AWC & NAHB Author Original Code Change Proposals Effectively Banning Floor Truss and I-joist Use

Editor’s Note: SBC Industry News has recently shared a series of firefighter-related news items that has made us reflect on the IRC code change proposal effectively altering the competitive landscape with respect to the use of trusses and I-joists in residential markets where basements are standard. The news items contained in this SBC Industry News-Special Edition! provide a retrospective on the facts surrounding the need for a ½ inch gypsum wallboard membrane to be applied to everything but 2x10 floor joists that became part of the 2012 International Residential Code (IRC). It is clear this code change has altered the free market to favor 2x10s, where all other structural floor member alternatives now have to add a gypsum ceiling and are therefore more expensive. This is important news from a public policy point of view so we have included hyperlinks to other recent, related news items, which can be found at the bottom of the page.

Initial Code Proposal

This is the original code change proposal that started a non-science based threat to the wood truss and I-joist markets:

RB31-09/10

R302.7 (New), R502.14 (New), Table R502.14 (New)
Proposed Change as Submitted

Proponent: Dennis Pitts, American Forest and Paper Association (currently known as American Wood Council (AWC))

Add new text and table as follows:

R302.7 Floors. Floor assemblies, not required elsewhere in this code to be fire resistance rated, shall be provided with a ½ inch (12.7 mm) gypsum wallboard ceiling membrane.

Exception:
1. Floor assemblies protected by an automatic sprinkler system in accordance with NFPA13, NFPA 13R, NFPA13D, or Section R313.
2. Floor assemblies having a minimum fire resistance of 15 minutes, supporting at least 50% of the full design load, and complying with one of the following:
2.1. Tested in accordance with ASTM E119 or UL 263, or;
2.2. Determined in accordance with International Building Code Section 721.
3. Floor assemblies located directly over a crawl space.
4. Floor assemblies complying with Section R502.14.
5. A portion of a floor assembly area not greater than 100 square feet per story.

R502.14 Fire resistant assemblies. Wood floor assemblies shall comply with the provisions of Section R302.7 or any one of the following:
1. Wood floor assemblies using dimension lumber equal to or greater than 2 inches in thickness by 8 inches in width, nominal.
2. Wood floor assemblies using structural composite lumber, complying with ASTM D5456, equal to or greater than 1 ½” in thickness by 7 ¼” in width.
3. Wood floor assemblies having a minimum fire resistance time of 15 minutes determined from any of the following options or the sum of the times from any combination thereof:
3.1. Time assigned to a ceiling membrane or membranes in Table 502.14.
3.2. Finish rating time for a ceiling membrane not listed in 502.14.
3.3. Time to structural failure of framing members, supporting at least 50% of the full design load, and complying with one of the following:
3.3.1. Tested in accordance with ASTM E119 or UL 263, or;
3.3.2. Determined in accordance with International Building Code Section 721.

Reason: The fire service has asked for minimum fire resistance of floor/ceiling systems equivalent to 2x lumber floor construction. The basis of the requirements assume that a floor/ceiling assembly constructed using 2x lumber and loaded to 50% of full design load will provide 15 minutes of structural fire resistance as confirmed by recent UL testing reported in Structural Stability of Engineered Lumber in Fire Conditions.

The proposed R302.7 provides a simple method of meeting this 15 minute requirement for all floor assemblies by requiring ½” gypsum wallboard as a protective ceiling membrane. Exceptions to this requirement are provided.

Adopted Code Proposal

What follows is the final code change proposal adopted through the negotiating efforts of NAHB and AWC, who were unconcerned about the impact a code change like this would have on free market competition:

RB87-09/10

R501.3 (New)
Proposed Change as Submitted

Proponent: Sean DeCrane, Cleveland, OH Fire Department, representing the International Association of Fire Fighters

Add new text as follows:

R501.3 Fire floor protection. Floors within dwelling units utilizing light-frame construction shall be protected on the underside by a minimum of 5/8” gypsum board applied in accordance with Section R702.3.

Exceptions:
1. Crawl spaces where the maximum clear height from the underside of the subfloor to the void space floor is 3 feet or less and is not intended for mechanical equipment use or storage.
2. The building is protected with an automatic sprinkler system designed to NFPA 13D or Section P2904 of this code.
3. Floors in which the exposed materials are protected by materials achieving a 30-minute fire-resistance rating in accordance with ASTM E 119 or UL 263.

Reason: On August 13, 2006 a Wisconsin fire fighter was killed, and a second fire fighter injured, when the floor they were operating on collapsed sending them into the basement. One fire fighter fell directly into the room of origin and was killed, the second fire fighter landed on the opposite side of a block wall and survived by shielding herself and making an escape through a rear window. They checked the floor to ensure it was safe and solid, just prior to collapse they heard a loud crack. The floor they were operating on was unprotected lightweight construction that collapsed without warning. In the ensuing investigation, the National Institute for Occupational Safety and Health released report F2006-261. One of the recommendations is to “modify current building codes to require that lightweight trusses be protected with a fire barrier”. This should not only pertain to truss construction. There are additional forms of construction that can be determined to be lightweight, cold form steel, bar joists, wooden engineered I-beam, etc., the recent trend in residential construction is to use products that are financially beneficial. It is the belief of many of us in the fire service that as the industry engineers products to a more finite point we are losing our safety factors…

Individual Consideration Agenda
This item is on the agenda for individual consideration because public comments were submitted.

Public Comment 1:

Sean DeCrane, Cleveland, OH, Fire Department, representing the International Association of Fire Fighters; Azarang (Ozzie) Mirkhah, Las Vegas, NV, Fire & Rescue, representing Fire & Life Safety Section of the International Association of Fire Chiefs); Steven Orlowski, National Association of Home Builders, Dennis Pitts, American Wood Council, American Forest & Paper Association, requests Approval as  Modified by this Public Comment.

Replace proposal as follows:
R501.3 Fire protection of floors. Floor assemblies, not required elsewhere in this code to be fire resistance rated, shall be provided with a ½ inch gypsum wallboard membrane, 5/8 inch wood structural panel membrane, or equivalent on the underside of the floor framing member.

Exceptions:
1. Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section P2904, NFPA13D, or other approved equivalent sprinkler system.
2. Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances.
3. Portions of floor assemblies can be unprotected when complying with the following:
3.1 The aggregate area of the unprotected portions shall not exceed 80 square feet per story
3.2 Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.
4. Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.

Commentor’s Reason: This public comment was developed in response to the IRC Code Development Committee’s comments regarding RB3, RB85, RB86, RB87 and RB88.

Resulting 2012 IRC Model Code Language

Related Articles: