are more complicated than the previous members we have looked at as we now must consider the affect of snow. From a simple point of view the span tables are no more complicated to read except you must make sure you are referring to the column that identifies the snow load requirement for your area. You should contact your local building official to identify what snow load is applicable in your area. Or better yet, what snow loads are applicable in the areas that your store serves. For example, in mountainous areas, or in areas where a boundary exists between two snow load requirements, snow loads may vary greatly even though the distances between the local areas may be small. In addition to the snow load issue we have the sloping length issue. Roof rafters possibly roof joists, are sloped. Span tables reflect the clear distance between supports. So, the clear span needs to be converted from the horizontal span to the sloping distance plus the bearing lengths, overhangs, etc. Fortunately, this is not difficult but does require you to make some additional calculations. The table below provides you with the conversion factors. CONVERSION FACTORS FOR SLOPING JOISTS/RAFTERS Slope (in 12) Slope Factor Slope (in 12) Slope Factor 3 1.031 10 1.302 4 1.054 11 1.357 5 1.083 12 1.414 6 1.118 13 1.474 7 1.158 14 1.537 8 1.202 15 1.601 9 1.250 16 1.667 How are these factors applied? Assume the horizontal span is 14' the slope is 4:12, then, from the above conversion factor table, the slope factor is 1.054 the sloping length is 14.76' (14 x 1.054). If the slope is 10:12 then the sloping length is 18.29' (14 x 1.302). Now let s look at some roof joists rafter tables. NBCC others publish roof joists rafters tables for a number snow load levels. This chapter will use only three different levels. And the differences between the levels are fairly large. So, again it is important that you obtain tables reflecting the snow loads in your area, otherwise you may be advising your customers to use spans that are overly safe, or more importantly, spans that are not safe. You certainly don t want to get the reputation that your recommendations cost too much or do not reflect the needs of your area. Now let s look at the roof span tables. Roof Joists Example Problem 6 Assume you are in an area with a snow load of 20.9 psf. What is the maximum span for a S-P-F grade 2x10 at 24" o/c? Solution: 1. Find the table containing the relevant information. Maximum Spans for Roof Joists.
MAXIMUM SPANS FOR ROOF JOISTS Maximum Span (ft.-in.) Roof Snow Load 20.9 psf (1.0 kpa) Roof Snow Load 41.8 psf (2.0 kpa) Roof Snow Load 62.7 psf (3.0 kpa) Roof Snow Load 83.5 psf (4.0 kpa) Species Joist Joist Spacing (in.) Joist Spacing (in.) Joist Spacing (in.) Joist Spacing (in.) Grade Group Size 12 16 24 12 16 24 12 16 24 12 16 24 2x4 8-6 7-9 6-9 6-9 6-2 5-4 5-11 5-4 4-8 5-4 4-10 4-3 2x6 13-5 12-2 10-8 10-8 9-8 8-5 9-3 8-5 7-4 8-5 7-8 6-8 DFir-L 2x8 17-7 16-0 14-0 14-0 12-8 11-1 12-2 11-1 9-6 11-1 10-1 8-5 2x10 22-6 20-5 17-10 17-10 16-2 13-10 15-7 14-2 11-8 14-2 12-7 10-3 Hem-Fir S-P-F Northern Species Notes: 2x12 27-4 24-10 21-0 21-9 19-8 16-1 19-0 16-7 13-6 16-10 14-7 11-11 2x4 8-6 7-9 6-9 6-9 6-2 5-4 5-11 5-4 4-8 5-4 4-10 4-3 2x6 13-5 12-2 10-8 10-8 9-8 8-5 9-3 8-5 7-4 8-5 7-8 6-8 2x8 17-7 16-0 14-0 14-0 12-8 11-1 12-2 11-1 9-8 11-1 10-1 8-9 2x10 22-6 20-5 17-10 17-10 16-2 14-2 15-7 14-2 12-3 14-2 12-10 10-9 2x12 27-4 24-10 21-9 21-9 19-9 16-10 19-0 17-3 14-2 17-3 15-3 12-6 2x4 8-1 7-4 6-5 6-5 5-10 5-1 5-7 5-1 4-6 5-1 4-8 4-1 2x6 12-9 11-7 10-1 10-1 9-2 8-0 8-10 8-0 7-0 8-0 7-4 6-5 2x8 16-9 15-3 13-4 13-4 12-1 10-7 11-7 10-7 9-3 10-7 9-7 8-5 2x10 21-5 19-5 17-0 17-0 15-5 13-6 14-10 13-6 11-9 13-6 12-3 10-8 2x12 26-1 23-8 20-8 20-8 18-9 16-5 18-1 16-5 14-4 16-5 14-11 12-11 2x4 7-4 6-8 5-10 5-10 5-3 4-7 5-1 4-7 4-0 4-7 4-2 3-8 2x6 11-6 10-6 9-2 9-2 8-4 7-3 8-0 7-3 6-4 7-3 6-7 5-9 2x8 15-2 13-9 12-0 12-0 10-11 9-6 10-6 9-6 8-4 9-6 8-8 7-4 2x10 19-4 17-7 15-4 15-4 13-11 12-1 13-5 12-2 10-2 12-2 10-11 8-11 2x12 23-6 21-5 18-4 18-8 17-0 14-0 16-4 14-5 11-9 14-8 12-8 10-4 (a) Dead Load = 10 psf (b) Deflection = Span / 360 2. Review the notes to ensure that the table is based on the criteria that is appropriate. 3. Find the row dealing with S-P-F species, the row dealing with grade the row for 2x10. 4. Find the column dealing with roof snow load 20.9 psf the column for a joist spacing 24" o/c. 5. Read the span where the row column intersect i.e. 17'-0". Remember this is the clear span. A longer length of lumber will be required to provide for bearing ( overhang if required). Example Problem 7 Assume the same conditions as for Example Problem 6 except that your customer wants to use grade instead of grade. Solution: The clear span is the same (17'-0") as the design values for grade are the same as for grade. Roof Rafters Example Problem 8 Assume you are in an area having a snow load of 62.7 psf. What is the maximum span for a S-P-F grade 2x10 at 16" o/c? Solution: 1. Find the table containing the relevant information. Maximum Spans for Roof Rafters. 2. Review the notes to ensure that the table is based on the criteria that is appropriate. If you are viewing the correct table you will see that the deflection for this member is span/180. This is appropriate as no gypsum will be applied inside the attic. 3. Find the row dealing with S-P-F species, the row dealing with grade the row for 2x10. 4. Find the column dealing with roof snow load 62.7 psf the column for a joist spacing 16" o/c. 5. Read the span where the row column intersect i.e. 15'-11".
