Patrick.C

Framing against block wall

My basement (and future site of my home theater) is mostly underground with a door in one corner where the lot slopes down. The inner part of the space is already framed around the stairs and I will be framing against the perimeter block walls. Most of the HT contruction photos that I've come across on the web have had conventional framing done against block or poured walls. But the friends and family that I've consulted with on this project have all suggested nailing the studs directly to the block "face down" as opposed to normal framing where only the edge of the stud is against the wall. When I inquired about insulation, the reply was "What insulation? You have the best insulation going - you're underground.". Nailing the studs directly to the wall would certainly be easier, but I want to do it right if that isn't the proper way.

Opinions?

DaveHo

Even though you live in a warm climate I wouldn't recommend that. There will still be a temperature differential between the finished and unfinished sides of the wall. Moisture will move from the warmer finished side to the colder unfinished. The lack of a vapor barrier and the lack of airflow over the block wall caused by nailing directly to it could spur mold growth. Not to mention the fact that it will be a pain to do any wiring on those walls as you'll be forced to use the shallow electrical boxes. That is how basements used to be framed out in the old days...

-Dave

Nick P

I concur with Dave. Go with traditional framing held off the foundation by 1 inch and insulate the new stud wall.

Patrick.C

Why 1 inch from the floor? And how is this done? Stacked soles?

MarkMel

He means build the wall 1" from the block wall. Leave a 1" space between the bloc wall and the conventionally framed wall.

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Aaron Gould

I put in Roxul rock-wool in place of standard insulation. According to the Roxul's specs, it resists moisture, thus greatly reducing the possibility of mold/mildew.

Nick P

What MarkMel said. You want the airspace to prevent moisture transfer to the wood studs. For the bottom 2x4 plate you should use a pressure treated stud.

Patrick.C

Ok - got it. Is there a need for an extra layer of insulation then to fill the extra depth?

PhilBoy

When I framed my basement, I built the walls on the floor (I think 1/4" shorter than the lowest ceiling height), so that when the wall is finished you simply 'flip' it up into place.

Before lifting the wall into place, I backed the framed wall with black construction (roofing) paper, thus giving an additional moisture barrier against the block wall and a back to hold the insulation in place.

simplicity is genius...

David WS

I used a paint/concrete sealer on my block walls first, then I framed with 2x4 studs, insulation, vaporbarrior (8 mil poly) and finally drywall. My basement is noticably more comfortable. I've read that as much as 1/5 of your heating costs can escape through cinderblock basement walls. Do what others above mention. You'll never regret doing the extra work to make it right, you will regret doing it on the cheap or lazy.

Just my $.02

Dave

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Patrick.C

Dave - is your framing an inch away from the wall and is the poly vapor barrier between the drywall and the studs or the studs and the block?

David WS

The studs are right up against the wall. The vapor barrier is between the studs and the drywall.

bloack Wall -> paint/sealer - > studs -> insulation(between studs) -> vapor barrier - > drywall.

I didn't leave a space between the blocks and the studs for two reasons. 1) I didn't want to lose the space. 2) I kept thinking that it would give a mouse or other creature a perfect place to live.

I don't have a mouse problem or anything but it just seemed like a bad idea. I could see a whole mouse society living in that space. Maybe I'm just parinoid.

Dave

Oh, they have the internet on computers now... Homer J(ay) Simpson