| Author |
Message |
Russ Hinkle, AIA, CDT, LEED BD+C
Senior Member
Username: rhinkle
Post Number: 131
Registered: 02-2006
| | Posted on Friday, February 13, 2015 - 07:52 am: |    |
Our typical details call out for control joints in the drywall spaced out maximum of 30’ and from the top corner of headers and door frames. We also include a detail for a control joint in a rated wall that is two studs with mineral wool in between at the joint.
We have interior metal stud bearing walls with precast plank. The rated control joint is just about impossible to do in the structural bearing wall. Too many studs at the heads and too much strapping, etc. in the middle. Owner still wants control joints in the drywall, but we cannot provide them without compromising the rating.
In our opinion this wall (the metal studs) is not going to move. The gypsum is well attached to the stud wall, will the gyp board need relief? We are thinking the control joints are not needed but we do not have any experience with this.
What is your experience (if any)? Thoughts?
Russ Hinkle |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 834
Registered: 01-2003
| | Posted on Friday, February 13, 2015 - 08:40 am: | |
Use an additional layer of gypboard. The first layer maintains the rating, the second can have all the control joints you want. |
Nathan Woods, CSI, CCCA, LEED AP
Senior Member
Username: nwoods
Post Number: 629
Registered: 08-2005
| | Posted on Friday, February 13, 2015 - 11:55 am: | |
Agreed. This is how we do it too. |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 835
Registered: 01-2003
| | Posted on Friday, February 13, 2015 - 01:47 pm: | |
Don't do this. http://swspecificthoughts.blogspot.com/2014/10/just-another-day-drywall-reveal.html |
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 706
Registered: 10-2007
| | Posted on Friday, February 13, 2015 - 02:05 pm: | |
I assume the metal studs are on top of the precast plank not supporting precast planks.
Do not touch the structural bearing wall without checking with the structural engineer on the project.
From an engineers perspective I have found two types of problems related to joints. The first is not providing joints where there will be real movement. The second is an obsession regarding control joints where experience indicates there is no real need.
I suspect this may fall into the second category. What type of movement will these joints accommodate? |
Guest (Unregistered Guest)
Unregistered guest
| | Posted on Friday, February 13, 2015 - 02:13 pm: | |
Control joints are important if you don't want cracks. Even if you think the studs won't move, the materials will expand and contract with changes in temperature and moisture.
Talk to your local reps. A lot of manufacturer's have details of control joints that have been tested that might work for your situation. Then you don't have to put an extra layer of gypsum on the wall.
Although, if the Owner wants to pay for gypsum that isn't necessary ... |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 836
Registered: 01-2003
| | Posted on Friday, February 13, 2015 - 11:14 pm: | |
Gypboard is cheap. |
Russ Hinkle, AIA, CDT, LEED BD+C
Senior Member
Username: rhinkle
Post Number: 132
Registered: 02-2006
| | Posted on Sunday, February 15, 2015 - 10:40 am: | |
Yes, the planks are bearing on the metal studs. Not a typical construction method for us. We are not finding any details for this condition from reps or contractors.
I am beginning to think that the second layer of gyp is a good solution.
Russ Hinkle |
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 707
Registered: 10-2007
| | Posted on Sunday, February 15, 2015 - 01:29 pm: | |
Precast planks on metal studs are not a typical construction system. Because of this and what it implies involve your structural engineer in this discussion so you do not undo what your SE is trying to do.
I am not convinced that you will have problems with cracks if you do not have these joints. I hear this is common belief but some times individuals do things without really understanding the logic. I believe you will likely be able to find installations where the joints were not provided and where there were no problems with cracks.
It is not clear to me how the extra layer of gyp prevents cracks. |
Russ Hinkle, AIA, CDT, LEED BD+C
Senior Member
Username: rhinkle
Post Number: 133
Registered: 02-2006
| | Posted on Sunday, February 15, 2015 - 02:13 pm: | |
Mark - agree with you. Our structural engineer is involved. He does not want to comment on gyp bd cracking and we will not change the metal stud system that was designed. I am with you in that I don't think there will be an issue. I don't remember seeing joints in hotel walls (similar construction system). Trying to convince the owner that it will not be an issue.
Russ Hinkle |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 837
Registered: 01-2003
| | Posted on Sunday, February 15, 2015 - 04:02 pm: | |
Mark, the extra layer of gypboard allows the use of as many control joints as you want.
Russ, are you citing GA-216? GA-216 requires the architect to show control joint locations, and requires them at intervals of 30 feet. Will the gypboard crack? You won't know until it does. Will the owner care? You won't know until it cracks.
