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Discussion Starter · #1 ·
I am going to install 3/4" hardwood flooring on a ceiling. The ceiling is cathedral trusses 24" o/c. I am thinking of using 1/2" osb instead of drywall for the lids to hold the staples but I'm not sure on fire code. Anyone have some thoughts on this? Thanks.
 

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KemoSabe
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I've used fire rated plywood on many buildings, it may be worth a look.:thumbsup:
 

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topsail's trimcat
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i worked on a project similar to this a while back. only difference was it was 1x6 v groove pine instead of hardwood.

we were required to drywall the ceiling first then have 2 coats of mud on the seams and scews covered, then put up the v-groove
 

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Thom
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you don't say what the project is but if it's a residence a 3/4 hardwood should be fine without underlayment, just nail to the rafters.
 

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hurtlocker
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call building inspector he should have an answer right away
I have never put anything under wood applied to cieling on residential(besides vp or backing)
 

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Wood Craftsman
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nail to rafters????

you don't say what the project is but if it's a residence a 3/4 hardwood should be fine without underlayment, just nail to the rafters.

If I understand the individual that started the thread~ he is using "hardwood flooring" usually that is manufactured by variations~ you are going to need to install a sub sheathing if this is the case , you may need to put fire rated drywall on before you do anything, anyways~( I would use nothing less than 5/8" tg 4x8 ply sheathing ) "Mechanically fastened" ~" no nails" on to the Rafters~ remember you are upside down on this one~ It wants to pull away not settle down.
Have you had an architect look at what is being proposed~ you do have a weight factor being implemented into this. One problem you are going to have is your compression ~ the Pneumatic floor nailer's (as you know) drive the wood in at the same time the fastener is going in ~drawing the board tight ~ Just want you to be aware the product you are using is usually meant for the floor" obviously" is now going to the ceiling~ totally different animal. I would look into this ? :rolleyes:
 

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drywall isn't required. OSB is fine. The only criteria to meet for "fire code" is the smoke production rating which is true of any wall or cieling covering unless it's a fire wall, cieling over a garage beneath a sleeping area or otherwise specified as a fire wall
 

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Wood Craftsman
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Codes- not one size fits all.

They are not Cookie stamped every state, not including counties have different fire codes ~ so I am not aware of MI's FC codes~ just thought he may want to look into this. :thumbsup:
 

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Maker of fine kindling
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It was not required to drywall our guest house ceiling prior to a rustic resawn 1x8 wood ceiling. And I did not do it. That may be a local thing, I dunno.

But... I have had the thought that I wished I did to ensure the envelope was nice and tight. Seems like I could be losing heat through the cracks. But wtf?
 

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Discussion Starter · #15 ·
Thanks for the input. I do not have to drywall the ceiling first so my issue is that the hardwood flooring pieces are not long enough to just nail them into the trusses. I think I am going to glue and screw 1/2" osb and then glue and finish nail the tongue and grove flooring on the osb.
 

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Thanks for the input. I do not have to drywall the ceiling first so my issue is that the hardwood flooring pieces are not long enough to just nail them into the trusses. I think I am going to glue and screw 1/2" osb and then glue and finish nail the tongue and grove flooring on the osb.
I am not the expert here, but I have heard flooring guys prefer real plywood to osb. The nails bite much better.
 

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I am going to install 3/4" hardwood flooring on a ceiling. The ceiling is cathedral trusses 24" o/c. I am thinking of using 1/2" osb instead of drywall for the lids to hold the staples but I'm not sure on fire code. Anyone have some thoughts on this? Thanks.
check w/your architect and make sure your structure can hold the weight. generally my approach would be 5/8" plywood sheathing w/red-heads and diaphragm nail-pattern or min 3" o.c., 1/2" type-x scribed to form the arch, fire-tape, staple black-paper, and finishing-screws towed to your t&g flooring. my gut is you'll get a better look with dato-cut and custom-finish butt-board.
 

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KemoSabe
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It was not required to drywall our guest house ceiling prior to a rustic resawn 1x8 wood ceiling. And I did not do it. That may be a local thing, I dunno.

But... I have had the thought that I wished I did to ensure the envelope was nice and tight. Seems like I could be losing heat through the cracks. But wtf?
You will also get many years of accumulated dust falling down if you ever reroof. I highly recommend plywood backing with sealed seams at a minimum.:thumbsup:
 

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As stated above, OSB is all but useless for holding nails.

Personally, I would use longer planks than those boxes of random (too many shorts) planks have to offer. I'd mill the tounge and groove myself (or you could get it milled) and nail right to the rafters (I've done it before on an octagonal ceiling on a multi-million dollar guest house, the job was drawn up by Michael Graves, world-renowned architect).

The amount of end-seams that you can get away with on a floor will look way too busy on a ceiling, IMO.

You want it to look like a ceiling when it's done, - - not like an upside-down floor.

I don't know the size of the room or anything, but with trusses (which are generally flimsy) I'd consider adding some beef. With only 24" centers to begin with, it might be an option to center a new (in-between) run of real rafters.

I wouldn't rely on heavy plywood or OSB to stay straight over time on an upside-down application (even if happens to be straight to begin with, which is highly doubtful), especially with 24" centers. When used on a floor any eventual sag just floats under the joist plane.
 
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