Metal studs on exterior basement walls?
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I bought a house and now I’m planning on finishing the basement and have questions about insulation and moisture. The house was built in 1993, should be dried out, and doesn’t show any evidence of being wet. Regarding climate, I live in <!—-><!—-><!—->Detroit <!—-><!—-> area, roughly.
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I’ve read some of the stuff from the http://www.buildingscience.com/ website; most information seems reasonable. For basement walls, one suggestion is to use foam board (e.g. EPS) with a perm rating of >1 to allow the wall to dry to the basement interior, which should work if you don’t use foil or polyethylene vapor barrier or vinyl wall coverings, and they say latex paint on gypsum board will provide a semi-permeable vapor retarder.
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So, I’m planning on using 1†EPS (2†would be less than 1 perm…) and drywall, but I’d like to use metal studs between the EPS and the drywall to get straight walls. Will this be okay, or is this likely to be troublesome in terms of water condensation?
Replies
That will work fine. I can send some pics of similar work later. At 1" you can use XPS (according to Building Science) and it is MUCH easier to attach to the walls and seal the seams than the floppy EPS. You can save on wall thickness by using 1 1/2" 20 gauge steel studs. Leave a small gap between the foam and the studs and you can run wiring behind the studs. Squirt some spray foam between the studs and the foam wall panels every 16-24 inches. This will stiffen the studs and keep the panels on the wall in case the foam panel glue loosens over time.
An important point -- put strips of 1/2" or 1" XPS foam between the wall plates and the cement slab. This will reduce heat loss through the steel framing to the slab and help prevent any ghosting on the drywall.
Billy
Thanks, that's great feedback. I would be interested in those pictures if you can find time...
I'm also thinking using WireTracks wiring channels (baseboard and/or crown molding), so I don't know if I'd run wires behind the studs...perhaps I'll run the power wiring behind the studs and run signal wires (for ever-changing computer/TV/phone networks) in the baseboard WireTracks for easy updating.
Thanks again for the concrete suggestions.
I'm not a home builder, just a DIYer (= home-wrecker?). If I plan on insulating the concrete floor, using either EPS and plywood or something like DriCore, should I do the floor first and build the wall on top of the floor, or insulate the walls first and build the floor up against the wall? That's probably a dumb question, but...I don't know the answer off the top of my head.
What I've done is insulate the walls, then insulate the floor (so the foam on the floor is attached to the foam on the walls, like an ice chest), and then build the walls on top of the plywood that is laid on top of the foam on the floor.
The downside is that if you ever have to or decide to replace the floor you need to remove the walls first, or cut the floors away from the wall.
So, there are at least two ways to do it, and I wouldn't say that either one is the best in all situations. I hope that helps...
Billy
Thanks again for your thoughts; I'll likely use all of your suggestions.
Andrew
You should also check out a recent FHB article by Andy Engel on refinishing basements. There have been several chats on the subject such as the one here:
http://forums.taunton.com/tp-breaktime/messages?msg=53023.1
The SEARCH function is your friend.
billy
Can I find what you have outlined in the Building Science site? Sounds like a very logical way to approach the age old finishing the basement project.
Do you attach the foam to the block wall with panel glue then set the studs then drywall? What about running the wires in the studs instead of behind the studs?
Check out this detailed article, beginning around page 10 (pages 16-20, 25, and 28-30 of the PDF):http://www.buildingscience.com/resources/mold/Read_This_Before_You_Design_Build_or_Renovate.pdf
Also, check out the details for a building in your your climate:http://www.buildingscience.com/housesthatwork/default.htm
You can attach the foamboard with a sticky quick-grab adhesive. PL Premium is sticky but it may be overkill. You can brace the foam with boards while the glue dries.
With 1 1/2" metal studs you don't want to run the wire through the studs unless you are certain that you will always use very short screws for the drywall... Behind the studs is easier and safer, if allowed by your code. Use wire ties to secure the wiring. Also use the correctly sized electrical boxes for a shallow wall.
Billy
Edited 11/9/2005 9:11 pm ET by Billy
Edited 11/9/2005 9:14 pm ET by Billy
P.S. This is good stuff, another large file from Building Science. Lots of photos that speak for themselveshttp://www.buildingscience.com/resources/presentations/buildboston/06-foundations.pdf
http://www.buildingscience.com/resources/presentations/buildboston/07-walls.pdf
Billy
Edited 11/9/2005 9:20 pm ET by Billy
Thanks Billy, lots of good stuff.
Here are a couple more, pre-drywall.
Billy
Are you using a different foam on the wall and the floor?
This is the system that Engel used, right?
Andy Engel used EPS on the floor and that is what I used. So the floor in the pics is the same as Andy's but the walls are different -- they are XPS.
The XPS is more rigid than EPS so it's easy to use. The walls would be a PITA with that floppy EPS...
The next time I will use XPS on the floor (but not more than 1 inch thick b/c of the perm rating. I found that the EPS is not rigid enough for my taste and you do get small dips when fastening the plywood to the slab through the EPS using tapcons. Maybe I should back off on the impact driver...
Billy
Edited 11/9/2005 11:09 pm ET by Billy
Many thanks.
Here are a few pics.
Billy