Framing a wood studded wall against a concrete block wall

miamicuse

I need to frame a wall against a concrete block wall. This is a normal wood studded wall with a pressure treated bottom plate, top plate and wood studs spaced every 18".

The problem is the concrete slab is ever so slightly higher where the floor meets the block wall. So when I pushed a PT 2x4 against it as the bottom plate, the plate is not level. So the front lip of the 2x4 is a little lower than the back, may be by about 1/8".

Is this significant enough?

Do I shim along the entire front of the bottom plate to get the plate level? Or should I cut each stud a little skewed to account for the difference?

joecaption

Your not suppost to install the wall tight to the block anyway. Just move it out where it's flat.

miamicuse

I wish I could but I need that space.

cortell

Like Joe said, you definitely don't want to frame right up against the block. Go out at least an inch; more if you need it to reach the level plane. In between the block and the wall frame, install rigid foam. This provides both a thermal break and a vapor retarder. Make sure to tape the seams well. In between the studs, install batt insulation for a more substantial thermal break.

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ben's plumbing

you only need min distance from wall ..just not up tight to block....

Gary in WA

If a partition wall, just shim the top plate to framing above. Is it a garage wall, basement wall, or house on slab grade wall?

As it's on a slab (if on the earth) you need sill sealer under the bottom plate for a thermal/capillary break to prevent water wicking to the studs: http://www.greenbuildingadvisor.com/...-building-code

I hope the 18" layout is a typo...

If against an house exterior block wall, only a v.b. is required for untreated vertical studs touching concrete; http://publicecodes.citation.com/ico...9_3_sec017.htm

Gary

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Charles S.

I've been in construction more than 20 years. Everyone is telling you the right thing; don't build it touching the block wall; or you run the risk of it rotting with the killer being the condensation which is the thing which prevents every exterior masonry wall to be dry every day and night when it's humid, dark and warm/cold alternating days, such as fall/winter/spring bring to various parts of the country. I've replaced roof plywood more than once due to those folks building a room up against the rafters, pressing the insulation, and not having a ventilation space for the condensation---which is going to form regardless---to be able to then dry out instead of turn to mold.

The sill might be done any of those ways, but you might find it easier to build the wall on the floor, then stand it up. Any spaces underneath the sill can be filled with shims at the 18" marks, maybe some liquid nail...

hand drive

a few shims placed under the front of the plate along with liquid nails used underside along the entirety of the plate will help get it level.

It will most likely work best to bring your wall a 1/2" or so off of the block wall. that way you can make your wall vertically plumb regardless of the block wall. Also it is good to seal the block wall behind new stud wall if it has not already been sealed.