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Re: Two Family Dwelling Fire Separation
Chip,
That's a complicated question you've raised there ... "Two Family Dwelling " ...
*IF* it is a "two family dwelling" instead of a "townhouse" (there *IS* a difference), then the separation requirements are as follows:
From the 2004 FRC.
- 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 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.
- - - Exception: 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.
- - - R317.1.1 Supporting construction.
- - - - When floor assemblies are required to be fire-resistance-rated by Section R317.1, the supporting construction of such assemblies shall have an equal or greater fire-resistive rating.
You will notice that for "two family dwellings" the roof is not required to be protected, unlike they are for townhouses.
However, let's review your photos for problems with either "two family dwelling" or "townhouse".
First photo:
First and foremost, the roof sheathing (in a "townhouse" would be required to be either fire retardant treated (as your second photo shows it is) for a minimum distance of 4 feet to each side of the fire rated separation wall *measured from each face of the wall*, not measured from the center of the wall. From looking at your photo, that does not appear to be the case - the first two trusses look closer together, meaning that it is unlikely that the roof sheathing is fire retardant rated for 4 feet from the wall.
Also, I don't see where the roof sheathing has been staggered, which is required for all roofs, two family dwellings or townhouses, or any other type.
Now, though, there is yet another problem, and it affects both two family dwellings and townhouses, but it affects both differently.
*IF* the roof sheathing was required to be fire retardant treated (or otherwise protected), then *no openings are allowed with that first 4 feet* ... which includes ... *NO RIDGE VENT OPENINGS*.
That said, however, *IF* that is a two family dwelling, no fire retardant treatment is required, so the ridge vent opening is not a problem ... EXCEPT for where the opening crosses the separation wall.
Now, for two family dwellings, that wall is required to have a 1 hours fire resistance rating, and drywall on one side as that one was constructed only serves as a draft stop wall, it *is not* a 1 hour fire rated wall. Townhouses also require fire rated walls, except that the fire rated wall is now a 2 hour fire rated wall.
Now, for those outside Florida (Chip is in Florida), the IRC applies in most areas (and the FRC is based on the IRC). The IRC is similar, but different.
From the 2006 IRC.
- 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 1/2 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.
- - R317.1.1 Supporting construction. When floor assemblies are required to be fire-resistance-rated by Section R317.1, the supporting construction of such assemblies shall have an equal or greater fire-resistive rating.
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