Wood-Framed, Exterior Walls in Type III Construction

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1 Wood-Framed, Exterior Walls in Type III Construction with Engineered Wood Product Floor Framing Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board.

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3 Course Description With the trend toward increased density, more designers are choosing Type III Construction in order to achieve greater heights and areas for their mid-rise wood-framed projects. This presentation will review 2015 IBC provisions for wood-framed exterior walls in Type III buildings as compared to Type V. Discussion will include how to maintain the intent of the code at the wall-to-floor intersections in scenarios that include wood-framed walls and engineered wood floors. Details illustrating the importance of correct rim specification when using platform framing and for semi-ballooned framed walls will also be provided.

4 Objectives CBC provision differences between Type V and Type III construction. 2. Definition of fire-retardant-treated (FRT) wood, what materials can be treated, and reductions to design properties due to treatment. 3. Required fire-resistance ratings and maintaining those ratings at the wall to floor intersection. 4. Structural significance of proper rim specification with platform framing and detailing for semi-ballooned framed walls.

5 Architectural Details Structural Details

6 Use and Occupancy Classifications Residential Group R CBC Section 310 R1 R2 R3 R4

7 Type of Construction Type IV Fire Resistance Requirements Type I & II Size of Building TYPE V TYPE IV TYPE III TYPE II TYPE I Type of Construction Fire Resistance Type III Type V

8 Type Of Construction 2016 CBC Chapter 5, General Building Heights and Areas Section Height

9 Type Of Construction 2016 CBC Chapter 5, General Building Heights and Areas Section Stories Check Local Code Amendments City of Seattle allows 5 stories for Type V

10 Type Of Construction 2016 CBC Chapter 5, General Building Heights and Areas Section Area

11 Some exceptions Section Mezzanines (no. of stories) Part of story below Shall not exceed 1/3 the floor area it is occupying Section Frontage Increase (allowable area) More area permitted when access to public way 25% of building perimeter on public way Public way or open space at least 20 ft wide Section Group R-1 and R-2 buildings of Type III A construction Increase to 6 stories with increase in fire protection

12 Materials Allowed for Types of Construction Type V Section Any material permitted by code Most common for EWP Type III Section Non-combustible exterior walls or Fire-retardant treated (FRT) wood allowed Interior building elements any material permitted by code Check Local Code Amendments

13 FRT Wood 3 Pathways to FRTW 1. CBC Pressure Process 2. CBC Other means during manufacture. The use of paints, coatings, stains or other surface treatments are not an approved method of protection as required in this section. 3. CBC Section Alternative materials, design, and methods

14 FRT Wood Testing Flame Spread index of 25 or less (10 min) PLUS Extended ATSM E 84 (30 min) No evidence of significant progressive combustion Flame front shall not progress more than 10.5 ft Class A Flame Spread FRT Strength Adjustments Factors Wood Structural Panels Lumber Labeled

15 FRT Wood Evaluation Reports for FRT Chemicals Lumber Plywood Species Strength Reductions Corrosion Fastener Reductions

16 FRT Wood Platform Framing Challenge: Most SCL/GLB: not evaluated after FRT Dimensional changes SCL/GLB not warranted after pressure treatment Check with SCL/GLB manufacturer

17 Fire-Resistance Ratings for Building

18 Fire-Resistance Ratings for Building

19 Fire-Resistance Rated Assemblies CBC Section Methods for determining fire resistance. Established by 1. Designs per approved sources 2. Prescriptive per Section Calculated per Section Engineering analysis based on ASTM E 119 or UL Alternative means per Section Certified Designs

20 Fire-Resistance Rated Assemblies Resources: International Building Code Intertek Underwriters Laboratories Gypsum Association Manufacturer s literature/code evaluation reports American Wood Council (DCA3) APA (D350A)

21 Fire-Resistance Rated Assemblies What are the requirements when the floor framing intersects the exterior wall? 2 hr FRT 1 hr 1 hr

22 Semi-Ballooned Framed Walls Things to consider Hangers Taller Studs Scheduling trades Design considerations Connections Eccentricity Not preferred

23 Platform Framed Walls Things to consider Preferred Eliminate Hangers Consistent Stud Heights

24 Platform Framed Walls Section 705 Exterior Walls Structural stability. Band joist to be of fire-resistant construction Equivalent fire resistance to the wall Floor joists do not require fire-resistance equal to the wall See Table 601 Rating to Rim = ceiling rating + direct applied protection

25 Platform Framed Walls Type IIIA Wall - 2-hr Floor - 1-hr Additional 1-hr protection required for rim to total 2-hr rating Type IIIB Wall 2 hr Floor 0-hr Direct applied 2-hr protection required

26 Platform Framed Walls APA wall details D350A Ceiling Membrane + Direct Applied Protection Rim Board Protection

27 Platform Framed Walls Interek Listing 4. Rim Board Protection: Direct-applied protection listed in table, items A-E.

28 FRT Wood Is rim part of the wall framing? Does rim need to be FRT wood?

29 Rim Specification Critical Structural Component Transfer vertical loads Transfer lateral loads Compatible with I-Joists Same depth as I-joist or slightly greater Maintain depth compatibility CBC Section Conform to ANSI/APA PRR 410 or ASTM D 7672 Depth compatibility

30 Framing Details Options? Wide rim with joist hangers Check with EWP manufacturer s for proprietary solutions AC124 Acceptance Criteria for Rim Board Products Section 7.0 Factory-Applied Fire-Retardant Overlaid or Coated Rim Board for Interior Applications

31 Review Differences between Type V and Type III construction FRTW or equivalent at exterior walls 2-hr fire-resistance rated walls FRT wood Dimension Lumber or Plywood have been evaluated Class A Flame Spread FRT Fire-resistance ratings Type III exterior rim 2-hr fire-resistance rating Total rating = ceiling protection + rim protection 2 layer ceiling for EWP joists Details Platform framing proper rim specification Semi-ballooned framed walls - hangers

32 Questions? This concludes the American Institute of Architects Continuing Education System Program Renee Strand, P.E Weyerhaeuser