Fastening knee wall

I am finishing the basement and have a question around the half concrete foundation wall at the walkout level. Currently there is a 4ft half concrete wall and above the concrete it's framed to the ceiling. My idea is to Fran a half wall 4.5 inches away from the concrete wall but how do fasten it to the base plate of the existing framing that Sits on the concrete wall. I have 2 ideas
1: run pressure treated 7 inch 2x4s perpindicular to fasten the new existing wall to the existing base plate of the framing of foundation.
Or 2: build the new wall until it's flush with the concrete ledge then cap it with a 2x8 and fasten it by toe nailing the 2x8. The problem with this is that a 2x8 is 7 1/4 wide and the distance I need to cap is Only 7 inches wide so it won't sit flush.

 

Use continuous insulation (XPS) to meet minimum code for your area OR tell me the largest city near you and figure your dew-point for you..... 2009 IECC Climate Zone Map - Maine That way; min. foamboard to stop cavity condensation with required fibrous cavity insulation to meet other code stated.

Gary

 

Gary, I think you got the right answer to the wrong post.

Either framing method would work. You could even cap the perlins with a nice piece of wood for a shelf effect, allowing it to protrude slightly over your wall finish. I like option #1.

 

I like option 1 also if u can come up with a way to work with it. But if I put the 2x8 (which is 7 1/4 wide) pressure treated on top to fasten the knee wall it will over lap the new framing by 1/4 because it's 7 inches which would be a problem when dry walling.

I do plan on putting a nice piece of shelving in option 2 after it's complete.

 

Thanks, Larry. Actually I was showing (though should have explained it better) for that location in a basement, R-19 (cavity fill) is required--- 2x6 wall, not 2x4. So I suggested f.b. to stop condensation on the cavity fill then use 2x4 wall framing.

Gary