PRESENTATION OUTLINE MUBEC & IRC APPLICABILITY & ADMIN. 6/17/2015 RESIDENTIAL STRUCTURAL SYSTEMS. Carmen B. Bombeke, P.E.

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1 MUBEC & IRC APPLICABILITY & ADMINISTRATION RESIDENTIAL STRUCTURAL SYSTEMS Carmen B. Bombeke, P.E. IRC FLOORS QUESTIONS & ANSWERS PRESENTATION OUTLINE Maine Uniform Building & Energy Code (MUBEC) IRC 2009 Structural Chapters all apply with limited to no revisions by adoption. Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Scope and Administration Definitions Building Planning Foundations Floors Wall Construction Wall Covering Roof Ceiling Construction Roof Assemblies Chimneys and Fireplaces R101.2 Scope. Applies to: Construction Alteration Movement Enlargement Replacement Repair Equipment Use and Occupancy Location Removal Demolition OF Detached One and Two Family Dwellings Townhouses Not more than 3 stories above grade Separate Means of Egress Accessory Structures MUBEC & IRC APPLICABILITY & ADMIN. MUBEC & IRC APPLICABILITY & ADMIN. 1

2 R106.1 Submittal documents. Construction documents and other data Prepared by a registered design professional where required by the statues of the jurisdiction. Where special conditions exist, the building official is authorized to require additional construction documents to be prepared by a registered design professional. R Information on construction documents. Construction documents shall: Be drawn on suitable material Clearly show location, nature and extent of work proposed Show in detail that work will conform to the provisions of this code and relevant laws, ordinances, rules and regulations Per definition, shall be drawn to an appropriate scale MUBEC & IRC APPLICABILITY & ADMIN. MUBEC & IRC APPLICABILITY & ADMIN. Section R202 DEFINITIONS BUILDING OFFICIAL. The officer or the designated authority charged with the administration and enforcement of this code. APPROVED. Accepted by the building official. REGISTERED DESIGN PROFESSIONAL. An individual who is registered or licensed to practice their respective design profession LIGHT FRAME CONSTRUCTION. A type of construction whose vertical and horizontal structural elements are primarily formed by a system of repetitive wood or cold formed steel framing members. MUBEC & IRC APPLICABILITY & ADMIN. Section R301 DESIGN CRITERIA R Construction systems. The requirements of this code are based on platform and balloon framed construction for light frame buildings. The requirements for concrete and masonry buildings are based on balloon framing system. Other framing systems must have equivalent detailing to ensure force transfer, continuity and compatible deformations. R Engineered design. When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. 2

3 Section R301 DESIGN CRITERIA R301.2 Climatic and geographic design criteria. Buildings shall be constructed in accordance with the provisions of this code as limited by the provisions of this section. Additional criteria shall be established by the local jurisdiction and set forth in Table R301.2(1). TABLE R301.2(1) CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA WIND DESIGN SEISMIC SUBJECT TO DAMAGE FROM WINTER ICE BARRIER MEAN GROUND SNOW LOAD Speedd (mph) Topographic DESIGN Frost line effects k CATEGORY f Weatheringa depth b Termitec DESIGN TEMP e UNDERLAYMENT REQUIRED h FLOOD AIR FREEZING HAZARDS g INDEX i ANNUAL TEMP j See Handout Online Image Sources: content/bcgbc4010a/02_force_systems/topic_index.htm Section R301 DESIGN CRITERIA R Wind limitations. R Design Criteria. In regions where basic wind speeds equal or exceed 100 mph in hurricane prone regions the design of buildings shall be in accordance with one of the following methods: 1. AF&PA Wood Frame Construction Manual for One and Two Family Dwellings (WFCM) 2. ICC 600 Standard for Residential Construction in High Wind Regions 3. ASCE 7 Minimum Design Loads for Buildings and Other Structures 4. AISI S230 Standard for Cold Formed Steel Framing Prescriptive Method for one and Two Family Dwellings 5. Concrete construction still per IRC 6. SIP walls still per IRC V >= 100 mph 3

4 Section R301 DESIGN CRITERIA R Seismic provisions. The seismic provisions of this code shall apply to buildings constructed in Seismic Design Categories C, D 0, D 1 and D 2, as determined in accordance with this section. Exception. Detached one and two family dwellings located in Seismic Design Category C are exempt from the seismic requirements of this code. Section R301 DESIGN CRITERIA R Snow loads. Buildings in regions with ground snow loads greater than 70 psf shall be designed in accordance with accepted engineering practice. Ground snow load > 70 psf Seismic Design Category C MUBEC & IRC APPLICABILITY & ADMINISTRATION IRC FLOORS Three Primary Roof Framing Concepts Discussed Today: Pre engineered roof trusses Structural ridge construction Rafters with ceiling joists or rafter ties QUESTIONS & ANSWERS PRESENTATION OUTLINE 4

