Corroded Steel Studs 1

[omoreno80]

I have a building near a coastal area that has the lower portion of the metal wall studs heavily corroded. The metal stud track and lower portion of studs have corroded to a point that the web and flanges have lost large sections of their areas. We are in process on investigating what are the possible causes. My question is whether or not shoring of the metal stud wall is required. The Contractor wanted to remove a portion of the studs that was heavily corroded up to a point, clean the remaining rusted section, and apply a corrosion inhibiting coat to the remaining section. A splice joint similar a track splice is the proposed fix to the metal studs. The bottom of the metal studs where originally fastened with TEK screws, so the stud wall behaves as a simple span with little to no moment at the ends. The wall is load bearing. I was wanting to shore up the entire roof that is supported on the wall to perform the fix. The Contractor wanted to repair each stud by providing minimal support. I could check to see where the top plate splices occur and check to see if the areas in which the member is continuous can clear span two stud bays. Studs are spaced at 16" o.c. The roof is also light gage steel studs. I have attached a picture of a section of the wall, pre-inspection.

 

[msquared48]

I have attached a picture of a section of the wall, pre-inspection.

That did not post.

Personally, before the fix is made, I would determine why it happened in the first place - there is a salt intrusion somewhere, air or water borne, and it needs to be sealed before the fix is undertaken.

Personally, I would replace the entire steel stud track and double up on the existing studs, back to back, and that will require a full shore, not a half-ass approach in my opinion.

Mike McCann
MMC Engineering

 

[wannabeSE]

How does the contractor propose to attach the bottom? There are a number of ways to do this. But, I like your original idea of shoring the whole mess and replacing the studs and track as required.

Also, you may want to check the zinc coating thickness on the existing framing. A G60 coating is typical for exterior walls. For the replacements, you might want to check the price and availability of framing with a G90 coating. See

http://www.cfsei.org/PDF/DesignGuid...Cold.Formed.Steel.Framing.Members.Sept.04.pdf

for more information n coatings.

 

[dik]

Good publication...

Dik

 

[Ron]

First, shore the wall before repairing. With the corrosion you have described, there has likely been some downward movement of the framing.

Next...I'm not sure what code you are under, but you typically cannot scab an existing defective stud. The new stud must be full height. Sistering is acceptable, but splicing is not.

As for cleaning and coating in the field....waste of time. You will NEVER get a coating in the field as protective as the original galvanizing. Take out all corroded members and replace them. Since it is along the coast, I agree with wannabeSE...use G90 spec.

Hopefully you have determined the cause of the water intrusion and will correct it after the structural repairs. If not, you'll do it again in a few years.

 

[CELinOttawa]

As others have said, you really need to solve the problem of why the corrosion has occured, but a Structural repair is never a bad idea... Similarly I have a basement where the owner called us in to do new windows in a building from 1942. The foundation turned out to have bad deterioration, so we've specified repairs and have cautioned that unless the source of the deterioration is found, they will be repairing again soon. In any case, the repair must happen, so whether or not they continue on and do the right thing is not, strictly, my concern. I've advised what would be best, addressed what is life safety, and feel I have fulfilled my mandate and obligation to the public. You may be facing a similar situation if the client doesn't want to pay for an investigation and would rather just patch.

You can lead the horse, but not make it drink....