garage ceiling waves

[gcan]

Some advise for others - I just completed my 2 car detached garage and used 4'x8' sheets of 3/8" plywood on the ceiling with lattice strips covering the joints and creating 4'x4' grid look on the ceiling. Looked great when I installed but later had two problems:
1) the inspector turned down the final inspection because of the plywood, said it should have been fire rated sheetrock due to the 12'x26' room overhead. With a lot of talking and explaining that the room is only for storage, right, got him to give me a pass on the inspection
2) now the plywood has waves, I secured with sheetrock screws every 12 inches around the perimeter and at the midway point when installing but it developed waves. I would consider replacing but I blew insulation in the overhead, after installing the plywood and before installing the floor in the upstairs room. Man what a mess that would be

Man I'm pissed....two reasons 1) I felt the inspector should have mentioned the ceiling needed to be sheetrock, on one of his numerous visits and 2) the garage looks great until you look up and see the waves

Hope others learn from my mistake

good luck

 

[thefairlaneman]

Some advise for others - I just completed my 2 car detached garage and used 4'x8' sheets of 3/8" plywood on the ceiling with lattice strips covering the joints and creating 4'x4' grid look on the ceiling. Looked great when I installed but later had two problems:
1) the inspector turned down the final inspection because of the plywood, said it should have been fire rated sheetrock due to the 12'x26' room overhead. With a lot of talking and explaining that the room is only for storage, right, got him to give me a pass on the inspection
2) now the plywood has waves, I secured with sheetrock screws every 12 inches around the perimeter and at the midway point when installing but it developed waves. I would consider replacing but I blew insulation in the overhead, after installing the plywood and before installing the floor in the upstairs room. Man what a mess that would be

Man I'm pissed....two reasons 1) I felt the inspector should have mentioned the ceiling needed to be sheetrock, on one of his numerous visits and 2) the garage looks great until you look up and see the waves

Hope others learn from my mistake

good luck

More than likely the cause is moisture. You see plywood that is unsealed is very much affected by uneven moisture.

 

[PAToyota]

Just playing devil's advocate, but if you take on the responsibility of building yourself you are responsible for knowing what the codes are. The inspector isn't there to educate you. Frankly, he just doesn't have the time.

Now, if you had asked him if you could put plywood up that would be a different matter. But he cannot be expected to ask you everything to make sure that you intend to do it the right way.

The issue you have now is that if there is ever a problem with a fire at any point, your insurance will likely not pay out because the building was not built to code.

Too late now, but one thing you could have done would have been to paint both sides of the plywood to better seal it in order to help with the moisture induced warping.

 

[rodnok1]

You could take it down and reuse the insulation and put drywall up, you could use a screen material or something similiar to hold it up, do a strip put insulation in...I doubt if the insurance company would not pay out since it did pass inspections.
You're gonna find most inspectors overwhelmed and cannot keep track of what you are doing, Gotta love the part you sign saying it will be build to code. You would think most plans would be gone over prior to permits being issued, but they gave me my building permit on the spot. It is totally up to builder/owner to make sure everything is code. I have asked my insp's code questions and I usually get the "If you don't already know why are you doing it " attitude. The only reason he passed your building is because it's "storage" only and not to be inhabited, if they ever come out and inspect for something else and find it being lived in they'll make you change it and prob make you do alot more changes. I think you have legitimate complaints about the insp.

 

[89vert]

I'd fix it by taking the batten strips off and putting drywall right over top of the plywood . That way you accomplish several things .You'll eliminate the waves in your ceiling ,the ceiling will now have a fire rating and you won't have to remove the insulation .

Just my $ .02 worth ...

 

[428]

Not the best choice for a garage but if you sprayed it with texture (popcorn ceiling) that hides a miltitude of sins.
Just make sure all the seams and joints are caulked.

 

[kbs2244]

With a room above, you have a floor that will not let the moisture through.
That is why the plywood is sagging. It is damp.
Exposed insulation in an unfinished attic will let any moisture that comes up perk through it be exhusted through the roof vents. But you have trapped it between the floor and celing. No matter if you take it down or cover it up, you need a moisture barrier on the "warm" side, between the garage and the insulation.
And if leave it as it is, it will just get worse.
All heated rooms generate moisture. But if you do washing or anything that uses water, you need power venting. That is why you have a fan by your shower.

 

[Vicious_Cycle]

I think the sagging is due to the plywood being so thin rather than being affected by moisture. That stuff would sag even without insulation sitting on it if you are on 2' centers.

Several posts on this board have caused me to wonder about the use of plywood for walls and ceilings and the fact that they are not fire rated. I called my insurance agent to ask about this, but he was on vacation. So I asked his rookie sidekick about the use of plywood (which I intend to use in my shop).

He said that the insurance company does not care what I use, but in the event of a fire, they will replace "like for like"... meaning that if my walls burn up with 3/8" plywood on them, the insurance company will pay for 3/8" plywood to replace it, NOT 5/8" drywall. He also said that if it were ATTACHED to my house (it isn't), then I would need to be fire rated.

I'm not sure if it is as simple as he says it is. It seems to me an insurance company will use every excuse they can think of to weasel out of paying a claim.

If anybody doesn't like your saggy ceiling, tell them that you made it that way special for improved accoustics.

 

[logical]

If you were willing to cover the seams I am baffled why you wouldn't have just used 5/8 drywall?

 

[Vicious_Cycle]

If you were willing to cover the seams I am baffled why you wouldn't have just used 5/8 drywall?

I can gue$$.

