Thermal Bridging on Brick Building
We are building restaurant in North Carolina and have run into a big issue. The plans describe, from inside to outside—metal studs, OSB, vapor barrier, continuous foam board, air gap, brick. Well the contractor forgot to put the foam board in and the brick has already gone up. We now have a thermal bridge from inside to out and the owner and architect will not have it. We are looking for a way to remedy this issue without tearing down all the brick and losing 3 weeks and tens of thousands of dollars. Any suggestions on solution? I have attached photos. Pls feel free to email [email protected]. We can pay a feefor the time but need an answer asap.
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I do not see any possible fix short of removing the brick.
What was built is not code compliant cant be made code compliant if this slips past the inspectors the building would likely become a mold factory as the steel studs will conduct the cold from the exterior to the interior where it will be below the dew point wetting the drywall to the point where mold can grow in the wall if not on the surface.
Walta
Agreed, but what about 1-2" of polyiso or rigid foam inside of the metal studs (between studs and drywall), and then ensuring this continuity so that the studs are now basically the same temp as the outdoors and there is no cold condensing surface. Thoughts>
Interior side insulation could be an option, there's a GBA article about it here https://www.greenbuildingadvisor.com/article/walls-with-interior-rigid-foam You'd be introducing tons of new complications that have to be considered and incur the associated delays in getting this figured out and signed off by the Architect, Client, and AHJ. Not to mention the client will be losing interior space (however negligible) which may be a non-starter.
I'm assuming that somehow the liability for this is in your lap, otherwise it would be a no-brainer to have the contractor rip it all down and do things properly on their own dime.
Good luck!
Iron Pine,
Are you the brick contractor? If so, you are liable.
If you are the owner, the cost of the error must be borne by the brick contractor or the brick contractor's insurance company.
If the Architect has a wall assembly designed with rigid foam and the General Contractor, or whoever pulled the permit, didn't make sure the plans were followed through, in most municipalities I work, that person or entity is responsible. Depending on the type of contract, the Architect maybe liable as well.
I would consult with a Construction Defects Attorney, as I don't think there is a simple fix, unless you tear down all the brick and rebuild. I would not accept anything else. You are asking for lots of possible problems for years to come.
Martin is spot on here. The general rule goes like this:
"If it's designed right, and the contractor built it wrong, the contractor is liable. If it's designed wrong, and the contractor built it as designed, the designer is liable".
If your architect designed it correctly, and the correct drawings were provided to the contractors, the contractors are responsible REGARDLESS OF THE COST TO THEM TO FIX IT. If you have a GC, the GC should fight this battle for you with their subcontractor. Your architect may be able to help too. Last option is legal work, which isn't ideal but might be your only option. If you required a bond from your contractor, contact the company that bonded the contractor/project. This is why I require contractors to name my company as "additionally insured" on their policies prior to start of work too -- it makes it possible for me to go to their insurer directly and bypass the contractor.
DO NOT PAY THAT CONTRACTOR UNTIL THEY FIX THIS!
Insulating on the interior could be an issue with any services that need to be installed in those walls. Things like water lines must be inside the insulation to avoid freezing.
I agree with Walter here that you don't really have any options aside from replacing the brick. The only thing I could think of would be removing the studwall, insulating properly, then rebuilding the studwall, but that may or may not be possible on your particular project, and it might also reduce the useable square footage of the building. I'd go after the contractor who made the mistake myself, and it should be very easy to prove if you have drawings showing something other than what was actually built.
Bill
Since it is a restaurant and I'm looking at CFS wall, I'm assuming it needs to be a UL assembly. This means you can't randomly add to it, if it is not listed, it can't be built. Even if you do change the assembly to another UL assembly, it would have to go back to the city for approval which would probably take longer than to re-build.
About the only solution that would work in terms with similar center of cavity R value is spray foam between the studs. Because of the thermal bridging of the studs, the assembly R value (~R8 with closed cell spray foam) would still be much less than the original plan called for (R13 assembly with R4.5 rigid). Not sure if the costumer or the city would accept that.
Thank you all for the help, this blog is such an amazing resource. I am not liable nor was I responsible for the construction. A friend is the GC and reached out in desperation hoping to figure out a way to make things right. An insulation pro and self proclaimed building science geek think that spray foam between the studs and 1" of foam between drywall and studs could solve the problem, but I agree that it's taking on too much risk.
Spray foam between metal studs doesn't gain you as much as you might think due to the thermal briding of the studs. It's less of an issue with wood studs, but still a concern. 1" of foam on the interior side of the studs behind the drywall will complicate all the mechanicals (electrical boxes, etc.), and bring up some additional risks for the wall assembly.
The only reason I'd be inclined to try to change things around and get'er done here would be if I was on a tight schedule. It is far preferable to fix it "right" and go after the mason, or whichever contractor was responsible for building it incorrectly in the first place. There is no reason you should have to suffer with bandaids on a botched job just because someone didn't follow the design on the print. You may find you have issues at inspection time too -- energy codes are being enforced more stringently these days, so the city might also frown on any bandaids here.