MAXIMUM SPANS FOR ROOF RAFTERS Maximum Span (ft.-in.) Roof Snow Load 20.9 psf (1.0 kpa) Roof Snow Load 41.8 psf (2.0 kpa) Roof Snow Load 62.7 psf (3.0 kpa) Roof Snow Load 83.5 psf (4.0 kpa) Species Rafter Rafter Spacing (in.) Rafter Spacing (in.) Rafter Spacing (in.) Rafter Spacing (in.) Grade Group Size 12 16 24 12 16 24 12 16 24 12 16 24 2x4 10-9 9-9 8-6 8-6 7-9 6-9 7-5 6-9 5-7 6-9 6-0 4-11 2x6 16-10 15-4 12-11 13-5 11-10 9-8 11-4 9-10 8-0 9-11 8-7 7-0 DFir-L 2x8 22-2 19-4 15-9 16-7 14-5 11-9 13-10 12-0 9-9 12-1 10-6 8-7 2x10 27-3 23-7 19-3 20-4 17-7 14-4 16-11 14-8 11-11 14-9 12-10 10-5 Hem-Fir S-P-F Northern Species Notes: 2x12 31-7 27-5 22-4 23-7 20-5 16-8 19-7 17-0 13-10 17-2 14-10 12-1 2x4 10-9 9-9 8-6 8-6 7-9 6-9 7-5 6-9 5-11 6-9 6-2 5-2 2x6 16-10 15-4 13-5 13-5 12-2 10-1 11-8 10-4 8-5 10-5 9-0 7-4 2x8 22-2 20-2 16-6 17-5 15-1 12-4 14-6 12-7 10-3 12-8 11-0 9-0 2x10 28-4 24-9 20-2 21-4 18-5 15-1 17-9 15-4 12-6 15-6 13-5 10-11 2x12 33-2 28-9 23-5 24-9 21-5 17-6 20-7 17-10 14-6 18-0 15-7 12-9 2x4 10-3 9-3 8-1 8-1 7-4 6-5 7-1 6-5 5-7 6-5 5-10 5-1 2x6 16-1 14-7 12-9 12-9 11-7 10-1 11-2 10-1 8-9 10-1 9-2 7-8 2x8 21-1 19-2 16-9 16-9 15-3 12-9 14-8 13-0 10-7 13-1 11-4 9-3 2x10 27-0 24-6 20-11 21-5 19-1 15-7 18-4 15-11 13-0 16-1 13-11 11-4 2x12 32-10 29-9 24-3 25-7 22-2 18-1 21-4 18-5 15-1 18-7 16-2 13-2 2x4 9-3 8-5 7-4 7-4 6-8 5-10 6-5 5-10 4-11 5-10 5-3 4-3 2x6 14-6 13-2 11-3 11-6 10-4 8-5 9-11 8-7 7-0 8-8 7-6 6-1 2x8 19-1 16-10 13-9 14-6 12-6 10-3 12-1 10-5 8-6 10-6 9-1 7-5 2x10 23-9 20-7 16-10 17-8 15-4 12-6 14-9 12-9 10-5 12-11 11-2 9-1 2x12 27-7 23-10 19-6 20-6 17-9 14-6 17-1 14-10 12-1 14-11 12-11 10-7 (a) Dead Load = 7 psf (b) Deflection = Span/180 Example Problem 9 In example Problem 8 you found the maximum span as being 15'-11". (a) If the slope of the roof was to be 4 in 12 what would the sloping length be? (b) If there was to be a 2' overhang, what length of lumber would you recommend to your customer? Solution (a): 1. Convert 15'-11" to feet. 11"= 11/12ths of a foot or 11/12 = 0.92'. Therefore 15'-11" = 15.92'. 2. From the Conversion Factors for Sloping Joists/Rafters table the 4:12 conversion factor is 1.054. 3. Hence the sloping length would be 15.92 x 1.054 = 16.78'. Solution (b): (Hint. First work with the horizontal lengths then convert to the sloping length.) 1. At one end there will be a need to cut off a small triangular piece of lumber so as to rest against the ridge beam at the top of the roof peak (see the figure dealing with sloping rafters). For ease of calculation assume this is 9" or 0.75' (9 / 12) which is just about the depth of the 2x10 joist. 2. On this basis the horizontal length will be the 9" from 1 above + span length + the bearing length on top of the outside wall (assume 3_" -or approximately 0.25' - for the width of the top wall plate) + overhang. Therefore the horizontal length is 0.75 + 15.92 + 0.25 + 2.00 = 18.92' 3. Calculate the rafter length as the horizontal length x the 4 in 12 conversion factor. 18.92'x 1.054 = 19.94'. Example Problem 10 Let s now go back to our 28' wide house where the clear span is 14'. Assume the roof slope is 1 in 6, there is a 2' overhang you are in a snow load region of 41.8 psf. What lumber size, o/c spacing overall length of rafter would you recommend to your customer? Solution: First let s determine the overall length of the rafter. This is done as the overall length could
influence the final decision. 1. As in Example Problem 9 the overall rafter length will be the triangle cut-off (as the slope is not excessively steep assume 0.75' as before) + clear span + bearing + overhang = 0.75 + 14.00 + 0.25 + 2.00 = 17.00'. 2. From the Conversion Factors for Rafters table the 6 in 12 conversion factor is 1.118. 3. Hence the sloping length would be 17.00 x 1.118 = 19.01'. As lumber is likely delivered to your store in 2 increments you will be recommending 20' length of lumber. Now let s determine the size spacing of the lumber to be used. Remember the clear span is 14'. 4. From the Maximum Spans for Roof Rafters table find the row dealing with S-P-F species, the row dealing with grade. 5. Find the column dealing with roof snow load 41.8 psf. 6. Where the row column intersect you find that: a 2x8 spans 16'-9" at 12" o/c, 15'-3' at 16" o/c 12'-9" at 24" o/c;, a 2x10 spans 21'- 5" at 12" o/c, 19'-1" at 16" o/c 15'-7" at 24" o/c. As you need a span of 14'-0" you can recommend either a 2x8 spaced at 16" o/c or a 2x10 spaced at 24" o/c. Due to the bearings overhang, the sloped rafter will need to be 20' long. Reducing Rafter Size Construction practices can reduce rafter size. How? Well, the maximum spans for rafters (as well as for the other tables in this chapter) are listed as horizontal clear spans. Therefore, any interior support that interrupts the overall span reduces the span. Example Problem 11 For example, in our 28' wide house, introduce a brace to reduce the 14'-0" span into two spans of 4'-8" 9'-4". We now have a maximum span of 9'-4". As in Example Problem 10, What size rafter do we now need? Solution: 1. From the Maximum Spans for Roof Rafters table find the row dealing with S-P-F species, the row dealing with grade. 2. Find the column dealing with roof snow load 41.8 psf. 3. Where the row column intersect you find that a 2x6 spans 10'-1" at 24" o/c. This exceeds the 9'-4" we require when using the bracing. So, you can recommend, providing the framing method uses the bracing, a 2x6 at 24" o/c rather than a 2x8 spaced at 16" o/c or a 2x10 spaced at 24" o/c. BUILT-UP FLOOR BEAMS You just learned how to select the proper size of floor joists that will hold up the finished floor, etc. Now we ll take a look at how to select a wood built-up beam or girder to hold up the floor joists. The beam that holds up the floor joists is usually a built-up wood beam made by nailing a number of pieces (usually 3) of dimension lumber (usually 2x10s) together. Another choice, though not too common except in post beam houses, is a solid wood beam of 4x8 up to 6x12. Steel beams are also common. They are usually designed by the steel supplier where the builder has identified the house width, the number storeys, space between posts or supports, etc. The supplier has a manual listing sizes needed to meet those conditions. A wood built-up beam, however, may have to be selected by the draftsperson or estimator at the building materials store. Many times the builder will tell you what size type wood girder they want all you have to do is to price it out /or see that the builder gets it. Once in a while you may be in a position to help somebody figure out what size wood girder is required.