5 Online Image Sources: Pre-engineered roof trusses: Benefits: Cost effective, rapid installation, engineered for gravity loads, spread loads to exterior walls (not always), resist thrust internally, limited posting req d Drawbacks: Geometric requirements, delivery site constraints, lead time Online Image Sources: Online Image Sources: beams and ridge boards modern structural solutions for a frames/ Pre engineered trusses make approval easier Structural ridge beam construction: Benefits: Accommodates cathedral ceilings, dormers, roof openings, etc., eliminates outward thrust at walls Drawbacks: More difficult installation, requires posting to the foundation 5

6 Online Image Sources: beams and ridge boards modern structural solutions for a frames/ Rafters with ceiling joists or rafter ties: Benefits: No posting required, field erected with manageable member sizes, cost effective Drawbacks: Limits design options (flat ceiling), limited ceiling spans, relies on proper connections Simple Roof Structure R802.3 R R R802.5 Footnotes If lapped R R Span based on horizontal projection (not length along slope) R802.5 Image: rafter ties.htm 6

7 Noted roof construction issues: Major Concept: Ridge board without ceiling joists Inadequate heel connection (workmanship) Inadequate ridge connection (workmanship) Inadequate header size (wall framing) Insufficient top plate splices (wall framing) Overdriven sheathing fasteners (wall/roof framing) Code Compliant Roof Design Options: 1. Structural ridge (by others/per IRC) Only option to achieve all desired results Requires reframing ridge, gable endwall and finding acceptable post locations 2. Prefabricated trusses (by others) Combination scissor and flat trusses Reduced slope interior cathedral ceiling in waterside room 3. Ceiling joists and rafter ties (per IRC) Raised flat ceiling in waterside room; no cathedral ceiling option Example: Using ceiling joists and rafter ties (IRC) Project Parameters 20 x 30 single story addition 20 x 16 waterside room 12 sliding door onto (future) deck Maximum height raised ceiling in waterside room Flat ceiling over bathroom/hallway (rear) Ceiling joists spliced over hallway/bathroom wall 6:12 roof slope (assumed) SPF #1/#2 grade material Ground snow load = 70 psf Dead load = 10 psf Uninhabitable attic with no storage IRC Sections R802.3 R802.5 and associated tables Table R802.4(1) Ceiling joist size for uninhabitable attic with no storage Table R (8) Rafter size for flat ceiling area Table R (8) with Footnote (a) Rafter size for raised ceiling area Table R (9) Rafter/ceiling joist heel joint connections for flat ceiling area Table R (9) with Footnotes (f) and (h) Rafter/ceiling joist heel joint connections for raised ceiling area Table R Rafter connection for uplift (not covered in example) 7

8 Table R (8) with Footnote (a) Rafter size for raised ceiling area H R = 5 based on 6:12 slope and 20 building width H C(max) = 1/3H R H C(max) = 1 8 Adjustment Factor = Spans in red = 0.67 * Tabulated value Flat lapped ceiling joists = 10 span 2x6 ceiling joist OK for both applications Raised ceiling joists = 2/3*20 =

9 Summary so far: Table R802.4(1) Table R (8) Table R (8) with Footnote (a) Ceiling joists: 2x6 min Rafter for flat ceiling area: 2x8 min Rafter for raised ceiling area: 2x12 min Maximum raised ceiling height = 1 8 Still to Do: Table R (9) Rafter/ceiling joist heel joint connections for flat ceiling area Table R (9) with Footnotes (f) and (h) Rafter/ceiling joist heel joint connections for raised ceiling area Table R Rafter connection for uplift (not covered in example) Image: rafter ties.htm Image: to/qa/ framing cathedral ceiling.aspx Actual roof pitch = 6:12 but footnotes do not say interpolation is allowed: Use most conservative result Connection required: (9) 16d nails per rafter/ceiling joist heel joint connection Footnote (e) requires same connection for lapped ceiling joists: (9) 16d nails Connection result above applies to ceiling joists only See additional footnotes for adjustments for rafter ties in raised ceiling area (next page) 2/3 of actual rafter slope = 4:12 results in (11) 16d nails for heel connection But still more on next page 9

