Thread: Attic is sheathed in plywood

I have an inspection lined up for a 1970's townhouse. The attic appears to be completely sheathed in with plywood.
I think there should be drywall fire separation between the units.
I will have to check for sufficient ventilation.

Does anyone know of other potential problems? I'm thinking it's unusual and may have been done without permission.

Similar Threads:

• Attic access problems
• Hi/Low vents terminate in the attic?!
• Short Attic Ladder
• From the old board, Plywood Patio & Plywood Sidewalk
• Protection of wiring in the attic

Some fire separation would be nice... it's hard to say what was required. The exact build date might shed some more light.

When people cover all the interior surfaces of the attic they usually disrupt the intended ventiation too. In my experience it's usually accompanied by a bunch of outlets and light fixtures Did you see any loose stems or seeds?

I would report that I was unable to verify the presence of a firewall. Always report what you see and be careful not to presume what you can't see. If that makes sense!

Originally Posted by John Kogel

I have an inspection lined up for a 1970's townhouse. The attic appears to be completely sheathed in with plywood.
I think there should be drywall fire separation between the units.

Whether that was constructed in the 1950s or last year, the fire is going to spread just as rapidly across that plywood. Wouldn't you agree?

Thus, whether or not it was "required" or not does not (should not) matter as you would be writing it up anyway - The wall between the townhouse units should be a fire-resistance rated wall, which would typically include 5/8" Type X drywall on each side of the wall, the other side of the wall is not visible, however, this side of the wall is visible in the attic and is covered with plywood. Additionally, the roof sheathing should be protected with 5/8" Type X drywall for a minimum of 4 feet from each side of the wall.

Can they just add a layer of 5/8" Type X drywall to each side of that common wall? Sure, but that would not make it a 2-hour rated wall, but it would definitely help.

Can they add a layer of 5/8" Type X to the underside of the plywood under the roof sheathing out at least 4 feet from the wall?, Sure, but I would have it go past the next truss out beyond the 4 foot minimum. Will this help? Yes, but the wall still would need to be addressed too, and don't forget that the drywall would not be 'attached to the plywood' ceiling but would need to be attached to the trusses, meaning drywall screws/nails long enough to go through the plywood and into the trusses would need to be used.

Originally Posted by Jerry Peck

Whether that was constructed in the 1950s or last year, the fire is going to spread just as rapidly across that plywood. Wouldn't you agree?

Thus, whether or not it was "required" or not does not (should not) matter as you would be writing it up anyway - The wall between the townhouse units should be a fire-resistance rated wall, which would typically include 5/8" Type X drywall on each side of the wall, the other side of the wall is not visible, however, this side of the wall is visible in the attic and is covered with plywood. Additionally, the roof sheathing should be protected with 5/8" Type X drywall for a minimum of 4 feet from each side of the wall.

Can they just add a layer of 5/8" Type X drywall to each side of that common wall? Sure, but that would not make it a 2-hour rated wall, but it would definitely help.

Can they add a layer of 5/8" Type X to the underside of the plywood under the roof sheathing out at least 4 feet from the wall?, Sure, but I would have it go past the next truss out beyond the 4 foot minimum. Will this help? Yes, but the wall still would need to be addressed too, and don't forget that the drywall would not be 'attached to the plywood' ceiling but would need to be attached to the trusses, meaning drywall screws/nails long enough to go through the plywood and into the trusses would need to be used.

Thanks, Jerry. I'm fine with the wall requirement, but even in new construction, I never see the ceiling, usually open frame and roof sheathing, never covered with drywall. Different requirements I imagine.
PS, The small pic was copied from MLS.

Does plywood OVER the drywall void the protection?

Does plywood OVER the drywall void the protection?

Not that I am aware of....