If you can find your situation described in a reliable table it should be okay to suggest a size. However, as we ve said before: Never design a structural member. It is not worth the liability. And it s not the right thing to do anyway! Read the built-up beam sizes from the appropriate table, but never design them. A typical built-up floor beam table, for beams not supporting more than two floors, is shown below. Agencies publishing such tables usually provide a number of similar tables for supporting not more than one, two /or three floors. This chapter only provides the two floor case as the format of the table will be the same for all tables. In addition, beware that the tables do not allow for carrying of a roof (snow) load. In other words the building is framed using a truss system that carries the roof load to the outside walls the walls carry the load down through the walls to the foundation. The built up floor beam tables are not difficult to read. But make sure that you always use the appropriate table. And some agencies also provide tables that incorporate snow loads. Example Problem 12 Again use our 28' wide house. Assume we want to support two floors use DFir-L, grade for the built-up floor beam. What is the maximum span we can achieve with a 4-ply beam? Solution: 1. Find the table containing the information we require. ( Maximum Spans For Built-Up Floor Beams Supporting Not More Than Two Floors ). MAXIMUM SPANS FOR BUILT-UP FLOOR BEAMS SUPPORTING NOT MORE THAN TWO FLOORS Species Group DFir-L Hem-Fir S-P-F Northern Species Grade Notes: Maximum Span (ft.-in.) Size of Beam Supported Length 2x8 2x10 2x12 (ft.) 3-ply 4-ply 5-ply 3-ply 4-ply 5-ply 3-ply 4-ply 5-ply 8 7-5 8-6 9-6 9-0 10-5 11-8 10-6 12-1 13-6 10 6-7 7-8 8-6 8-1 9-4 10-5 9-4 10-10 12-1 12 6-0 7-0 7-9 7-4 8-6 9-6 8-7 9-11 11-1 14 5-7 6-5 7-2 6-10 7-11 8-10 7-11 9-2 10-3 16 5-3 6-0 6-9 6-5 7-4 8-3 7-5 8-7 9-7 18 4-11 5-8 6-4 6-0 6-11 7-9 7-0 8-1 9-0 20 4-8 5-5 6-0 5-9 6-7 7-4 6-8 7-8 8-7 8 7-9 8-11 10-0 9-6 10-11 12-3 11-0 12-8 14-2 10 6-11 8-0 8-11 8-6 9-9 10-11 9-10 11-4 12-8 12 6-4 7-4 8-2 7-9 8-11 10-0 8-11 10-4 11-7 14 5-10 6-9 7-7 7-0 8-3 9-3 7-11 9-7 10-9 16 5-3 6-4 7-1 6-4 7-9 8-8 7-2 8-11 10-0 18 4-10 6-0 6-8 5-9 7-2 8-2 6-7 8-1 9-5 20 4-6 5-7 6-4 5-4 6-7 7-9 6-1 7-6 8-11 8 8-0 9-3 10-4 9-10 11-4 12-8 11-5 13-2 14-8 10 7-2 8-3 9-3 8-9 10-2 11-4 10-2 11-9 13-2 12 6-7 7-7 8-5 8-0 9-3 10-4 9-4 10-9 12-0 14 6-1 7-0 7-10 7-5 8-7 9-7 8-7 9-11 11-1 16 5-8 6-7 7-4 6-10 8-0 8-11 7-9 9-4 10-5 18 5-3 6-2 6-11 6-3 7-7 8-5 7-1 8-9 9-10 20 4-10 5-10 6-7 5-9 7-2 8-0 6-7 8-1 9-4 8 6-5 7-5 8-4 7-10 9-1 10-2 9-2 10-7 11-9 10 5-9 6-8 7-5 7-0 8-2 9-1 8-2 9-5 10-7 12 5-3 6-1 6-9 6-5 7-5 8-4 7-5 8-7 9-8 14 4-10 5-7 6-3 5-11 6-10 7-8 6-11 8-0 8-11 16 4-7 5-3 5-11 5-7 6-5 7-2 6-6 7-5 8-4 18 4-3 4-11 5-6 5-3 6-1 6-9 6-1 7-0 7-10 20 4-1 4-8 5-3 5-0 5-9 6-5 5-9 6-8 7-5 (a) Spans apply only where the floors serve residential areas. (b) Spans are clear spans between supports. For total span (c) Provide a minimum of 3 1 / 2" of bearing at each support. (d) Supported length means one half the sum of the joists on both sides of the beam. (e) Straight line interpolation may be used for other supported lengths.