Bill
Seems to me the idea of filling the code required air gap between the masonry veneer and the sheeting is a nonstarter because while masonry look water proof it is not at all water proof and is a reservoir. When the surface gets wet the masonry soak up the water. This water will often run down the interior surface and exit out the bottom weep holes. If you fill that gap water would cross the gap coming in contact with the sheeting and find its way into the wall leading to mold and rot.
The one inch gap would get you up to maybe R7 at best well below your code requirement I would assume.
Walta
It looks like this could be an option - https://www.echotape.com/products/fo-v2344-2348-single-sided-thermal-break-tape/
This would add 1/4-1/2" of material to the assembly, but we could then possibly reduce the OSB or drywall thickness to account. In looking through some GBA articles, it appears that this small of a thermal break is not preferred, but it looks to be a large step-up from no break. My guess is it will add about 0.2-0.4 to the wall U value, any thoughts?
By the way, the reason can't be held accountable on this job as there were other mishaps along the way. 4" of spray foam with this produce will probably keep us above R15-R20. @Walter Ahlgrim, filling in the air gap between teh brick and vapor barrier was never considered, we understand the importance of this!
Be careful with reducing the thickness of the cladding, it may have been specced for fire resistance.
I would say a quarter inch of closed cell foam might have an r-value of 1.5 or U-0.67. Four inches of spray foam might give R-24 or U-.04. Let's round down the steel framing to R-0 and assume a framing fraction of 15%.
So the U-value of the wall assembly is 0.15* 0.67 + 0.85*.04= 0.1+ 0.034=0.134 which is equivalent to R 7.5.
OK, let's look at it another way. Let's say you need to get R-15. Which means a U 0f 0.067. The spray foam gives 0.034, so the framing can't give more than .033. It's 15% so the U-value can't be over 0.22, which means the r-value can't be below 4.5. That's about 3/4" of closed cell.
Another way to do it would be to build a non-attached wall on the inside with the studs offset, then spray foam the whole assembly.
As others have pointed out, if this is a fire-rated assembly you need to have the architect review and possibly submit it for re-approval.
The wall is 2x6, so it would be 5.5" of foam. Additionally, the cross section (see image attached) would allow for some foam to sit in this space. Therefore, I think a framing fraction of 15% is too aggressive.
Foam = 5.5"xR7.5 = R41
Studs - not sure how to factor this in as the foam between the two faces of the metal studs have foam---I would think you just take a % of the wall R value away to account for the thermal bridging. I recall a wood framed wall to reduce R value by about 30%--metal is definitely a worse culprit but there is less material and you have the small amount of foam on the face. Even at a 50% reduction, we are close to an R20. Would you agree on any of this?
I don't agree at all.
When you have parallel heat paths you have to use U-values like I did in post #12.
Steel has an R-value of about 0.003 per inch, which rounds down to zero. A steel stud has a c-shaped cross section where it has a 1-5 inch face on the exterior, a 1.5 inch face on the interior, and steel connecting them. For practical purposes the r-value is the same as a solid piece of steel 1.5 inches thick. Putting foam inside the "C" does absolutely nothing to change the heat transmission characteristics of the wall. My 15% framing fraction estimate comes from looking at it this way.
The longest path from one side of the stud to the other is the width of the stud plus twice the thickness -- 5.5 plus twice 1.5, or 8.5". At 0.003 R per inch that gives an R-value of 0.0255 from one side to the other. Closer to the edge of the stud is less. I used zero for the steel in my calculations in #12, but put in 0.0255 and you'll see the answer doesn't change.
Are those 2x6 studs structural? If they're not, you'd be better off taking them out and replacing them with two rows of 2x4 that are offset.
DC,
As Joe Lstburek said "Put an R-19 batt in a steel stud wall and you are lucky to get R-5 to R-6 in the real world. That’s equal thermal resistance wise to about 1 inch of rigid insulation installed on the outside of the steel studs."
https://www.buildingscience.com/documents/insights/bsi-005-a-bridge-too-far
DC Contrarian is correct. Thermal bridging in a steel stud assembly is a big problem.
Doesn't matter what you insulate with, you can't really get much above an R8 or so assembly, doesn't matter the stud deapth.
The thicker you go, the worse the assembly R value loss is. For example a 10" CFS wall with R38 batts has an assembly R value of R9. So all that insulation is pretty much wasted.
You can look at some of the assembly R values in Table 1 here:
https://ncma.org/resource/thermal-bridges-in-wall-construction/
Keep in mind that even there, R1.5 comes from the brick and air gap.
When it comes to steel walls, cheapest insulation in the cavity (since it doesn't matter much) and you want most of the insulation on the outside.
