Who is responsible for ceiling drywall cracks? 1

[gjb2]

I am interested in getting some opinions from other PE's on a deflection/cracking problem on a recently constructed residence. I am the SE of record for a $3 million residence in an area with high snow loads (85psf). The design was mostly performed by a junior structural engineer and reviewed and stamped by me.

There is a 20 ft long ceiling joist span on a 2/12 roof that is framed with with wood I-joists designed with a deflection of L/470 snow load and L/380 total load deflection with SL=85psf and DL=20psf. (IBC limit is L/240 for snow load on roof members). The rafters are perpendicular to the roof slope. There is a glulam beam in the ceiling with points of support (walls below) that cause it to deflect very little. The purpose of the glulam is for perpendicular roof framing for a 4 foot roof overhang. The calculated L/380 deflection of the adjacent I-joists is about 0.63" and a crack has developed in the drywall seam that I believe has been caused by the differential deflection of the I-joist vs. the glulam.

We were contracted by the Architect to perform the structural engineering for this project. The architect has basically told the owner that it isn't his problem. The owner called me and I am going to meet him at the house this week to take a look at the problem.

I am interested in getting others' opinions on this situation. Who do you think should be responsible? Engineer, architect, or contractor? On one hand, maybe I should have required L/1000 deflection...on the other hand that is really not practical or cost effective for most structural designs and this is a situation that I have never encountered before.

On a side note: The owner is an attorney and from the questions he was asking on the phone I felt like I was already on the witness stand. He surely will not go quietly and I can understand...I wouldn't want ceiling cracks in my new home either.

 

[dgkhan]

If I assume that your calculation is right. Than contarctor might not have built it right as work is done unsupervised ( I think). Let him company you on your visit and let him fix it.
If contractor can access from unexposed side let him fill crack with silicone and paint the exposed side again to hide the crack.
I had a situation where this crack keeps coming back. SDo hit the nail on head.

 

[hokie66]

I would not jump to conclusions as to the reason for the crack until you inspect the framing and the crack. As you say the crack is in a drywall seam, it could be due to poor workmanship or lack of a control joint at a stress riser in the ceiling. If it is due to differential deflection, there should be a vertical step, albeit small. But if deflection is the cause of the crack, restricting the deflection of the ceiling joists to .25" may not have prevented what has happened.

In my experience, you are better not to be defensive. Do your best to get to the root of the problem and figure out how to solve it, and the owner should be appeased, even if he is a lawyer.

 

[COEngineeer]

Take some pictures and post it here. It would be very hard to find out what is wrong since you cant see how they frame it.

Never, but never question engineer's judgement

 

[dik]

Your l/380 deflection is something that can be somewhat defended. You might want to check with the American equivalent to the Canadian Gypsum Company? (CGC) Is it possible that the crack has occurred at an area where the adjacent framing is less stiff? and caused by the differential movement between these two elements? Can you post a small sketch of the framing in the area?

The high live load coupled with a lawyer owner could cause some significant hiccups...

Dik

 

[H57]

If the crack was at the joint between the beam and the joists one of the things to consider is the fastening of the drywall at the corner. It is my understanding that drywall should not be fastened right at the end in order to allow for some movement without cracking. I don't know what the guidelines are, but I recall hearing this from a contractor when discussing issues of cracking at a job site.

 

[H57]

I found an article that briefly discusses not attaching drywall close to corners. The term it as floating the corners of the drywall to allow for wood movement without cracking the drywall.

http://www.buildingscienceconsulting.com/resources/walls/dywall_wood_truss_uplift.pdf

 

[msquared48]

I am suspicious from your post that the glulam beam may have created a hard point in the roof framing system, creating a localized differnential deflection problem you describe. If this is the case, then it would have been the structural engineer's responsibility to recognize the situation and adjust the roof framing accordingly.

I am always on the lookout for this scenario and either change the framing or add nore joists in the area of the hard point to minimize the local deflection.

For your sake, I hope I am wrong... I hate lawyers.

Mike McCann
McCann Engineering

 

[csd72]

Try not to point the finger or be confrontational, that is the road to legal issues. The focus should be on fixing the problem not on who is to blame - lawyers are much more expensive than builders or engineers.

Having the builder along on the inspection may be wise, but you should discuss the situation with them first and then ask them not to discuss cause/fault in front of the client.

After the inspection you can then discuss with the builder the best way forward. You will probably find that the builder will not have an issue with supplying a few men for a couple of hours to resolve the issue as long as they recieve guidance from yourself on how to fix it.

Communicate with the client and ensure that you are doing everything you can to resolve the issue. Then keep them appraised as things move on.

As long as the client sees you are working to resolve the issue they will not be considering legal action.

 

[RARWOOD]

Muurphy's 15th Law. Never do work for a client who is a lawyer.

I think you should talk with some of the other architects, who you do work for. To me it is not a structural problem but a finish problem. Although problems in bwith finishes cracking can be due to defelction of the support systems it is usually caused by improper detailing.

I think as long as you follow the deflection guidelines for the structural material you are using you have done your job. All structural elements deflect, glulams will shrink and swell. It should be the architects job to detail the finishes to accomadate movement of the structural system. If the architect specified brick veneer with no control joints and it cracked would it be the structural engineers fault.

One of the problems today, is a lack of experience among younger engineers and architects. There is a lot they are not taught in school and and it seems so many times today, that the additional wisdom of older engineers is not being past done to younger engineers.

 

[csd72]

RARSWC,

The problem is that if there is a court case everyone will get drawn in regardless of if they are obviously at fault or not. Some lawyers use the machine gun method of litigation serving writs at evryone in site hoping that they will hit someone.

Best to resolve the issue before it comes to blame, it is generally much better for everyone.

I agree with the comment regarding experience, experienced engineers are encouraged to go into management, and those who stay behind to do a technical supervisory role are seen as lesser. I disagree with this practice.

 

[MiketheEngineer]

If this is the first winter for this house - then low humidity and natural drying of the wood and drywall may be the problem. IF it is a hair line type crack - then this is most likely the problem.

 

[gjb2]

Thanks for the input. I did find out that the ceiling was completely coated with compound and sanded so it may be just a crack in the coating. I am meeting the contractor and owner there tomorrow to see if we can find a solution. I was not suprised to hear that the achitect won't be able to make it. I'll get some photos and try to post them. How do you post photos here? I do have some framing photos that would make the situation clearer.

 

[MichiganPE]

Based on what you described, it seems to me that the rafters should have been supported on the glulam beam, but I would have to see a framing plan to make that determination. For any residential work I would add a floating drywall detail for all ceilings at interior partitions.