2. Review the notes to ensure that the table is based on the criteria that is appropriate. You will note that supported length is defined as the one half the sum of the joists on both sides of the beam. We are using our 28' wide house that has floor joists having a clear span of 14'. So, one-half of 14' is 7'. However, the beam supports the ends of two floor joists, so 7' +7' = 14'. Therefore, the supported length we are interested in is 14'. The figure below provides a visual dealing with supported length. 3. Find the row dealing with DFir-L, the row dealing with grade the row for 14' supported length. 4. Find the columns dealing with 4-ply beams. 5. Read the spans where the row columns intersect. i.e. 6'-5" for 4-2x8s, 7'-11" for 4-2x10s 9'-2" for 4-2x12s. Therefore, the longest span is 9'-2" for a 4-ply 2x12 built-up beam. Example Problem 12 Let s return to using the grade S-P-F. Our customer with the 28' wide house tells us the house is 50' long that he/she wants a minimum number of posts in the basement supporting the built-up beam carrying two floors. What can you advise? Solution: In addition, in looking up the span information requested by your customer, you likely noticed that a 4-ply 2x12 built-up beam had a clear span of 9'-11". As the house is 50' long each beam requires 3 1 / 2" bearing at each end, you can advise your customer that by spacing the columns at 10' apart (i.e. five spaces at 10' = 50') the built up beam could be sized at 4-ply 2x12. Your familiarity with the tables extending the question asked has allowed you to provide your customer with some options. Congratulations! HEADERS / LINTELS Openings in walls are necessary for doors, windows other elements. When an opening is put in a wall, it cuts off some supports carrying loads down to the foundation from there to the footings ultimately the soil. The supporting members cut off are generally the wall studs though it could be posts in a post beam type house. The loads that were being carried by these cut off members have to be transferred to other load carrying members nearby. Headers, or frequently referred to as lintels, are the terms given to supporting members that transfer these loads. The header/lintel size depends on many things just as the size of joists, rafters built-up beams did, including how much weight they have to carry. However, this depends on the house width, height, location of header, etc. The header size also depends on the strength of the wood, the size of the wood the number of pieces being used to make the header. HEADERS / LINTELS 1. You know the supported length is 14'. So, find the row dealing with S-P-F, the row dealing with grade the row for 14' supported length. 2. Look at the spans across this row, where you can identify that a 5-ply 2x12 built-up beam provides the maximum span of 11'-1".
Again, several agencies publish header/lintel tables. Once again, then, if you know how to read these tables accurately you can make sure your customers are using properly designed headers/lintels that are large enough to carry the loads safely, but not oversized to increase the material costs. We ll be demonstrating practicing reading one of these tables shortly. When the header has to carry a load it must be accurately designed. However, there are quite a number of headers that don t carry any significant load at all. Normally these headers can be a single 2x4 turned flat. Used just to "frame out" the opening. A window placed on the gable end of a one story house, for example, has no significant load over it as the roof loads are transferred to the side walls rather than the end (gable) wall. The main purpose of the studs in that case is to provide nailing backing for exterior sheathing siding for interior wall finish. So when the studs are cut off to make the window rough opening, no load carrying header is required. All the interior walls on the top floor of a trussed roof building are normally non-load bearing (the truss carries all the loads to the outside walls). So when the studs are cut off to make the rough openings for interior doors, there is no weight that has to be transferred anywhere. Again then, 2x4s turned flat can be used to frame out the opening. Even with a conventionally framed roof, only bearing wall(s) need a load bearing header. All the rest of the partitions are non-load bearing. So study your specific house, then apply what you are learning you can design proper header sizes for many homes. Now, before we do some Header/Lintel Example Problems let s look at the table (on the next page) Maximum Spans for 2-Ply Headers/Lintels with Non-Structural Sheathing Supporting One Storey Roof Snow Loads. The title identifies that the table is for headers/lintels with non-structural sheathing. This means that the sheathing, or the manner it is fastened to the building frame is such that it does not help to carry the load around the wall opening. In some cases when structural sheathing is used, lintel spans may be increased as the sheathing helps spread the load out over a larger area. In fact, if you examine the notes of the table you will of see exactly that. Note (e) identifies a 15% increase in spans when structural panels of a minimum thickness, conforming to a specific stard fastened in a specified way are used. A further review of the notes also identifies that under certain conditions (floor joists spanning the full width of the building without support) spans are to be reduced by 15%. The notes to this table reinforce the importance of reviewing understing all the information: title, column row headings, notes, etc., on any table that you are going to use to provide information to a customer. A final comment before moving to a couple of examples. The header/lintel table in this chapter is only one way in which information can be presented. Other agencies may provide separate tables for most cases encountered in regular construction. They may also rely on notes to cover off construction details not listed in the table they have chosen to publish. A good first step in getting the tables you want, is to discuss the need for tables with your local building official. Now an example problem. Example Problem 14 Assume a 32 foot wide house where you are using insulation sheathing board you have a 10' rough opening on the wall carrying the roof load one storey. You are in a snow load area of 41.8 psf. What is the smallest Hem-Fir, grade, 2-ply header you can use? (You have already located the table are familiar with the notes.) Solution: 1. Find the row dealing with Hem-Fir, grade the row of supported length of 10'. 2. Find the column dealing with the snow load of 41.8 psf. 3. Read the spans where the row column intersect (5'-1", 6'-3", 7'-7" 8'-10"). So, the table you have doesn t provide a solution.