The 1/4" or 1/2" of tape helps a bit but won't do all that much. Plus if it is a load bearing UL assembly, you can't use it.
Upon reflection, I'm going to change my answer and say that a 2x4 wall with 2" of foam on one side is better than staggered 2x4's in a 2x6 wall.
Deleted
When you're wrong you're wrong. Thank you all, I will take this to the builder. If tearing out the brick is off the table, I am going to advocate, in order:
1. Replace steel with 2x4's and 2" of rigid foam.
2. Figure out a way to add 2" of rigid foam to the interior wall
3. use blow in insulation and tape, but know the R value closer to 9, which the architects and engineer will have to sign off on.
4. Reconsider your decisions, remove the damn brick, do it right, and improve systems that allowed for someone to sign off on the sub's shop drawings.
I want to say thank you again, this is has been very educational. Especially @DCContrarian!
TIm
@ironpinecapital: All of us who are developers, builders, contractors or subs have probably been in this situation - a whole bunch of seemingly small errors that converge to create a huge issue.
I'm posting to strongly urge you to consider just tearing it out and doing it properly. Even though that seems like an insurmountable economic or scheduling obstacle at this point, my experience is that you will later wish you had done this. This issue will continue to dog you for a LONG time. Even if, by some chance, you get the owner/architect/code official to sign off on some fix that allows you to not remove the brick, down the road, every thing that goes wrong is going to come back to this. You would be shocked that six years down the road, when the CFM is rusting or something, they get lawyers who can get around whatever it is they signed off on, and hold you or your friend responsible. It might not even be six years - it might be towards the end, when they lawyer around it and thus don't pay your development fee, retainage, funding of the final change orders, or other that ends up costing far more in actual cost plus the cost of resources to fight them. The time, effort, resources and angst you will expend is just not worth it. Bite the bullet and spend what you know to be a defined resource (time and money, both for the contractor/sub and the management) to remove the brick and build it properly. If you bite the bullet now, you can probably get some of the downstream parties to share in the cost or at least make the fix less costly. If you try to band aid around this and it comes back to bite you the downstream players will be long gone and even if you can find them, you won't have any leverage. Even if it causes the brick sub to walk away from their final payment and retainage rather than participate in the fix, you at least have that. There is SOME (however small) culpability here if there are even halfway decent contracts to the GC and the GC's masonry sub - they are supposed to build by the drawings. Stop expending resources to find a way around it (and for sure stop adding improperly constructed brick) and bite the bullet.
You may also find that once you are willing to bite the bullet and build it properly, the owner may be willing to work with you on the timeline...
Source: decades of experience on many sides of the construction defects issue
Thank you @ CL, I agree with everything you said and will relay this to the builder.
Between the double OSB, the spray foam, the 1/4 foam tape, the brick and the air gap, we were able to show (using ASHRAE and DCConctrarian's method) that the R value could reach 15. But we are strongly urging the builder to tear it out.
Seems like every mason on the job had to know what they were building was wrong and keep their mouth shut figuring they would get paid to unbuild and rebuild the wall padding their wallets.
With drywall screws thru 2 inches of interior foam and into the steel studs. Does anyone want to calculate if the screw heads will fall below the dew point when the indoor air is 72° & 55% humidity and negative 5° outdoors.
If my guess is correct that the screw heads will often fall below the dew point you may want to require stainless screw because they conduct less heat and will not make rust stains.
Walta
Is there any particular reason why tearing out the brick is "out of the question"? I can see how the contractor that installed it would not want to do it, but if they didn't follow the plan, it's still their problem. There are usually three kinds of "problems" in the construction world:
1 - Inspector wants to challenge something. This can be either easy/cheap or hard/expensive to deal with, depending on the what the issue is.
2 - Something "can't" be done because of a project timeline, i.e. "if we do that, we can't be done in time", etc. This is usually something that only the owner can really decide, since they are usually the ones that set the required completion date on projects with a time crunch.
3 - Something "can't" be done because it would cost someone money to do it. I kinda sorta think this might be what's going on here with your project. These are issues you need to force to be dealt with, usually by witholding payment, and sometimes with legal work.
If you have contractors that didn't follow the plan, they are responsible to fix things regardless of the cost. The only thing that could get them off the hook would be if you or the owner (assuming there is a difference in this case) told them to do something differently from the plan. On my projects, ANY time the customer asks for ANY significant change, it becomes a numbered change order that they have to sign off on for this reason -- so they are clear on the costs and any potential complications, and to keep everyone on the same page as to what is being done and why.
If your contractor made a mistake, or your GC made a mistake, and the plan hasn't changed in a way that would affect the contractor that made the mistake, then you can go after that contractor to fix things properly regardless of if they want to do it or not. The big downside is forcing these kinds of issues tends to result in project delays, sometimes lengthy ones. The upside for you is that this is really the way to fix it "right".
Bill