Thread: Fire separation between Townhouses.

Good Morning.

What are the provisions for a firewall in a single story end unit townhouse next to a two story townhouse? The attic roof was covered with sheetrock. I am concerned about the common wall even though it does not go attic to attic.

Jim Murphy

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Photos would help. I assume you mean the attic ceiling was covered with sheetrock.

Typical fire separation requirements for townhouses is a 2 hour fire rating. 8" thick masonry was a common way to do firewalls in my area. Gypsum board party walls are more common now. They are typically 2" thick. I think 1/2" thick gypsum board is probably also required at each side (on the wall framing adjacent to the 2" shaft liner system).

What was visible on the common wall in the attic?

Originally Posted by JIM MURPHY

What are the provisions for a firewall in a single story end unit townhouse next to a two story townhouse? The attic roof was covered with sheetrock.

The entire underside of the roof, 4 feet out from the wall, or ???

I am concerned about the common wall even though it does not go attic to attic.

Typically there are two options, the 2 hour rated wall as Mark mentioned, or basically two halves of 1 hour rated walls with no penetrations (or course, though, that mean no receptacles on those walls, no plumbing pipes, no anything, so that is not too common to find).

However, you will not know anything about the rating of the common wall from looking at it once it has been constructed, except for the part which (in your case) separates the attic of the one story townhouse from the two story townhouse. In the case of that wall, you might be able to determine that it is not constructed properly (by seeing things you should not be seeing), but you would not be able to determine that it was constructed properly (because you would not be able to see the things you would need to see).

It would be like watching two cars driving down a highway - you could say that one car was going faster than the other, but you would not be able to state that both were within the speed limit based on just watching them and not using any tools, calculations, or a radar gun ... just two cars driving down the highway and one is going faster than the other - which does not really tell you much useful information.

The attic roof was covered in sheetrock as shown and here is a picture of the common wall




2015-06-10 06.09.49.jpg2015-06-10 06.11.40.jpg

- - - Updated - - -

The attic roof was covered in sheetrock as shown and here is a picture of the common wall




2015-06-10 06.09.49.jpg2015-06-10 06.11.40.jpg

Jim,

Is that OSB wall in the attic photos the wall to the adjacent townhouse?

If so, and if that was one part of your question, no, there is nothing shown on it which indicates it is a proper rated wall between the two, first and foremost, you would most likely be looking at 5/8" Type X instead of OSB if that were a properly rated wall.

Additionally, back to the roof, I believe that the protection is required to extend outward a minimum of 4 feet from the common wall in a configuration such as that, and the protection is not (as I recall, I would need to verify it) just for the roof sheathing but for the roof (which includes the structure - trusses). I would need to look up the wording in the code to verify what needed protection for 4 feet out.

Jerry, yes that is OSB which led me to the conclusion that it was not a proper firewall even though it is a single floor end unit sitting next to a two story unit. I guess it is possible that on the other side of this wall they built a correct firewall to cover both units. However, we cannot see it.

I have really opened a large can of worms here. The original inspector which did a prelisting inspection says that it does not have to be a firewall because it is one story. The complex is 7 years old built by Ryland. I guess that would be the 2005 code? I have everyone flipping out about this. Anymore help would be great. I imagine we will have to throw it back to the builder and let them prove it was built right!

The protection for the roof is 4' from the common wall. Not sure why they did the whole roof.

Jim

Originally Posted by Jerry Peck

Jim,

Is that OSB wall in the attic photos the wall to the adjacent townhouse?

If so, and if that was one part of your question, no, there is nothing shown on it which indicates it is a proper rated wall between the two, first and foremost, you would most likely be looking at 5/8" Type X instead of OSB if that were a properly rated wall.

Additionally, back to the roof, I believe that the protection is required to extend outward a minimum of 4 feet from the common wall in a configuration such as that, and the protection is not (as I recall, I would need to verify it) just for the roof sheathing but for the roof (which includes the structure - trusses). I would need to look up the wording in the code to verify what needed protection for 4 feet out.

I'll look somethings up later, but a fire rated wall between townhouses is rated for protection against fire from both sides of the wall - not just one from one side.

Any help possible would be appreciated. I looked up the code in the 2006 IRC section R317. Not sure I understand it. I am just an inspector, not a code enforcer. By the way, these units were built in 2008.

Jim

Originally Posted by Jerry Peck

I'll look somethings up later, but a fire rated wall between townhouses is rated for protection against fire from both sides of the wall - not just one from one side.

It does not look correct, but I suppose there is a chance that it is. I don't know what 1-story has to do with anything.

Only the roof sheathing needs to be fire-resistant withing 4' of the party wall, not the trusses. There are some situations (usually in commercial buildings) where fire-resistant trusses are required, but I am not familiar with those requirements.