10 Table R (9) with Footnote (f) and (h) Heel connection for raised ceiling area F S F V H C /H R = 1/3 Adjustment Factor = *11 = 16.5 Need (17) 16d nails at rafter tie to rafter connection in raised ceiling area F S F H F V Image: rafter ties.htm Roof slope greatly effects horizontal component forces F H Example: 12:12 roof slope F V = 500 lbs (given) F H = 500 lbs F S = 707 lbs F S F V F H Example: 4:12 roof slope F V = 500 lbs (given) F H = 1,500 lbs F S = 1,581 lbs Summary so far: Table R802.4(1) Table R (8) Table R (8) with Footnote (a) Table R (9) Table R (9) with Footnotes (f) and (h) Ceiling joists: 2x6 min Rafter for flat ceiling area: 2x8 min Rafter for raised ceiling area: 2x12 min Maximum raised ceiling height = 1 8 Rafter ceiling joist connection in flat ceiling area: (9) 16d nails Rafter rafter tie connection in raised ceiling area: (17) 16d nails Simpson hurricane clip for uplift (not covered in example) Calculation: 218 lbs* lbs/ft*0.67*1.33 ft = lbs req d See Simpson Tables 10

11 Maybe worth engineering fee! 2x10 at flat ceiling 2x12 not adequate at raised ceiling; use LVL rimboard? 1 8 Simpson clip for uplift (9) 16d nails at flat ceiling (9) 16d nails at flat ceiling (17) 16d nails at raised ceiling None 2x8 at flat ceiling 2x12 at raised ceiling 2x6 min Simpson clip for uplift Maybe not so simple! Code Compliant Roof Design Options: 1. Structural ridge (by others/per IRC) Only option to achieve all desired results Requires reframing ridge, gable endwall and finding acceptable post locations 2. Prefabricated trusses (by others) Combination scissor and flat trusses Reduced slope interior cathedral ceiling in waterside room 3. Ceiling joists and rafter ties (per IRC) Raised flat ceiling in waterside room; no cathedral ceiling option (17) 16d nails into a 2x6 rafter tie!!! Image: rafter ties.htm Nothing in table for 16 span Cannot approve based on IRC tables; Engineered design req d 11

12 Renderings by Valliere Design Studio How are you handling roof framing approvals currently? How do you document what is required (nailing, etc.)? CASE STUDY 1 ROOF DISCUSSION (5 10 MIN) Drawings by 2A Architects, LLC CASE STUDY 1 ROOF DISCUSSION (5 10 MIN) MUBEC & IRC APPLICABILITY & ADMINISTRATION IRC FLOORS QUESTIONS & ANSWERS PRESENTATION OUTLINE Floor framing (IRC) Chap. 5 JOISTS Table R (1): LL = 30 psf Residential sleeping areas only! L/ = 360 (minimum) Table R (2): LL = 40 psf Typical minimum load L/ = 360 (minimum) GIRDERS Table R502.5(1): Exterior bearing walls Provides spans & no. jack studs Table R502.5(2): Interior bearing walls Provides spans & no. jack studs EVERYTHING IS UNIFORM LOADING NO POINT LOADS! 12

13 IRC FLOORS QUICK EXAMPLE: 16 floor joists spaced 16 o.c.; Living room space with warm board (20 psf DL) IRC FLOORS QUICK EXAMPLE: Interior 3 2x10 support beam; Building width is 28 ; Supporting 2 floors; Determine maximum allowable span. MUBEC & IRC APPLICABILITY & ADMINISTRATION IRC FLOORS Wall Framing (IRC) Chap. 6 Figure R602.3(1): Typical Wall, Floor and Roof Framing PLATFORM FRAMING ONLY; NO BALLOON FRAMING PROVISIONS NO CATHEDRAL ENDWALL FRAMING PROVISIONS FOR SNOW LOAD OVER 25 PSF (ALL OF MAINE) EVERYTHING IS UNIFORM LOADING NO POINT LOADS! QUESTIONS & ANSWERS PRESENTATION OUTLINE 13

14 Wall Framing (IRC) Chap. 6 Figure R602.3(2): Framing Details PLATFORM FRAMING ONLY; NO BALLOON FRAMING PROVISIONS NO CATHEDRAL ENDWALL FRAMING PROVISIONS FOR SNOW LOAD OVER 25 PSF (ALL OF MAINE) Load bearing walls over 10 high require engineered design Section R EVERYTHING IS UNIFORM LOADING NO POINT LOADS! Wall Construction Notes Table R602.3(3) Requirements for Wood Structural Panel Wall Sheathing Used to Resist Wind Pressures This table is about positive and negative pressures against the wall sheathing. It is not related to braced wall requirements for shear transfer. Abbreviated Braced Wall Review Section R Wall bracing Table R Max Allowable Length of Wood Studs Exposed to Wind Speeds of 100 mph or less Footnote (b): Applicability of this table assumes the following: Snow load not exceeding 25 psf (i.e. not in Maine) Table R Wood structural panel box headers. Allowed but hard to identify as structural. Recommend avoiding if possible (maybe ) (maybe not ) Rendering (left) by 2A Architects, LLC Rendering (right) by Valliere Design Studio 14

