# Drywall sagging on 24" o.c.



## ECinc (Jun 10, 2006)

...


----------



## Rouerplastering (Sep 6, 2010)

I have had this problem also with spray foam insulation. Only one time though. The problem was the board was hung before the insulation properly cured and sucked the board in. Definately talk to your insulator and he should be able to tell you the proper time frame for covering it up.
P.S. I would never hand anything but 5/8" on ceilings. Especially 24 o.c. The high strength 1/2" does pass most codes but I have worked with both and would never trust the 1/2". Just my opinion though. For the $50 difference in price the 5/8 is well worth it.


----------



## Sir Mixalot (Jan 6, 2008)

Was the drywall hung perpendicular or parallel to the truss's?


----------



## Rouerplastering (Sep 6, 2010)

Sir Mixalot said:


> Was the drywall hung perpendicular or parallel to the truss's?


 What psycho would hang the board parallel?


----------



## ECinc (Jun 10, 2006)

Rouerplastering said:


> I have had this problem also with spray foam insulation. Only one time though. The problem was the board was hung before the insulation properly cured and sucked the board in. Definately talk to your insulator and he should be able to tell you the proper time frame for covering it up.
> P.S. I would never hand anything but 5/8" on ceilings. Especially 24 o.c. The high strength 1/2" does pass most codes but I have worked with both and would never trust the 1/2". Just my opinion though. For the $50 difference in price the 5/8 is well worth it.



In this case the board was hung and then the foam was sprayed down onto the backside of the drywall from inside the attic.


----------



## ECinc (Jun 10, 2006)

Sir Mixalot said:


> Was the drywall hung perpendicular or parallel to the truss's?


perpendicular


----------



## Rouerplastering (Sep 6, 2010)

ECinc said:


> In this case the board was hung and then the foam was sprayed down onto the backside of the drywall from inside the attic.


 It's obviously an insulation problem that the insulators should have known not to do if they are professionals. If your looking for who's responsible for the problem, I would start there. Unless they were instructed by you to do it that way but even still, if a contractor or HO asks me to do something that is going to ruin another aspect of the job, I would feel ultimately responsible since it is my trade, and by negelct or ignorance I didn't warn you and refuse. 

Now if your trying to figure out how to fix it, there is no cheap fix.
The best fix, IMO, is to hang another layer of rock over the top and refinish it. Or, if your finisher is skilled enough he could fill all the concaves in with mud and repaint. Either way it sounds like a mess. But in no way is your finisher responsible.


----------



## ECinc (Jun 10, 2006)

This is a system we have used many times before, my own house included. Never had this happen.


----------



## Cletus (Jan 7, 2008)

Rouerplastering said:


> I have had this problem also with spray foam insulation. Only one time though. The problem was the board was hung before the insulation properly cured and sucked the board in. Definately talk to your insulator and he should be able to tell you the proper time frame for covering it up.
> P.S. I would never hand anything but 5/8" on ceilings. Especially 24 o.c. The high strength 1/2" does pass most codes but I have worked with both and would never trust the 1/2". Just my opinion though. For the $50 difference in price the 5/8 is well worth it.


I'm curious what it is you are writing about in this post.

What was the foam sprayed onto if the ceiling drywall wasn't there? If the foam wasn't applied directly to the drywall how would it attach itself and "suck" the board in?


----------



## Sir Mixalot (Jan 6, 2008)

Rouerplastering said:


> What psycho would hang the board parallel?


You would be surprised how many posters that come on here, didn't know that was a big no no. :w00t:
So, the question was intended to figure out the OP problem from the begining.


----------



## Rouerplastering (Sep 6, 2010)

Yeah, there's something to it though because it has happened to both of us. Even if it happens 1 out of 10 times or even 50, that's too often. And there's a reason. On the house I plastered it happened on the gable ends of one room.And it sucked the board in a good 1/2" in spots. It cracked and broke the board in those areas. Would a vapor barrier help? I don't know I'm just a plasterer. If visquin is put up before the wallboard then the shrinkage of the insulation wouldn't be attached to the back of the board. If you did have a vapor barrier, then I'm stumped.


----------



## Rouerplastering (Sep 6, 2010)

Cletus said:


> I'm curious what it is you are writing about in this post.
> 
> What was the foam sprayed onto if the ceiling drywall wasn't there? If the foam wasn't applied directly to the drywall how would it attach itself and "suck" the board in?


The time it happened to me it was sprayed on exterior walls. I should get a big "duh" for not taking into account the board has to be up to spray the ceilings.


----------



## Cletus (Jan 7, 2008)

ECinc said:


> This is a system we have used many times before, my own house included. Never had this happen.
> 
> I just can't understand why it happened this time, and with two completely different companies doing the spraying?


I have seen this before and had heard various answers as to why. One was that the foam was sprayed too thick on the first pass and the contraction as the foam cooled pulled up the ceiling. Another was that condensation formed at the VB created by the foam, wetting the top of drywall, and causing upward expansion.

Fortunately I wasn't the one paying to fix it and never heard what the true cause may have been.


----------



## Morning Wood (Jan 12, 2008)

No strapping on the underside of the trusses? sounds like some planets lined up just right and it caused this. Seems like the most reasonable explanation is that when the foam was curing it pulled the drywall up. you would think that this would have been noticeable within a couple weeks, not a year. You don't have any moisture issues in the attic do you? Quickest fix would be to hang 3/8" board over the 1/2" and remud, paint. Maybe in the future you should put rosin paper or felt down on top of the drywall but still allow the foam to do its air sealing process.


----------



## Big Shoe (Jun 16, 2008)

Morning Wood said:


> No strapping on the underside of the trusses? sounds like some planets lined up just right and it caused this. Seems like the most reasonable explanation is that when the foam was curing it pulled the drywall up. you would think that this would have been noticeable within a couple weeks, not a year. You don't have any moisture issues in the attic do you? Quickest fix would be to hang 3/8" board over the 1/2" and remud, paint. Maybe in the future you should put rosin paper or felt down on top of the drywall but still allow the foam to do its air sealing process.


 
When doubling ceilings I never go less than 1/2''. Especially when trusses are 24'' o.c. It may sag.

as far as the OP....Not familiar with that system,responses seem to make some sense. Good luck.


----------



## MAD Renovations (Nov 18, 2007)

Was there poly installed between the drywall and the trusses? This is a must for code here.


----------



## parkers5150 (Dec 5, 2008)

i would be of the opinion that the moisture from the foam on only one sie of the drywall caused it to buckle. that being said, since a few people have seen this on a few diff occasions i think the one variable you could be overlooking is weather conditions during install as related to the moisture prob and dry times. I am also of the camp that would never go less than 5/8" on the lid w/ 24" oc


----------



## Framer53 (Feb 23, 2008)

Tattoo said:


> Was there poly installed between the drywall and the trusses? This is a must for code here.



Actually then you would have two vapor barriers. Remember he used closed cell foam, no need for vapor barrier.


----------



## greg24k (May 19, 2007)

It could also sag from water-based texture applied to the face of it or it could also sag from insulation...especially if damp conditions are present.

In addition when buying sheetrock at Box stores, you have more chances to have problems with it. 

Now USG is using new 1/2" sag-free sheetrock, which is designed for 24" applications and it can be installed in any direction. I just seen the guys use this sheetrock in a restaurant my friend is building, it was called for that type on the plan schedule.


----------



## MAD Renovations (Nov 18, 2007)

Framer53 said:


> Actually then you would have two vapor barriers. Remember he used closed cell foam, no need for vapor barrier.


 
True but wouldn't the poly have stopped the spray foam from sticking to the drywall?


----------



## Tim0282 (Dec 11, 2007)

I don't like plastic on the ceilings. But I would like it here, to keep the moisture from the foam getting in the drywall. The foam, when sprayed on comes out of the machine at something like 120 degrees. That puts a lot of stress on the finished drywall. That is a huge temperature swing. 
About the 5/8ths rock compared to the 1/2 sag resistant. I cut a 24" square piece of each and put them on two 2x4's each and stood on both. The 5/8ths went right to the ground, the 1/2 didn't. I have used Sag Resistant since 1993 (when it was introduced) and have had no issues with it. Always use 5/8ths in garages and all commercial. (to meet codes)


----------