No it doesn't void the protection.However, it is usually two layers of 5/8" type X, staggered seams, independantly taped and mudded on both sides of a stud frame wall along with gyp lined roof structure 4' in for a rated assembly. IIRC the roof lining wasn't until after 1970 - as "townehomes" could be built to two different standards - IF no platted land beyond house line or building surrounded/isolated from public through-way by common held land.For all we know there is a masonry structural wall between the units and its proud of the roof deck. In that event - no gyp is required, just fire/draft blocking.It might also have been built as a multi-tenancy originally with out rated "fire walls" just Separations.Might also be lined with FRT plywood.Could very well be a truss design with lined storage-in-truss.May be attic space over protruding garage structure or living space - without a common wall to a neighbor. Might be the "end" unit on a row too, and the gable is the end of the building/row. Never know with MLS pictures what/where they are showing untill you see the property yourself.

Thanks, everybody. There turned out to be some weird design anomalies but the attic was not one of them, no common walls in that portion of the unit.

Originally Posted by John Kogel

Thanks, everybody. There turned out to be some weird design anomalies but the attic was not one of them, no common walls in that portion of the unit.

Ah ha...as I suspected: no common wall or connection. Well there you go, can't assume anything from photos on a listing.

Also, keep in mind how the IRC defines an "attic." You might want to describe this as a third floor [or second, depending on the rest of the building.]


From the '06 code: ATTIC.

The unfinished space between the ceiling joists of the top story and the roof rafters.

Originally Posted by erika krieger

Also, keep in mind how the IRC defines an "attic." You might want to describe this as a third floor [or second, depending on the rest of the building.]


From the '06 code: ATTIC.

The unfinished space between the ceiling joists of the top story and the roof rafters.

And before you call that anything other than an attic, keep in mind that it is not habitable space of any type, so *as most* it would be 'storage'.

Also, lining it with plywood does not, in my opinion, make it "finished" space as "finished" space would require proper electric, heat, etc., within the thermal envelope of the structure.

Originally Posted by Jerry Peck

And before you call that anything other than an attic, keep in mind that it is not habitable space of any type, so *as most* it would be 'storage'.
Also, lining it with plywood does not, in my opinion, make it "finished" space as "finished" space would require proper electric, heat, etc., within the thermal envelope of the structure.

Before this thread gets hijacked by another pi$$ing match between me and JP, I'll qualify my previous remark: it has nothing to do with thermal envelope [can't tell that from the picture anyway,] habitable, non-habitable, heat, electric; here in NY we would not call that an attic, it would be the top story. Perhaps it's the same in some of your jurisdictions; it wouldn't hurt to ask.

Originally Posted by John Kogel

I have an inspection lined up for a 1970's townhouse. The attic appears to be completely sheathed in with plywood.
I think there should be drywall fire separation between the units.
I will have to check for sufficient ventilation.

Does anyone know of other potential problems? I'm thinking it's unusual and may have been done without permission.

Only that if it was drywall you would be asking almost the same questions except for,''fire proofing and heat build up.''
You can not inspect rafters and all roofing systems now and are left to use a IR camera to get behind for evaluation of whats in-place.

Originally Posted by John Kogel

I have an inspection lined up for a 1970's townhouse. The attic appears to be completely sheathed in with plywood.
I think there should be drywall fire separation between the units.
I will have to check for sufficient ventilation.

Does anyone know of other potential problems? I'm thinking it's unusual and may have been done without permission.

Only that if it was drywall you would be asking almost the same questions except for,''fire proofing and heat build up.''
You can not inspect rafters and all roofing systems now and are left to use a IR camera to get behind for evaluation of whats in-place.
I was also wondering could you please describe all the systems in-play here.
1> I see chimney,and is it block, brick, or per cast chimny blocks.
2> piping is for what
3> seems to be a hatch at rear of the attic near the gable.
If fire code accepts ''the wood ply'' would it not have to be 1.1/4 inches of sold wood as separation between homes acting as fire break.
Can not see fire brick.
I am just asking out of curiosity for I can not make out the photo well here.
Thanks..