Metal Studs in Basement: barrier underneath the track atop the concrete?
TooldadNJ
| Posted in General Questions on
Hi
I’m getting ready to frame out a wall along the perimeter of our basement. We’re in New Jersey. I’ll be using metal studs for the job in front of 2″ polyiso rigid foam attached to the basement walls. I am finding conflicting information on whether to attach the metal track directly to the concrete floor. Should I put a foam sill plate underneath? Or first lay a pressure treated 2×4, then a regular 2×4 and then the metal track? Thanks in advance!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Metal studs make sense if you are building a thin 1 5/8" thick wall. For anything else, it is not worth it. The thermal bridging of the metal studs cuts your assembly R value in half, they are more expensive, harder to wire and hard to hang things off it. If your basement has enough issues that wood studs would rot, the metal studs would also rust away.
To answer your questions, you want a capillary break between the bottom plate and the concrete even with steel studs. Simplest is sill gasket material but you can also use a piece of PT. The metal track can right over the PT if it is the newer brown stuff.
Thanks for the thoughtful response. The walll is no load bearing with no electrical needed and nothing is hanging off of it other
than drywall. For what it’s worth, our local lumber yards have metal stud prices for the same as wood.
Is all the insulation in the foam behind the metal studs? That would be OK. I don't like metal studs in a wall that has insulation because the thermal bridging is so extreme.
Yes, the polyiso is attached to the wall and the metal studs would be in front of the insulation.
TooldadNJ,
Do confirm you don't need outlets. Most codes mandate them on finished walls.
The old wall had no electrical but we can certainly add outlets.