And you will have to locate another table, refer your customer to an engineer, or provide some other solutions. Here are some suggestions. You could tell your customer that the window size could be reduced to under the 8'-10" or, what about changing the type of sheathing? The notes to the table allow for an increase in span of 15% providing specified sheathing is used. For the 2-ply 2x12 the maximum span is 8'-10". 8'-10" = 8' + 10/12' = 8' + 0.83' = 8.83'. Now increase this by 15 %. 15% = 1.15. 8.83 x 1.15 = 10.15', which is greater than the 10' required by your customer. Now, you have three suggestions for your customer. 1. Reduce the opening to less that 8' -10". 2. Refer the solution to a design engineer. 3. Use a 2-ply 2x12 lintel along with approved structural sheathing appropriate nailing. All this with only the information contained in the table of this chapter. If you have followed up by obtaining a complete set of available tables from agencies providing them you likely will have a number of solutions using the material you are regularly stocking in your store. MAXIMUM SPANS FOR 2-PLY HEADERS/LINTELS WITH NON-STRUCTURAL SHEATHING SUPPORTING ONE STOREY AND ROOF SNOW LOADS Species Group DFir-L Hem-Fir S-P-F Northern Species Notes: Grade Maximum Span (ft.-in.) Supported Snow Load 20.9 psf (1.0 kpa) Snow Load 41.8 psf (2.0 kpa) Snow Load 62.7 psf (3.0 kpa) Length Beam Size of 2-ply at Beam Size of 2-ply at Beam Size of 2-ply at (ft.) 2x6 2x8 2x10 2x12 2x6 2x8 2x10 2x12 2x6 2x8 2x10 2x12 8 6-5 7-9 9-6 11-0 5-5 6-7 8-1 9-5 4-10 5-10 7-2 8-4 10 5-9 6-11 8-6 9-10 4-10 5-11 7-3 8-5 4-4 5-3 6-5 7-5 12 5-3 6-4 7-9 9-0 4-5 5-5 6-7 7-8 3-11 4-9 5-10 6-10 14 4-10 5-11 7-2 8-4 4-1 5-0 6-1 7-1 3-8 4-5 5-5 6-4 16 4-6 5-6 6-9 7-10 3-10 4-8 5-9 6-8 3-5 4-2 5-1 5-11 18 4-3 5-2 6-4 7-4 3-8 4-5 5-5 6-3 3-3 3-11 4-9 5-7 20 4-1 4-11 6-0 7-0 3-5 4-2 5-1 5-11 3-1 3-9 4-6 5-3 8 6-8 8-2 10-0 11-7 5-9 6-11 8-6 9-10 5-1 6-2 7-6 8-9 10 6-0 7-4 8-11 10-4 5-1 6-3 7-7 8-10 4-6 5-6 6-9 7-9 12 5-6 6-8 8-2 9-5 4-8 5-8 6-11 8-1 4-2 5-0 6-0 6-9 14 5-1 6-2 7-6 8-9 4-4 5-3 6-5 7-3 3-10 4-6 5-4 6-1 16 4-9 5-9 7-1 8-2 4-0 4-10 5-9 6-7 3-5 4-1 4-10 5-7 18 4-6 5-5 6-8 7-8 3-9 4-5 5-4 6-1 3-2 3-9 4-6 5-2 20 4-3 5-2 6-3 7-1 3-6 4-1 4-11 5-8 2-11 3-6 4-2 4-10 8 6-10 8-5 10-4 12-0 5-11 7-2 8-10 10-3 5-3 6-4 7-10 9-1 10 6-2 7-7 9-3 10-9 5-3 6-5 7-10 9-2 4-8 5-8 7-0 8-1 12 5-8 6-11 8-5 9-9 4-10 5-11 7-2 8-4 4-3 5-2 6-4 7-4 14 5-3 6-5 7-10 9-1 4-6 5-5 6-8 7-9 4-0 4-10 5-9 6-7 16 4-11 6-0 7-4 8-6 4-2 5-1 6-3 7-1 3-8 4-4 5-3 6-0 18 4-8 5-8 6-11 8-0 3-11 4-9 5-9 6-6 3-5 4-0 4-10 5-6 20 4-5 5-4 6-6 7-7 3-9 4-5 5-4 6-1 3-2 3-9 4-6 5-2 8 5-7 6-9 8-3 9-7 4-9 5-9 7-1 8-2 4-2 5-1 6-3 7-3 10 5-0 6-1 7-5 8-7 4-3 5-2 6-4 7-4 3-9 4-7 5-7 6-6 12 4-7 5-6 6-9 7-10 3-11 4-9 5-9 6-8 3-5 4-2 5-1 5-11 14 4-3 5-1 6-3 7-3 3-7 4-4 5-4 6-2 3-2 3-10 4-9 5-6 16 3-11 4-10 5-10 6-10 3-4 4-1 5-0 5-10 3-0 3-7 4-5 5-2 18 3-9 4-6 5-6 6-5 3-2 3-10 4-8 5-6 2-10 3-5 4-2 4-10 20 3-6 4-3 5-3 6-1 3-0 3-8 4-6 5-2 2-8 3-3 3-11 4-7 (a) Supported length means half the span of the longest supported member. (b) If floor joists span the full width of the building without support, spans shall be reduced by 15%. (c) For ends of lintels fully supported by wall, provide a minimum 1 1 / 2" of bearing for spans up to 10'; or 3" of bearing for lintel spans greater than 10'. (d) A single piece of 3 1 / 2" thick lumber (of the same species grade) may be used in lieu of 2 pieces of 1 1 / 2" lumber on edge. (e) When structural sheathing is used, lintel spans may be increased by 15%. Structural sheathing consists of a minimum 3 / 8" thick structural panel conforming to CSA O121, CSA O151, CSA O437 or CSA O325 fastened with at least two rows of fasteners to the exterior face of the lintel a single row to the top plates studs.
OTHER KINDS OF FRAMING MEMBERS Manufactured lumber alternate types of framing members are becoming more popular. There are studs made of a combination of particle board lumber. Of course steel studs, joists, etc., are available. Joists beams can be made from laminated wood, combinations of plywood, lumber /or laminated materials. Each of these engineered products has span strength information available. Get use information that is specific to the product your store stocks. It would be impractical to cover all these patented products in a course such as this. But the concepts covered in this chapter, if understood, will help you decide when how to use new products, as they come along. Some of these products may be superior to the stard wood products are catching on so don t be afraid to consider using them when if appropriate. TRUSS ROOF SYSTEMS A special caution. Truss roof systems are designed entirely differently. The previous information on finding rafters cannot be used to find truss sizes. The concept of a truss is much different as far as member sizes are concerned. The span, slope, dead live loads, etc., are given to the truss manufacturer they have engineered trusses available to meet your requirements. Contact the truss manufacturer in your area for their information literature. RECAP You should now be able to figure out sizes of floor joists, ceiling joists, rafters headers / lintels, etc. Many people are guessing or going by tradition to find sizes. In many cases this has been working out fine, still, if you can figure these member sizes using a solid basis such as the building code approved in your area, it should give you confidence could be a big help to the customers contractors you work with. The main point of this chapter was to familiarize you with reading span tables. Your building code official will be able to suggest the tables loads in effect in your area. Don t hesitate to contact this official. Once you have obtained the tables approved for use in your jurisdiction, why not challenge one or more of your colleagues by taking turns asking each other questions that require use of the span table to find answers. All of you can then become familiar with using the span table which will be beneficial when a customer asks for your advice.
LUMBER ORDERING INFORMATION This page gives approximate lumber quantities contained in truckload railcar lumber shipments. Of course regional customs vary. That s why there is room for you to fill in information specific to your store. When ordering lumber it is helpful to know what quantities make up stard units. It is usually advantageous to order full units. The price is better, bed units are easier to load unload (with the right equipment) delivery is usually faster to you because of easier hling. The main reason for changing quantities with size is to try to keep all the units approximately the same size to simplify warehousing. The table below shows the most common unit quantities listed first in each size SIZE PIECES PER UNIT NUMBER OF PIECES (wide x high) APPROX. UNIT DIMENSIONS (inches) 2x4 208 13 x 16 45 x 25 2x4 192 12 x 16 42 x 25 2x4 180 12 x 15 42 x 23 2x4 2x4 Studs 300 2x4 Studs 208 13 x 16 45 x 25 2x4 Studs 192 12 x 16 42 x 25 2x4 Studs 2x6 Studs 128 8 x 16 44 x 25 2x6 Studs 120 8 x 15 44 x 23 2x6 Studs 2x6 128 8 x 16 44 x 25 2x6 120 8 x 15 44 x 23 2x6 2x8 96 6 x 16 43 1 / 2 x 25 2x8 90 6 x 15 43 1 / 2 x 23 2x8 2x10 80 5 x 16 46 x 25 2x10 75 5 x 15 46 x 23 2x10 2x12 64 4 x 16 45 x 25 2x12 60 4 x 15 45 x 23 2x12 category, next are unit quantities used by some lumber mills /or wholesalers which may or may not be available in your area. There is also an empty line for you to fill in the quantities commonly available to you, if different than any of those listed. TRUCKLOADS Common truckload quantities are from 23,000 Board feet (Bd.Ft.) to 30,000 Bd. ft. RAILCAR LOADS A boxcar might be from 40,000 to 50,000 Bd. ft. A flat car from 70,000 to 100,000 Bd. ft. A good portion of your lumber cost can be the freight charges from the mill to your store. Freight charges are sometimes a determining factor in the kind of lumber you stock. Certain minimum weight amounts give you the best freight rate. Check with the railroad, lumber mill or broker. You are given a certain amount of time, such as 48 hours, to unload a car after the railroad has notified you the car is in position to be unloaded. You are charged demurrage if you take too long to unload a railcar. If you order lumber in unit quantities (called bunks, skids, etc.) it s bed together is easy fast to unload by forklift. If your lumber is delivered in a boxcar loose, such as boards might be, it can be a major project to get it unloaded in the allotted time. Much lumber is delivered by truck, of course is usually easy to unload. LUMBER LENGTHS Lumber is generally available in lengths of 8' to 16' in 2' increments. Longer lengths to 26' may be available in the coastal species. And even longer lengths may be available from a few mills, though there is usually a price premium after lengths of 16' or 18'.
BOARD FEET Most lumber today is sold by the piece. It was common to sell lumber by the board foot in the old days. Some transactions still take place by the board foot. So it s still a good idea to learn about board feet. A board foot is 144 cubic inches of lumber. It s often pictured as a piece of lumber 12" square 1" thick, though it can be a 2"x6" 1 foot long (12"), or any combination that equals 144 cubic inches. These next two pages contain a table on board feet, plus board foot formulas, examples practice problems to reinforce your board foot knowledge. To use the Board Feet Per Piece Table Nom. Size column to find the lumber size, then read across to the correct column. The numbers have always been rounded up. The two most frequent numbers are 0.333, which goes on forever, this is rounded to 0.34 or 0.3334; 0.666, which is rounded to 0.67 or 0.6667. Lineal Feet per Board Foot Board Feet per Lineal Foot Length BOARD FOOT PER PIECE 8 Ft 10 Ft 12 Ft 14 Ft 16 Ft 18 Ft 20 Ft 22 Ft 24 Ft 26 Ft Nom. Size 6.00 0.1667 1x2 1.34 1.67 2.00 2.34 2.67 3.00 3.34 3.67 4.00 4.34 4.00 0.2500 1x3 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 3.00 0.3334 1x4 2x2 2.67 3.34 4.00 4.67 5.34 6.00 6.67 7.34 8.00 8.67 2.00 0.5000 1x6 2x3 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 1.50 0.6667 1x8 2x4 5.34 6.67 8.00 9.34 10.67 12.00 13.34 14.67 16.00 17.34 1.20 0.8334 1x10 6.67 8.34 10.00 11.67 13.34 15.00 16.67 18.34 20.00 21.67 1.00 1.0000 1x12 2x6 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 0.75 1.3340 2x8 4x4 10.67 13.34 16.00 18.67 21.34 24.00 26.67 29.34 32.00 34.67 0.60 1.6667 2x10 13.34 16.67 20.00 23.34 26.67 30.00 33.34 36.67 40.00 43.34 0.50 2.0000 2x12 4x6 16.00 20.00 24.00 28.00 32.00 36.00 40.00 44.00 48.00 52.00 0.34 3.0000 6x6 24.00 30.00 36.00 42.00 48.00 54.00 60.00 66.00 72.00 78.00 READING THE BOARD FOOT TABLE EXAMPLES You can find out how many lineal feet (LFT) are in a certain number of board feet of a certain size piece of lumber by using the left column. Example: To find how many LFT of 2x4 in 300 Bd. Ft. of 2x4, look up the LFT in one Bd. Ft. of 2x4. It shows 1.50. Multiply 1.50 x 300 you find 450 LFT of 2x4 in 300 Bd. Ft. To find how many board feet in a certain amount of lineal footage, multiply the board feet per lineal foot (found in the second column from the left) of the given size times the lineal footage. Example: The reverse of the example above. How many Bd. Ft. in 450 LFT of 2x4? There is 0.6667 Bd. Ft per LFT in a 2x4 (from table above), 0.6667 x 450 = 300 Bd. Ft in 450 LFT of 2x4. To find board feet per piece, look down the "Nom. Size" column for the size you want, then read to the right, under the length. That number is the Bd. Ft. per piece. Example: A 22' long 2x12 = 44 Bd. Ft.
