[Snboard976]

I am going to be finishing the basement with 3 inches of closed cell spray foam, tile floor and mold resistant drywall. I would like to use metal studs because I am concerned about humidity/moisture.

My question is how to frame the wall under the duct in the picture. I have a field stone foundation covered with a skim coat and painted with some type of water proof paint. It is not level. There is only a quater inch between the duct and the foundation. I don't want to frame inside of the duct because I would lose so many square feet.

How would you frame the wall? Can it be done with metal studs?

https://flic.kr/p/FdAe8Y

 

[joed]

If you have a moisture issue the metal will rust. Better to use one of the mold/pest resistant wood studs after you deal with the moisture issue.

 

[joecaption]

Is there still a moisture issue?
Basements need to be water proofed on the outside not the inside.
I have to agree about the metal studs.
Ducts need to be boxed in sort of like this.
https://www.google.com/search?q=box...LAhUClR4KHX0JA_MQsAQITw#imgrc=aCeje_Lq6VPR5M:

 

[Gary in WA]

Best to remove the duct and SPF or foamboard the rim areas. Right now, the heating system is drying the rim area- through the air permeable fiberglass insulation, that will change dramatically after 3" SPF in front of it. If the steel studs are in front of the SPF, no worries; http://www2.dupont.com/Tyvek_Weathe...rior Insulation Building Science Bulletin.pdf

Gary

 

[Snboard976]

Thank you for the advice Re: moisture. The question I have is how to fasten the top of the studs given the location of the duct. The track for my studs on the bottom will be bolted the slab but how can I secure the top of the studs?

 

[Gary in WA]

IMO, tie to to the concrete wall with a vapor barrier against the concrete at contact point. OR, run a wood 2x2 against the concrete (w. V.B.), just below the duct work, add a 2x2 frame (ladder) extending away from the concrete, past the duct enough to nail a a few vertical 2x2 to fasten all to floor joists above. Get creative...

Gary
PS use foil faced (or a vapor barrier plastic) foamboard under the sill plate/track of the new wall to stop moisture through the slab. Where is the house? What on the concrete walls?

 

[Snboard976]

The house is in Westchester, NY. The walls are fieldstone with a skim coat of mortar painted with drylock.

They are not level which makes running the 2x2 challenging. I think I will try what you are suggesting building the latter in sections on the floor, then put it up and using shims where necessary to tie it into the concrete.

 

[carpdad]

No spray foam. XPS sheets glue to the wall. You can't control the moisture/leak issues because the duct is in the way. Seal the edges of the xps with can foam, as long as you are sure you have no leak issues. If you don't know, don't seal the bottom, unless you are sealing to some kind of french drain. What you want is dead air space behind the xps. The duct itself looks insulated enough not to rust (soft duct?), but the rim joist/joist bay above can't be touched.
I'd test the wall first. Skim coat/stone may not hold a fastener. Coat is too thin and stone may fracture. You may be drilling/screwing into stone mortar joints which may not hold/soft.
If the basement is not high ceiling, the space under the duct maybe too low and already lost as living space. You can fill it with storage/built in and tie it to the visible floor joist. Electrics in metal wire chase/thinwall tubes and outlets in the cabinet back wall.

 

[Snboard976]

I am starting by boxing in the ducts with plywood. I was able to use a rotory hammer to screw some pressure treated 2x4s to the field stone foundation. The first piece of plywood is screwed to the joist. The second piece of plywood is fastened with screws at the corner to the first piece of plywood. The other edge of the plywood rests on a level shelf made from pieces of 1x2s.

I will frame walls with galvanized studs. Tracks will be screwed into the slab and the plywood under the ducts. The studs will be 2.5 inches off the wall. Insulation and vapor barrier will be 3 inches of closed cell spray foam.

Any thoughts?

 

[Snboard976]

Forgot the link to the beginning of the project. I messed up by putting g dita down first. https://flic.kr/p/GCBDeZ