From the IRC: (you would need to verify what code was in effect at the time of construction, but this is a good current guideline) (bold and underlining are mine)
- R302.2 Townhouses.
- - Each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls.
- - - Exception: A common 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E 119 or UL 263 is permitted for townhouses if such walls do not contain plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be installed in accordance with Chapters 34 through 43. Penetrations of electrical outlet boxes shall be in accordance with Section R302.4.
- - R302.2.1 Continuity.
- - - The fire-resistance-rated wall or assembly separating townhouses shall be continuous from the foundation to the underside of the roof sheathing, deck or slab. The fire-resistance rating shall extend the full length of the wall or assembly, including wall extensions through and separating attached enclosed accessory structures.
- - R302.2.2 Parapets.
- - - Parapets constructed in accordance with Section R302.2.3 shall be constructed for townhouses as an extension of exterior walls or common walls in accordance with the following:
- - - - 1. Where roof surfaces adjacent to the wall or walls are at the same elevation, the parapet shall extend not less than 30 inches (762 mm) above the roof surfaces.
- - - - 2. Where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is not more than 30 inches (762 mm) above the lower roof, the parapet shall extend not less than 30 inches (762 mm) above the lower roof surface.
- - - - - Exception: A parapet is not required in the two cases above when the roof is covered with a minimum class C roof covering, and the roof decking or sheathing is of noncombustible materials or approved fire-retardant-treated wood for a distance of 4 feet (1219 mm) on each side of the wall or walls, or one layer of 5/8-inch (15.9 mm) Type X gypsum board is installed directly beneath the roof decking or sheathing, supported by a minimum of nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members, for a minimum distance of 4 feet (1219 mm) on each side of the wall or walls and there are no openings or penetrations in the roof within 4 feet (1219 mm) of the common walls.
- - - - 3. A parapet is not required where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is more than 30 inches (762 mm) above the lower roof. The common wall construction from the lower roof to the underside of the higher roof deck shall have not less than a 1-hour fire-resistance rating. The wall shall be rated for exposure from both sides.
- - R302.2.3 Parapet construction.
- - - Parapets shall have the same fire-resistance rating as that required for the supporting wall or walls. On any side adjacent to a roof surface, the parapet shall have noncombustible faces for the uppermost 18 inches (457 mm), to include counterflashing and coping materials. Where the roof slopes toward a parapet at slopes greater than 2 units vertical in 12 units horizontal (16.7-percent slope), the parapet shall extend to the same height as any portion of the roof within a distance of 3 feet (914 mm), but in no case shall the height be less than 30 inches (762 mm).
- - R302.2.4 Structural independence.
- - - Each individual townhouse shall be structurally independent.
- - - - Exceptions:
- - - - - 1. Foundations supporting exterior walls or common walls.
- - - - - 2. Structural roof and wall sheathing from each unit may fasten to the common wall framing.
- - - - - 3. Nonstructural wall and roof coverings.
- - - - - 4. Flashing at termination of roof covering over common wall.
- - - - - 5. Townhouses separated by a common 1-hour fire-resistance-rated wall as provided in Section R302.2.

It is what I don't see in those photos, some of which is underlined and in bold.

Thank you Jerry for your time. I now believe I have enough information to support my claim. If they want to rebuttal then they can contact the builder and the architect.

Jim

Originally Posted by Jerry Peck

From the IRC: (you would need to verify what code was in effect at the time of construction, but this is a good current guideline) (bold and underlining are mine)
- R302.2 Townhouses.
- - Each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls.
- - - Exception: A common 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E 119 or UL 263 is permitted for townhouses if such walls do not contain plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be installed in accordance with Chapters 34 through 43. Penetrations of electrical outlet boxes shall be in accordance with Section R302.4.
- - R302.2.1 Continuity.
- - - The fire-resistance-rated wall or assembly separating townhouses shall be continuous from the foundation to the underside of the roof sheathing, deck or slab. The fire-resistance rating shall extend the full length of the wall or assembly, including wall extensions through and separating attached enclosed accessory structures.
- - R302.2.2 Parapets.
- - - Parapets constructed in accordance with Section R302.2.3 shall be constructed for townhouses as an extension of exterior walls or common walls in accordance with the following:
- - - - 1. Where roof surfaces adjacent to the wall or walls are at the same elevation, the parapet shall extend not less than 30 inches (762 mm) above the roof surfaces.
- - - - 2. Where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is not more than 30 inches (762 mm) above the lower roof, the parapet shall extend not less than 30 inches (762 mm) above the lower roof surface.
- - - - - Exception: A parapet is not required in the two cases above when the roof is covered with a minimum class C roof covering, and the roof decking or sheathing is of noncombustible materials or approved fire-retardant-treated wood for a distance of 4 feet (1219 mm) on each side of the wall or walls, or one layer of 5/8-inch (15.9 mm) Type X gypsum board is installed directly beneath the roof decking or sheathing, supported by a minimum of nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members, for a minimum distance of 4 feet (1219 mm) on each side of the wall or walls and there are no openings or penetrations in the roof within 4 feet (1219 mm) of the common walls.
- - - - 3. A parapet is not required where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is more than 30 inches (762 mm) above the lower roof. The common wall construction from the lower roof to the underside of the higher roof deck shall have not less than a 1-hour fire-resistance rating. The wall shall be rated for exposure from both sides.
- - R302.2.3 Parapet construction.
- - - Parapets shall have the same fire-resistance rating as that required for the supporting wall or walls. On any side adjacent to a roof surface, the parapet shall have noncombustible faces for the uppermost 18 inches (457 mm), to include counterflashing and coping materials. Where the roof slopes toward a parapet at slopes greater than 2 units vertical in 12 units horizontal (16.7-percent slope), the parapet shall extend to the same height as any portion of the roof within a distance of 3 feet (914 mm), but in no case shall the height be less than 30 inches (762 mm).
- - R302.2.4 Structural independence.
- - - Each individual townhouse shall be structurally independent.
- - - - Exceptions:
- - - - - 1. Foundations supporting exterior walls or common walls.
- - - - - 2. Structural roof and wall sheathing from each unit may fasten to the common wall framing.
- - - - - 3. Nonstructural wall and roof coverings.
- - - - - 4. Flashing at termination of roof covering over common wall.
- - - - - 5. Townhouses separated by a common 1-hour fire-resistance-rated wall as provided in Section R302.2.

It is what I don't see in those photos, some of which is underlined and in bold.