BOARD FEET (cont.) FORMULA FOR FINDING BOARD FEET [NUMBER OF PIECES x THICKNESS (in) x WIDTH (in) x LENGTH per piece (ft)] / 12 = BOARD FEET or [LINEAL FEET (ft) x THICKNESS (in) x WIDTH (in)] / 12 = BOARD FEET Example: Find how many board feet in 20 Pcs. of 2x6-16'. Answer: 320 Bd. Ft. Solution: 20 x 2 x 6 x 16 = 3840. Divided by 12 = 320 Example: Find how many board feet in 500 LFT of 2x10. Answer 833.34 Bd. Ft. Solution: 500 x 2 x 10 = 10,000. Divided by 12 = 833-1/3 CHANGING BOARD FEET TO LINEAL FEET Lineal feet is like placing the lumber end to end just counting the total length (sometimes called running feet). For example, 10 pieces of 2x4-10' would be 100 Lineal feet (LFT). Sometimes you may have to change board feet into LFT. Here s how: 1. Find how many board feet are in one LFT of the given size (you could calculate it with the board foot formula, or look in the Board Feet per Piece Figure. 2. Divide that number into the board feet given. Example: How many LFT of 1x3 lumber in 1000 board feet? Answer: 4000 LFT Solution: 1 pc. of 1x3-1' long contains 0.25 Bd. Ft.; 1000 Bd. Ft. divided by 0.25 = 4000 CHANGING BOARD FEET TO NUMBER OF PIECES A list of materials may have been priced out by the thous board feet. Now the customer wants the material delivered. The bid may show 2000 Bd. Ft. of 2x8 at a certain price. The customer wants you to deliver that much, but in 14' lengths. Example: How many 2x8s - 14' should be delivered? Answer: 107 or 108 Solution: 1. Find out how many Bd. Ft. in one piece of the desired size. 2. Divide that number into the allotted amount. 3. Round up or down depending on situation. 1 pc 2x8-14' = 18.667 Bd. Ft.; 2000 + 18.667 = 107.14 pcs.
BOARD FEET (cont.) PRICING LUMBER BY THE THOUSAND BOARD FEET Lumber is often priced by the thous board feet. It s often written like this example. $600 per M (M being the Roman Numeral for 1,000.) Or $600/M; or $600/MBF ($600 per 1,000 Board Feet) more. To price lumber per M, multiply the price per M x the number of board feet, then divide by 1,000 (to divide by 1,000 simply move the decimal point three places to the left). A couple of alternate methods are to divide the board feet by 1,000 then multiply by the per M price, or divide the price by 1,000 then multiply by the board feet. It all works out the same. Example: How much does 350 Bd. Ft. of 2 x 10 cost if the price is $500/M? Answer: $175 Solution: 350 x $500 = 175,000 Dividing by 1,000 (moving the decimal 3 places to the left) = $175.00 Sometimes you have to calculate the board feet first, but you know how to do that! PRACTICE PROBLEMS Do these problems like the examples on this page. Then check them by doing them again using the table in Figure 2-22. Then check with answers given at end of page. Find board feet for problems 1-6 1. 15 PCS 2 x 6-10' = 2. 3 PCS 2 x 10-16' = 3. 1000 LFT 2 x 8 = 4. 7 PCS 1 x 4-4' = 5. 560 LFT 2 x 4 = 6. 25 PCS 2 x 4-15' (Special order) = Find lineal feet for problems 7-10 7. 300 Bd. Ft. of 2 x 4 = LFT 8. 1500 Bd. Ft. of 1 x8 = LFT 9. 210 Bd. Ft. of 2 x 4 = LFT 10. 800 Bd. Ft. of 2 x 10 = LFT Find number of pieces for problems 11-14 11. 500 Bd. Ft. of 1 x 3-10' = PCS 12. 1100 Bd. Ft. of 2 x 4-16' = PCS 13. 200 Bd. Ft. of 1 x 2-14' = PCS 14. 3000 Bd. Ft. of 4 x 4-8' = PCS Price out problems 15-20, all at $550/M 15. 10 PCS 2 x 10-16' = $ 16. 20 PCS 2 x 4-8' = $ 17. 9 PCS 1 x 4-16' = $ 18.300 PCS 2 x 4-16' = $ 19.1000 Bd. Ft. 2 x 8 = $ 20.1000 LFT 2 x 8 = $ Answers: Use your judgement. If you re within one Bd. Ft., or $1.00 you re probably close enough. 1. 150 6. 250 11. 200 16. 107 BF/ $58.85 2. 80 7. 450 12. 103+ 17. 48 BF/ $26.40 3. 1333.33 8. 2250 13. 85+ 18. 3200 BF/ $1760.00 4. 9.33 9. 315 14. 281+ 19. $550.00 5. 373.33 10. 480 15. 267 BF/ $146.85 20. 1334 BF/ $733.70
LUMBER COVERAGE TABLES Since lumber is sold board feet is figured on the nominal size of lumber, some people are misled as to how much area lumber will cover. The problem is that a 1x8, for example, is actually 7_" wide, not a full 8". All lumber has this same problem. If you have the right tables available you can easily tell how much to add to make up for the difference in nominal actual lumber sizes. The amount to add to make up for the difference in actual nominal size can be calculated exactly. When using the products, however, some waste usually occurs. Pieces are cut off are too short to be used, there could be some bad spots, etc. The amount of waste depends on the builder. Our tables will show the amount extra needed because of the difference in nominal actual size a column that includes 5% more for waste. Some builders may require 10% waste, or more. If so, you can adapt these tables quite easily. There is also a column in cases of diagonal installation, where an additional 6 percentage points has been added to the normal multipliers because of the extra waste associated with diagonal installation. Lumber Type S4S Boards Shiplap Tongue & Groove Bevel siding 1 lap Drop siding ESTIMATING LUMBER COVERAGE Board Feet Board Feet required per required per Nominal SqFt of surface Actual Width SqFt of Size Overall Face surface 5 % waste Diagonal (in) (in) No waste 1x4 3 1 / 2 3 1 / 2 1.14 1.19 1x6 5 1 / 2 5 1 / 2 1.09 1.14 1x8 7 1 / 4 7 1 / 4 1.10 1.15 1.21 1x10 9 1 / 4 9 1 / 4 1.08 1.13 1x12 11 1 / 4 11 1 / 4 1.07 1.12 1x8 7 1 / 4 6 7 / 8 1.16 1.21 1.27 1x10 9 1 / 4 8 7 / 8 1.13 1.18 1.24 1x4 3 3 / 8 3 1 / 8 1.28 1.33 1x6 5 3 / 8 5 1 / 8 1.17 1.22 1x8 7 1 / 8 6 7 / 8 1.16 1.21 1/2x4 3 1 / 2 3 1 / 2 1.60 1.65 1/2x6 5 1 / 2 5 1 / 2 1.33 1.38 1/2x8 7 1 / 4 7 1 / 4 1.28 1.33 5/8x10 9 1 / 4 9 1 / 4 1.21 1.26 1x6 5 3 / 8 5 1 / 8 1.17 1.22 1x8 7 1 / 8 6 7 / 8 1.16 1.21 READING COVERAGE TABLES Select the kind of lumber used. Multiply the square feet of area (length x width) to be covered times the multiplier from one of the last two columns, depending on whether you want to include waste. Example: How many Bd. Ft. are required to cover a floor 15' by 20' if you are using 1x8 S4S boards want a 5% waste factor? Answer: 345 Bd. Ft. Solution: 15x20 = 300 Sq. Ft. times 1.15 (multiplier across from 1x8 S4S Boards, in 5% waste column). Example: How much 1 / 2x8 bevel siding to cover 800 Sq. Ft. of wall? (include waste) Answer: 1064 Bd. Ft. Solution: Locate multiplier of 1.33 across from 1 / 2x8 Bevel siding. Multiply 1.33 x 800 = 1064. ( 1 / 2" in lumber is still figured as 1" for finding board feet).
CONVERSION FACTORS FOR SLOPING JOISTS/RAFTERS Slope (in 12) Conversion Factor For Common Joist/Rafter For Hip/Valley Joist/Rafter 3 1.031 1.436 4 1.054 1.453 5 1.083 1.474 6 1.118 1.500 7 1.158 1.530 8 1.202 1.563 9 1.250 1.601 10 1.302 1.641 11 1.357 1.685 12 1.414 1.732 13 1.474 1.781 14 1.537 1.833 15 1.601 1.887 16 1.667 1.944 READING SLOPING JOISTS/RAFTERS LENGTH TABLES First find the common rafter (or joist) run including the overhang. The common rafter run is the horizontal, or flat distance the rafter covers. For example, if your house is 26' wide has a 2' overhang the common rafter run is 15'. Here s why. 1/2 the house width of 26' is 13' (the rafters peak in the middle of the house), then add the 2' overhang for a total rafter run of 15'. Next find out what the roof slope is to be. Assume it s 4:12 (4 in 12). Then go to the Conversion Factor table, read across from 4:12 to "common rafter" column. It is 1.054. Multiply that times 15 to find the actual rafter length to be 15.81'. That means you ll be using 16' stock. To find the length of a hip or a valley rafter for this same roof, multiply the common rafter run (15') times the number in the far right column, which is 1.453 to get a hip or valley rafter length of 21.8', or use 22' stock. Now try doing the calculations for buildings 22' 28' 32' wide. All with a 5:12 rise to run a 2' overhang see if you get the answers shown below. Answers: 22' bldg = 22 / 2 =11, +2' overhang = 13 x 1.083 = 14.08' 28' bldg = 17.33' 32' bldg = 19.49'
CANADIAN IMPERIAL AND METRIC MEASUREMENTS Canadians generally use a mixture of measurement units. Liquid volumes are typically based on the metric (SI) system. Temperatures distances are commonly specified using metric terminology. Weights, depending on the type of product, use either the metric or Canadian Imperial system. Lengths dimensions of construction products, particularly for residential use, are generally in Canadian Imperial measurements. Canadian building codes are written using metric units. But the construction trades, particularly those in residential construction, typically use the Canadian Imperial system. This mixture of measurement systems frequently results in many product manufacturers providing information using both systems. Unfortunately, the approaches used in presenting the converted measurements are not consistent. Some information is based on exact conversion measurements whereas other information is based on rounded measurements. From your perspective in communicating with your customer it is important to recognize that in some instances the exact conversion is necessary in other instances a more rounded conversion is appropriate. CONVERSION FACTORS 1 inch (in.) = 25.4 mm 1 ounce - avoirdupois (oz.) = 28.35 g 1 foot (ft.) = 0.3048 m 1 pound - avoirdupois (lb.) = 0.454 kg 1 yard (yd.) = 0.9144 m 1 pound per square inch (psi) = 6.895 kn/m 2 1 fluid ounce - US (oz.) = 0.0296 L 1 pound per square foot (psf) = 0.04788 kpa 1 fluid ounce - Canadian (oz.) = 0.0284 L 1 gallon - US (gal.) = 3.785 L 1 gallon - Canadian (gal.) = 4.546 L Celsius temperature = (Fahrenheit temperature - 32) / 1.8 SOME TYPICAL MEASUREMENTS FOR LUMBER PRODUCTS ( rounded conversions) Length Length in. mm ft. m 1 1 / 2 38 8 2.44 2 1 / 2 64 10 3.05 3 1 / 2 89 12 3.66 4 1 / 2 114 14 4.27 5 1 / 2 140 16 4.88 6 1 / 2 165 18 5.49 7 1 / 4 184 20 6.10 9 1 / 4 235 22 6.71 11 1 / 4 286 24 7.32 13 1 / 4 337 26 7.92 15 1 / 4 387 26 Note: Always consult your provincial local codes B2 LUMBER: USE IN CONSTRUCTION
LUMBER PRODUCTS IN YOUR STORE In Your Store is a worksheet where you apply the knowledge you have learned in this chapter to the products you stock in your store. You may be able to find the answers on your own, or you may want to ask some of the people you work with for help. There are no test questions on this information, as the answers vary with location local custom. Do not send these answers in for correcting. This is a worksheet to help you get more familiar with your store. It becomes a reference tool for you to review when you need a refresher about what your store stocks. DIRECTIONS: Take your copy of this page from your test package. Fill out the blanks as appropriate for your situation. Sometimes more or less information could be entered. The object of the exercise is not to fill in blanks, but to learn more about the products covered in this chapter, as applied to the store you work in. So just use this exercise as a guide. What transportation lines serve your store? Rail Truck List the species grade of lumber stocked? 2x4 Studs 2x4s 2x6s 2x8s 2xl0s 2x12s List the quantity contained in your units of lumber. 2x4 Studs 2x4s 2x6s 2x8s 2xl0s 2x12s Name of some Lumber brokers/wholesalers/mills your store buys from: List the Manufactured framing members stocked or available? (such as TJI s, laminated garage door headers, etc.) What is your governing building code, if any? Who is your building code official? Location? What is the Live load required for roofs? Any other special requirements? NOTES: