Drywall Cracking 1

[hawkaz]

Does anyone have literature on causes of drywall cracking at exterior steel stud walls?

I have a building that was designed 5 years ago; they have over 180 minor drywall cracks throughout the structure. The stud deflection under max. wind load for the area is h/400. Most (but not all) cracks occur at window corners and stairstep up following the drywall joints. Most of the cracks are on the exterior walls. Some even occur in drywall that was installed on top of plywood shear walls.

No cracking is noted in the stucco on the opposite side, no cracking is seen in the stem walls. Cracks have been patched numerous times, but keep re-occurring. Expansion joints have been installed during the on-going repair process.

The owner, architect... are frustrated that the repairs aren't holding, and they insist the cracking must be due to stud movement. Since the stucco isn't cracking, I am having a tough time agreeing with this. I suspect sub-standard workmanship and poor patches, but can't back it up.

Any help in finding causes for this type of cracking would be appreciated.

 

[a2mfk]

Well, all drywall cracks, that is for sure. I look at interior distress all the time doing forensic investigations. I can lend you a hand off the board. Curious though that there is no stucco cracking, but that tells me it is not likely related to structural movements or differential settlement.

Regards,
Andrew Kester, PE
Florida

akester74@ "google" mail.com

 

[dik]

Can you post a photo of the cracking condition? Our office has a series of horizontal cracks above the door frames/window frames. There is a large area of drywall above. The cracks have been repaired 3 times now and have since cracked. The proper solution is to introduce a joint using 'J' molding, but no one seems to want to do this.

Dik

 

[Ron]

Most drywall cracks result from drying shrinkage. It is common for those to manifest at corners and at re-entrant corner conditions like windows and doors. The usual manifestation at windows and doors is a diagonal crack off the corner.

Look more closely at the stucco. It is sometimes difficult to find stucco cracks, particularly if an elastomeric coating was placed on it. There are likely cracks there. They too, are caused by drying shrinkage and, fairly often, improper lath placement.

I doubt the cracks in the drywall are from structural movement. If that were occurring, you would see cracks at midwall or other areas not associated with drying shrinkage.
In short, the studs probably have nothing to do with it.

What is the use of the building? Is there any chance that the use of the building creates humidity spikes? Is the HVAC system dehumidifying too much?

 

[beton1]

When drywall is applied, joints should be staggered. At windows and doors etc., it is good practice to maximize full sheets. In fact sheets are cut strategically so that there are no seams in line with the edges of opening. Sheets should also be run horizontally (not 'stand-up') especially for exterior walls (much like plywood on walls/floors). It may be that a lot of cut sheets were used and therefore a lot of joints. Having worked summers with my cousin in the dryawll trade, I picked up a lot of the little details.

 

[a2mfk]

I agree with Ron. And in my experience, when drywall cracks from structural movements, at least structural movements that you should be concerned with, it does so in the form of cracks through the actual gypsum board. Often this is in the form of diagonal cracks at window openings, and the crack width will vary along one crack. Like Ron and others said, cracks along joints are likely the result of workmanship and materials issues. These are the weakest parts of the assemblies. If you have a less dimensionally stable wall system such as wood framing, then you could throw that in there as an additional contributing factor.

 

[amecENG]

I also agree with Ron. I have seen this a few times before and have attributed it to changes in humidity in the interior space.

 

[BAretired]

Temperature movements could be a factor if the steel studs are not properly insulated. That seems to be the main difference between an inside and outside wall.

BA

 

[TXStructural]

1) check the wall interior for moisture, mold, rust, etc. and treat accordingly. Be sure the track at the base isn't rusted - very common in poorly waterproofed exterior walls.
2) check that slab movement relative to the wall isn't an issue (where the slab is not integral to whatever supports the studs.)
3) fix the cracks at corners of the windows and doors using zinc expansion joints - they are very thin and allow seasonal movement without cracks appearing - I just did this to my entire 40 year old house, and it is common practice with commercial buildings in areas with expansive soils.

 

[concretemasonry]

One thing about steel studs is the extreme thermal short circuiting due to the heat loss. This can cause stress variations and stresses that are not structural but can combine with structural stresses due to deflection and cause surface wall conditions that could cause cracking of thin (<1") veneers. The high relative deflection of steel studs compared to other materials could magnify problems.

Just a thought based on general properties.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[southard2]

I had a building where there were numourous cracks in the drywall. It was tilt-wall. What got us off the hook was that it was a proto-type and the other two school were completely free of defect. I believe it was happening on all kinds of walls.

The architect on the project attributed it to lack of joints and humidity because I think the mechancial systems took an extra long time to get into place. Plus it is Florida where things are really muggy to begin with.

I had another project once where the dry wall on a stud wall directing under a floor beam near an expansion joint cracked. I attributed this to the fact that the beam was moving horizontally and the cold-formed steel studs and track were ridgidly connected to the beam. Here we got of because our specs called for slip tracks when mounting to the bottom of a beam. The problem was solved apparently by not detaching the tracks but by using closer joint spacing for the repair.

John Southard, M.S., P.E.

http://www.pdhlibrary.com

 

[hawkaz]

Thanks for all the replys. I have tried finding some pictures that show the cracking, but these cracks don't show up well.

For more information: this is two single story office buildings. I am trying to get information on the weather when this was originally installed so we can see if there were any extreame weather issues at the time.

They brought in a new drywall repair guy last week. He patched one section- and by the next morning, it was cracked again. No wind that night and the temp differential was only 30 degrees. Doesn't seem like enough to cause this cracking.

I will follow up with some of the other suggestions.

Thanks