 

[gcan]

To respond to several of the comments:
1) I contracted the garage all except the interior, my contractor said he
didn't know the ceiling should have been FR sheetrock.
2) The inspector made several stops by the job and two of them were
while the ceiling was being installed...which is why I got so mad when
he said something at the end.
3) I used plywood due to price and the ease of installing plywood versus
sheetrock overhead but now realize the $100 saved and labor were
foolish.
4) I'm not sure what I plan to do over the garage yet but am sure
nobody will live there full time
5) both the garage and upstair room are heated and cooled so where
should the vapor barrier have been installed?
6) the insulation should be able to breath because the upstair room is 12'
and the garage is 26'. Granted insulation is blown in the ceiling cavity
but I would think it would be able to breath out of the ends and vent
into the attic
7) I feel my insurance is okay since it passed the final inspection with out
any documented issues

If I had it to do over I would use sheetrock which is why I made the post so others could learn from my experience

 

[Vicegrip]

All is not lost and your mistake is both understandable and fixable. Install 5/8 drywall over top the plywood. Rent a drywall jack to lift each sheet to the ceiling and hold it in place while you shoot in screws. Mud the seams sparingly and don't sand, shave off the high parts with a 6 inch drywall knife and skin on a second coat. keep doing this until things look smooth. This might take 4 coats or so but each additional coat will take well less time time to instal and dry than the last. Sand with a wet rag balled up and rinsed out from time to time. Put on a coat of paint and go back and mud fix the areas that you can see after painting. The rest does not matter. This will make for passable joint work for a garage. No dust and easy to do.

I would not call my insurance co. for building code advice, call you county inspectors office or look it up in the boca book.
Heat rises. In the event of even a small fire the heat generated will rise and heat the ceiling. When/ if enough heat has built up the gasses at the ceiling flash over and themselves burn. This will ignite the plywood, the wood will burn and the insulation will fall through letting the fire through to burn the structural timbers and on into the upper floors. his is how a relatively small fire in a contained area can burn a ceiling and cause the building to collapse. Garage fires are not uncommon. Hydrated gypsum drywall is very good at stopping heat and fire from getting to and compromising the structure behind it. Use it everywhere you can it might be the difference you need to get out.

 

[gcan]

I agree tht sounds like and most likely is the easiest fix but not as easy as it sounds since my doors, lights, and HVAC unit and vents are installed through the ceiling.
I am going to let my frustrations digest and my body rest from all the work and then I may go back and address the ceiling.

Thanks for the input

 

[kbs2244]

Actually, I used the wrong word when I said "moisture". Moisture is liquid water, and a moisture barrier is was goes under your siding on the cold side of the wall.What I meant to say was "vapor" barrier. Vapor is water that is still a gas, like steam. And a vapor barrier goes on the warm side.

Now, even if the upstairs is heated, you are going to have temp differences, and the vapor will try to get to the cooler side so it can condense. If the upstairs is warmer than the down, you may even have vapor trying to go down, not up.

Before I tore everything apart I would try 2 things. A real thick coat of oil base paint on the garage ceiling. You can buy "vapor barrier" paint if you look hard. Then put some grates in the upstairs floor to let the ceiling breath. Your floor is just too big to let it try and get out at the ends. And think about a dehumidfier up there, drained to the outside.

The problem is where you live. In Al I can believe you may have times when you are using AC downstairs, but not up. This can reverse the traditional idea of the "warm" side being the inside and the "cool" side the outside. This can cause the humidity from the upstairs to come down into the ceiling trying to get to the cool garage.

When you do use the AC upstairs, it will work real well as a dehumidifier.
AC is just a big dehumidifier. That is why the traditional warm and cool side definitions work for a house. The AC just keeps drying out any vapor that infiltrates.

 

[Vicious_Cycle]

I would not call my insurance co. for building code advice, call you county inspectors office or look it up in the boca book.

I assume this was directed at me, since I called my insurance company about using plywood on my walls.

I didn't call them for building code advice. I already know my shop meets code. I called the insurance agent to find out if my policy had any type of exclusion that might prevent them from paying me in the event of a fire, if I have plywood covered walls. This issue is raised here at this website quite frequently. I was told they do not have any such exclusion.

 

[Vicegrip]

Sorry no insult or slight intended. I only meant build to local code rather than what an insurance agent might or might not know. He might be long gone and after tour shop burned down the next guy tells you your not covered due to non code construction. A attached garage under living space is not often code if not fire rated and sealed from fumes getting into the living space. Codes vary all over the US and beyond so it is good to check where you live is all i was intending to mean.

 

[Kong]

The plywood is sagging because of gravity. Also if the building is new construction it has probably settled a bit. Not sure how deep your insulation is but it could also be heavy enough to cause the plywood to sag a little. (think about it, if you blew in x number of pounds of insulation it is all weighing down your plywood and is not supported by the joists. Probably about 1/2 lb. per square foot with a 10 inch fill)

The only real fix other than pulling off the plywood and doing it right, is what others have said - screw a layer of 5/8ths drywall over it.

Your contractor should have mentioned the drywall as an interior finish if he had anything to do with the inside of the garage. Until you actually finished construction the inspector had no real way of knowing that you weren't going to put gyprock over the plywood (should have been obvious when you hung fixtures etc. but they are government workers who get paid to do their job - not go beyond it).

I know a lot of people on this board have a multitude of finishes in their workshops but any exposed finish should be fire-rated.

If the building is not habitated by people, used as a commercial building, or attached to a building that is habitated by people I am not sure that the inspector has anything to say about the fire rating of interior finishes.

As an aside when insulating you should insulate and vapor seal the last barrier to the outside - in your case the roof of the building. Having insulation in the floor like you have is fine if the air circulates through both spaces. It then will act as sound deadening rather than "insulation".

Good luck with whatever you choose to do.

Kong