Replies

1. GBA Editor
   Martin Holladay | Jun 21, 2013 01:25pm | #1

   Freddie,
   Presumably, you have filled the cores of your block with rebar and grout -- right? So the top of the wall has no holes in it -- just cured grout.

   The product that you need to use between the top of your block wall and your pressure-treated sill plate is called sill seal. You can buy it at a lumberyard or building supply store.

   Sill seal made of closed-cell foam is better than sill seal made of fiberglass.

2. Expert Member
   Dana Dorsett | Jun 21, 2013 05:26pm | #2

   Depending on just how even & smooth the top of the foundation is the sill seal alone may not be very air-tight. Laying a bead of can-foam on the top of the foundation between foamy sill seal and the wood as you go will usually take care of that. Even on poured concrete foundations where the top had been left a bit rough the sill seal isn't always reliable. Works great on even moderately trowel-finished concrete though.

   This video is is a reasonable representative sample of the type of sill seal, being used on a troweled slab foundation:

   https://www.youtube.com/watch?v=VHF74HQPZtM

3. 
   user-939142 | Jun 23, 2013 05:51pm | #3

   Generally, insulation is not placed on the foundation wall between the sill plate, and it more than likely won't meet code anywhere. With an engineer you could potentially confirm the use of a high psi foam.

   You want to use the sill seal mentioned, but it serves as a break and seal, not insulation.

   Placing a small strip of insulation between doesn't do much if you think about it. If your wall is so temperature different between foundation and wood frame, you need to insulate the foundation wall.