Thread: Calling the experts....

This is an odd one... and one I'm glad I don't have a stake in. A reputable builder that I work with sometimes called me for my opinion.

This is a one year old house and the sheetrock is sagging completely uniformly between the upper floor trusses. It's so consistent it's crazy. The picture doesn't really do it justice but you'll get the idea.

They've had numerous people look at it and nobody has a clue. Of course the framer blames the drywallers, the dryaller blames the framer, etc, etc.

The pieces of info that I notcied that could be relevant:

There's an extremely heavy broquet on the ceiling throughout the house. The only place the sagging isn't occuring is in the two rooms where it's just basic orange peel.

It's the same heavy texture on the main level but given the span of the rooms I'm thinking 16" centers rather than the 24" truss centers for the top level.

The house was basically built during the wet months so there's a chance something got wet (sheetrock, etc).

Because of the uniformity of it I'm not sold on it being a sheetrock problem. Or, at least not one that happended during construction. I suppose the rock could have come from the factory bad. The buyer is convinced that it all sat out in the rain. It would seem that if that were the case it would not be so uniform. Some gets more wet than others, etc.

I'm wondering if the texture could be so heavy that it's just pulling it down. Have you guys ever seen drywall deflect? The builder told me its 1/2" single layer. Everything up top looks fine. The trusses look good, etc.

It's got everyone stumped. The buyer said I was the first one that pointed out the different texture and the lack of a problem with the lighter stuff. I'm kind of just guessing.

The best news in all of this is it's nothing I'm on the hook for.... just more trivial than anything.

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Very weird... must be moisture related.

I saw some wet/damaged sheetrock fall once, its scary, especially when it falls over 40 feet in a commercial building.

I would report that no one should occupy that house due to the high possibility of the fasteners pulling through.

Since this is not a report you are working on, I would still tell the builder the dangers. It looks like time to call an insurance company. Maybe he could tear one sheet down and have the sheetrock supplier come out and take a look first.

Matt,

Could the voids between the rafters be over stuffed with insulation and flooring installed on top causing the sheet rock to bulge instead of sagging?

I would be guessing moisture is the culprit.
Wet season means high humidity when it was delivered, handled, installed. Then add the heavy texture which holds moisture next to the drywall, totally impregnating the drywall and likely sat there for days before it dried out by which time it had already sagged.
Did they use portable propane heaters during construction? That adds lots of moisture to the air.
Did they have any insulation for sound proofing? It so, that could compound the problems.
Bottom line is the only solution is to tear it down and start over.
Was this a 24" span?

Originally Posted by Matt Fellman

The pieces of info that I notcied that could be relevant:

There's an extremely heavy broquet on the ceiling throughout the house. The only place the sagging isn't occuring is in the two rooms where it's just basic orange peel.

Yep, with that much moisture being applied to the gypsum board (during the application of that coating) the moisture softens the gypsum and gravity does the rest.

That's how you bend gypsum around curving walls - you wet it until it is soft enough to be bent around the curve of the studs.

It happened many times in South Florida where the humidity was high enough, for long enough, to allow the gypsum board to deflect over time.

The house we had down there, built in 1975, had a less pronounced effect, but you could see it if you looked closely, and, once you knew it was there, it was easy to see.

The solution is to space the supports closer together. Or add cross supports closer together (which simply accomplishes the same thing - reduces the span of the gypsum board between supports).

It happens because 1/2" board was used instead of 5/8" board, and the support spacing was maintained at 24" o.c.

Give him the attached, read A.2 Application of Water-Based Texture Finishes on Gypsum Panel Product Ceilings, on Page 18.

Read A.2.2.

Yep, Jerry P. nailed it on the head. I just finished working a job/case that had the exact same thing. The repair is to remove all of the drywall ceiling add some supports replace with 1/2" drywall or go with 5/8" drywall.

FYI..... The same thing can happen when cellulose insulation is installed, if care is not taken.

