# Combustionable Construction Attic 3000 Sq. Ft. Maximum Without Draftstop



## Mule (Jun 8, 2010)

I am having a total brain fart here. I know, or at least I think, in the 2006 IRC in combustionable construction there is a section of the code that specifies that....

In combustionable construction that the attic cannot be more than 3000 square feet without providing a draft stop. I have searched and searched and cannot find the requirement.

Please help me out and provide the section of the code that states this. I can see it in my mind that it is on the bottom left corner of a page but for tyhe life of me.....................

Am I dreaming this up??????? :roll:


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## Coug Dad (Jun 8, 2010)

It is Section 717.4 in the 2006 IBC.  Not sure if it is in the IRC.


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## Mule (Jun 8, 2010)

You know what.....I believe.....no...I'm sure my mind was in the wrong code! That's the code section I remember!! Ooops

Thanks Coug Dad for straightening me out!!


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## Coug Dad (Jun 8, 2010)

I did a word search of the 2006 for "draft" and "draftstop" and found no requirements.


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## TJacobs (Jun 9, 2010)

R502.12 = truss floor draftstop

R602.8 = wall fireblocking

---------- = roof truss draftstop


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## mtlogcabin (Jun 9, 2010)

Mule there is a requirement in the IRC just not exactly what you had in mind

R317.1 Two-family dwellings.

Dwelling units in two-family dwellings shall be separated from each other by wall and/or floor assemblies having not less than a 1-hour fire-resistance rating when tested in accordance with ASTM E 119. Fire-resistance-rated floor-ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend to the underside of the roof sheathing.

Exceptions:

1. A fire-resistance rating of ½ hour shall be permitted in buildings equipped throughout with an automatic sprinkler system installed in accordance with NFPA 13.

2. Wall assemblies need not extend through attic spaces when the ceiling is protected by not less than 5/8-inch (15.9 mm) Type X gypsum board and an attic draft stop constructed as specified in Section R502.12.1 is provided above and along the wall assembly separating the dwellings. The structural framing supporting the ceiling shall also be protected by not less than 1/2 -inch (12.7 mm) gypsum board or equivalent.


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## Coug Dad (Jun 9, 2010)

draftstopping is required in a single family dwelling only when there is usable space both above and below the combustible concealed space

R502.12 Draftstopping required.

When there is usable space both above and below the concealed space of a floor/ceiling assembly, draftstops shall be installed so that the area of the concealed space does not exceed 1,000 square feet (92.9 m2). Draftstopping shall divide the concealed space into approximately equal areas. Where the assembly is enclosed by a floor membrane above and a ceiling membrane below draftstopping shall be provided in floor/ceiling assemblies under the following circumstances:

1.   Ceiling is suspended under the floor framing.

2.   Floor framing is constructed of truss-type open-web or perforated members.


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## FredK (Jun 10, 2010)

Like cougardad said: Unless you got usable space above or below draftstopping isn't required in a SRF IMHO.


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## Coug Dad (Jun 10, 2010)

above *and* below, not above *or* below


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## Mule (Jun 11, 2010)

Thanks for the responses and the discussion.


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