15 Focus on Continuous Sheathing (CS) methods (R ) since these are most commonly used materials. Project Parameters 16 6 x ¾ story garage with living space on second level (knee walls) 8 w x 7 h garage door (re use existing) Basic wind speed = 100 mph In town Camden location No interior walls used as braced walls IRC Sections R and associated tables and figures Section R Length of bracing. Table R (1) Not less than 48 Section R Braced wall panel location. Figure R (1) Not more than 25 on center Figure R (2) Braced wall panel shall begin no more than 12.5 from the end of a braced wall line. The total combined distance from each end of a braced wall like to the outermost braced wall panel shall not exceed 12.5 Braced wall panels may be offset up to 4 from the designated braced wall line Total out to out offset of braced panels in a braced wall line shall not exceed 8 Rendering by 2A Architects, LLC 15

16 Adjustment factors: 1.0, 1.0, 0.95 therefore: At second floor: Min. total length ~4-9 along each braced wall line (CS method) At second floor: Minimum total length ~5 along each braced wall line (CS method) At first floor: Min. total length ~9-0 along each braced wall line (CS method) At first floor: Minimum total length ~9.5 along each braced wall line (CS method) but there are many footnotes for adjustment! What wall sections count and which don t? Rendering (top) by Valliere Design Studio Rendering (bottom) by 2A Architects, LLC Rendering by 2A Architects, LLC 16

17 Renderings by Valliere Design Studio Check garage door gable endwall: 16 6 x 23 8 single story garage 8 w x 7 h garage door (re use existing) 16 6 wall 8 0 door = 8 6 wall available 4 3 wall each side of garage door > 36 OK Total wall on garage door side at first floor = 8 6 < 9 0 NG Does everyone (i.e. anyone) fully understand braced wall provisions? Need to refine design, use alternate method, add interior braced wall, or have engineered design (shear wall). This is very basic presentation on braced walls and is not comprehensive. There is much more to know about IRC braced walls but it would take an entire course to cover it! Rendering by 2A Architects, LLC DISCUSSION MUBEC & IRC APPLICABILITY & ADMINISTRATION And how about those skinny walls? >5 Original construction IRC FLOORS Soil removed QUESTIONS & ANSWERS PRESENTATION OUTLINE This project is currently under construction right now; Foundation wall (left) is continuing to lean under vertical loads; Temporary posts have been added to support wall loads; Failed foundation wall to be replaced Exposed cracks 17

18 Footing Size Parameters Minimum Width of Footing, W, per Table R403.1 Minimum Footing Thickness, T = 6 (Min. 8 Preferred) Footing Projection, P shall be 2 and Thickness T Minimum Depth: 12 below undisturbed ground surface* Figure R403.1(1): Concrete and Masonry Foundation Details Concrete Foundation Wall Design Concrete Foundation Walls Tables R (1) R (9) (and the dozens of footnotes) R requires lateral support at the top and bottom of the wall. Drawing by 2A Architects, LLC QUICK EXAMPLE: Concrete wall restrained at top; 8 0 tall wall with 7 0 unbalanced backfill 18

19 Sample Foundation Wall Details Gartley & Dorsky IRC FOUNDATION 19

20 Maine Uniform Building & Energy Code (MUBEC) IRC What about stepped foundation walls (stem walls)? R : R Tables apply to foundation walls with laterally unsupported top conditions if walls support 48 of unbalanced backfill. R : Engineered design is required if unsupported foundation walls support > 48 of unbalanced backfill OR if walls are subject to hydrostatic pressure from groundwater. R Applied to original backfilled condition QUESTIONS? RESIDENTIAL STRUCTURAL SYSTEMS Carmen B. Bombeke, P.E. DISCUSSION TOPICS: USING SOFTWARE TO DETERMINE ITEMS NOT SPECIFIED IN IRC EDUCATING PUBLIC ON HOW TO BUILD IN COMPLIANCE WITH THE CODE OTHER IDEAS/CONCERNS RESIDENTIAL STRUCTURAL SYSTEMS Carmen B. Bombeke, P.E. Surveying Boundary Surveys and Research Topographic/As-built Surveys ALTA/ACSM Land Title Surveys Subdivisions Civil Engineering Roadway Design Hydrologic Analysis and Design Watershed Flood Studies Subdivisions Structural Engineering Structural Analysis & Design Building Inspections Construction Field Assistance Pier and Wharf Design Natural Resource & Soil Services Soils Surveys & Mapping Vernal Pool Identification Engineered Septic Systems Condominium Plats and Plans Elevation Certificates/LOMAs Hydrographic Surveys Construction Layout Land Development Engineered Sanitary Design Site Planning Shoreline Stabilization New Construction & Renovations Conditions Assessments Structural Detailing Historic Structures Site Evaluation Wetland Delineation Conventional Septic Systems Permitting Natural Resource Protection Act Permits Maine DEP Stormwater Permits Subdivision Planning Approvals Army Corps of Engineers Permits Maine DEP Site Location Permits Municipal Coordination 20