Good information Jerry. Where is that from?

Also,

Technical/topical Papers

As EC Jerry noted getting the rock wet allows it to bend.

I worked a commercial job (inspection side) where they had curved areas overhead. They were using ~ 1/4" rock soaked in water to make the curves. But they at least let it dry out fully. Also was in Colorado where humidity was just a tad lower.

Originally Posted by Jim Luttrall

Good information Jerry. Where is that from?

GA-216

From the Gypsum Association (hence the GA).

GA-216 is the Application and Finishing of Gypsum Panel Products

I posted from GA-216-07 (the newest edition from 2007).

If I read Jerry's attachment right it looks like the sheetrock was installed paralell to the framing instead of perpendicular to framing. This makes sense as to why its bowed the way it is.

FWIW I concur with Scott & Jerry P as I've seen that anomaly in my career as a builder/inspector/consultant.

Wait...

It makes a difference which direction (parallel/perpendicular) the panels are placed? I always installed them perpendicular, but I had no idea that it was required. Guess I should read more.

Plywood, of course, has a strong/weak orientation. How could gypsum have such an orientation?

Originally Posted by Gunnar Alquist

Plywood, of course, has a strong/weak orientation. How could gypsum have such an orientation?

Gunnar,

Think of gypsum board as being a 'stressed skin' product (it is).

The more supports/fasteners (it is really the fasteners, but the fasteners need 'supports' to go into) it is given, the more the stressed skin can resist deformation. Each additional row of fasteners (on additional supports) can hold the stress skin better.

Don't think gypsum board is a 'stressed skin' product? take a sheet and try to break it - not that easy. Now, cut down one side to 'relieve the stress of the skin', try to break it toward the non-cut skin - still hard to break, now try to break it toward the cut skin, it just snaps right down that cut line. All the strength of the gypsum board is from the paper, with the gypsum just holding it apart, thicker gypsum just holds it further apart, making it stronger, just like a thick beam gets stronger (okay, I'm simplifying things here ).

If this is a new house the drywall should have been inspected during construction by the building inspector. When preforming a drywall inspection the inspector should be looking for the proper amount of fasteners and that the drywall is in new condition (not wet and free from visual defects.

being as this is a house that is around 1 year old i would think that it still under warranty if that is the case replace the drywall.

for reasons like this is why drywall inspection is required in most areas

Max Kasten
Building Code Official
Chester PA

Originally Posted by max kasten

If this is a new house the drywall should have been inspected during construction by the building inspector. When preforming a drywall inspection the inspector should be looking for the proper amount of fasteners and that the drywall is in new condition (not wet and free from visual defects.

being as this is a house that is around 1 year old i would think that it still under warranty if that is the case replace the drywall.

for reasons like this is why drywall inspection is required in most areas

Max Kasten
Building Code Official
Chester PA

Max,

I've only seen 'screw inspections', "condition" of the drywall (provided it is not a separation wall or fire wall) is not a concern, just like 'condition' of a Saturnia stone floor is not a concern (unless it created an unsafe walking surface).

Excluding, of course, holes and such in the drywall.

Your description is what a "home inspector" would be looking for, not a "municipal code inspector", at least not anywhere I've seen.

Yes, that does not happen 'overnight', and thus it probably looked flat or reasonably flat at drywall screw inspection, as final, unless it was horrible and indicative of a problem, it would not even be looked at by a code inspector (at least in most areas).

By the way, drywall screw inspections are not even a required inspection in the IRC and most codes, the local Building Official may require them, though.

Jerry

When i preform my inspection on drywall I am looking for fasteners and I'm also looking to see that their are no visual defects in the board. That is where the first line in the code book comes to play "The building official shall have the authority to render interpretations of this code and to adopt policies and procedures in order to clarify the application of its provisions." thats why I'm a building inspector not home inspector

Max Kasten
Building Code Official
Chester PA

Originally Posted by Jerry Peck

Gunnar,

Think of gypsum board as being a 'stressed skin' product (it is).

The more supports/fasteners (it is really the fasteners, but the fasteners need 'supports' to go into) it is given, the more the stressed skin can resist deformation. Each additional row of fasteners (on additional supports) can hold the stress skin better.

Don't think gypsum board is a 'stressed skin' product? take a sheet and try to break it - not that easy. Now, cut down one side to 'relieve the stress of the skin', try to break it toward the non-cut skin - still hard to break, now try to break it toward the cut skin, it just snaps right down that cut line. All the strength of the gypsum board is from the paper, with the gypsum just holding it apart, thicker gypsum just holds it further apart, making it stronger, just like a thick beam gets stronger (okay, I'm simplifying things here ).

Jerry,

I guess it must be Friday, because I don't get it. I understand the "stressed skin" part. that is reasonable, but I don't get the orientation. Roughly the same number of fasteners would be used, but on fewer members. It should (I would think) provide the same support. I can understand the thickness being an issue. Stressed skin or plywood, it will sag less if it is thicker because the outer skins are farther apart.

Originally Posted by Gunnar Alquist

I understand the "stressed skin" part. that is reasonable, but I don't get the orientation. Roughly the same number of fasteners would be used, but on fewer members.

More support members, more fasteners.

Think of it this way:

Go way back to when you were a kid, or, more recently to when you had (have?) young kids.

Remember that sheet pulled over the backs of chairs to make a tent and play under?

Drape that sheet over to chairs and try to hold it tight, it will droop unless a lot of weight is applied to each end where it lays on the chair seats.

Now, bring in some sawhorses and prop the sheet up, it still droops a lot between the saw horses and between the saw horses and the chairs.

Now pull it tight over the first saw horse (starting at either end), then place some books on the saw horse where the sheet lays on it to hold it tight on the saw horse. Now pull the sheet tight over the next saw horse, adding some books on that saw horse. Finally, pull all the slack out of the sheet over the other chair, placing more books on the chair seat to hold the sheet in place.

Now, the sheet is nice and straight and tight.

More fasteners holding more of the skin in more places to more supports.



Now get a broom and let's ride our horses.

Hmmm. Well, OK. I will have to take your word for it. That is until I can do a "Mythbusters" test for myself. Maybe I can talk them into doing it for me. It's only a 70 mile drive down to South San Francisco.

Hi,

I think it's simply the half inch rock. Abouit 98% of the ceiling "joists" in new construction here are simply the 2 by 4 bottom chords of roof trusses placed 2-ft on center with nothing else. As you know, Seattle's climate has a reputation for being damp, and I've never seen that except on DIY jobs where 1/2 inch rock was used.

ONE TEAM - ONE FIGHT!!!!

Mike

Also happens with 5/8" green board in areas that aren't climate controlled. This is a sencond floor common hall in an older apartment building. There is an open breezeway entrance at both the front and back of this building. Material was verified by the attic/roof hatch in the background.

Telegraphing also occurring at the walls.

Obviously glossier paint finishes only exacerbate these problems.

Originally Posted by BARRY ADAIR

Also happens with 5/8" green board in areas that aren't climate controlled.

"green board"

Here's likely why:

From the 2006 IRC. (underlining is mine)

- R702.3.8 Water-resistant gypsum backing board.

Gypsum board used as the base or backer for adhesive application of ceramic tile or other required nonabsorbent finish material shall conform to ASTM C 630 or C 1178. Use of water-resistant gypsum backing board shall be permitted on ceilings where framing spacing does not exceed 12 inches (305 mm) on center for 1/2-inch-thick (13 mm) or 16 inches (406 mm) for 5/8-inch-thick (16 mm) gypsum board. Water-resistant gypsum board shall not be installed over a vapor retarder in a shower or tub compartment. Cut or exposed edges, including those at wall intersections, shall be sealed as recommended by the manufacturer.