In general, it's good to follow recommendations of GA, BIA, and other industry associations. Cracked drywall (which is common) may not be a life safety issue, but ignoring these recommendations can put you in an awkward position.
Attorney: Are you aware of this industry standard? (Hard to deny if it's cited in the specifications.)
Architect: Yes.
Attorney: And you chose to ignore it.
Architect: Yes.
It's all downhill from there. Perhaps the owner will decide you should pay to fix the problem, which this attorney will be glad to show is the result of your decision. |
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 708
Registered: 10-2007
| | Posted on Sunday, February 15, 2015 - 07:34 pm: | |
Sheldon
I have seen this all before a standard based on a questionable premise that individuals feel compelled to follow because of fear of criticism. A first step is to involve the client and explain the implications of following this approach. Show pictures of installations without joints. At this point You can tell the attorney you had discussed the issue with the client and he had accepted the risk. |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 838
Registered: 01-2003
| | Posted on Monday, February 16, 2015 - 12:37 am: | |
No question, that is an excellent approach. For the project in question, the owner may well decide that some amount of drywall cracking is acceptable.
However, an owner may not understand the implications no matter how well you explain them. As you note, you can show the attorney the problem had been explained and discussed, but if you end up dealing with an attorney, you lose even if you win. If you do end up in that situation, I suspect it will be hard to convince an owner or a court that your opinion of what's a questionable premise is worth more than the opinion of a recognized industry organization.
More to the point, it seems architects too often either don't understand potential problems themselves, or don't think there will be a problem. |
Dave Metzger
Senior Member
Username: davemetzger
Post Number: 559
Registered: 07-2001
| | Posted on Monday, February 16, 2015 - 10:13 am: | |
I don't understand why there is a question on this issue. The purpose of control joints in this case is not to prevent drywall cracking from movement of the substrate (ie the load-bearing metal studs) because as been noted there is unlikely to be such movement--it is to control drywall cracking due to changes in temperature and humidity.
From National Gypsum: "Gypsum wallboard, as well as other building products and materials, is subject to some form of movement induced by changes in moisture, temperature or both. To relieve the stresses that occur as a result of such movement, control joints are required in both partitions and ceilings. Control joints are frequently necessary to prevent cracking in gypsum wallboard. Cracking may also be caused by stresses resulting from building movement."
In Russ' case, there is unlikely to be stresses resulting from movement of the substrate. And within a hotel room, the expanse of gypsum board is not likely to require control joints (ie likely less than 30 feet). But in hotel corridors--yes, I'd sure recommend the use of control joints. Whether the drywall is on load-bearing studs, non-load-bearing studs, or hat channels on masonry or concrete, there will be expansion/contraction of the drywall due to changes in temperature and humidity.
The owner has said this is a concern for him. There is an easy way to accommodate this, as Sheldon has noted--an extra layer of gypsum board. If the owner wants it and is willing to pay for it, and it's consistent with recognized industry practice and the standard of care, why is there a question? |
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick
Post Number: 1616
Registered: 03-2002
| | Posted on Monday, February 16, 2015 - 02:51 pm: | |
And as an added benefit, the owner will get a better performing wall acoustically. |
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 710
Registered: 10-2007
| | Posted on Monday, February 16, 2015 - 10:01 pm: | |
Control joints are only effective if the two sides are allowed to move freely. So if the joint is spanned by other layers of gyp or other materials the movement cannot happen at the joint. Thus if the movement is real the resulting cracking will likely occur at some other location.
It is easy to get the Owner to say that he is concerned about cracking. Do you similarly ask is he concerned about all of the other possible things that could go wrong?
In a related situation look at an exposed concrete slab and not the cracks. The cracks do not always align with crack control joints yet nobody is normally bothered by the cracks unless somebody starts looking for the cracks. |
Guest (Unregistered Guest)
Unregistered guest
| | Posted on Tuesday, February 17, 2015 - 05:43 pm: | |
"Gypboard [sic] is cheap."
It may be cheap, but it isn't free. Nor is the labor needed to install it free. Depending on how much area you are talking about, it may be more expensive than you think. Other options may be cheaper than the cheap "gypboard" [sic].
Some information here for control joints including detail in fire-rated wall: http://nationalgypsum.com/resources/tech-talk-controljoint.htm
You could also use something like this: http://www.cemcosteel.com/steel-framing/head-wall/fas-track-1000-and-dda/fas-093x-fire-rated-control-joint |
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