Dry Stacked Block Wall Insulation Page
Attach rigid foam to the walls
This image shows the installation of 2-inch rigid foam wall insulation on a concrete block wall. It is affixed using vertical 1×4-inch boards spaced on 2-foot centers. For attachment, 4-inch concrete screws secure the 1×4-inch boards onto the concrete wall through the 2-inch foam insulation. Rigid foam panels were trimmed down to approximately 9-feet in length to match the wall’s height (14 blocks).
Sheet rock fastening details
Attach the drywall to the vertical 1×4-inch boards using standard 1-1/4-inch drywall screws. Watch this related video for a visual demonstration. In the wall picture (at the top) note the absence of horizontal drywall boards at the top and bottom of the walls. Affix the upper part of the drywall to the ceiling drywall using fiberglass tape during the application of joint compound. After 8 years, these ceiling joints remain intact due to the stability of the concrete walls.
No horizontal boards at the wall’s bottom is significant and acceptable because:
- 3/4-inch gap between the foam and the drywall requires no draft sealing. The SBC coated concrete walls eliminate drafts.
- Vertical 1×4-inch boards are attachment points for the baseboards, which safeguard the lower edge of the drywall.
Positioning 1×2-inch boards around the window and door frame aids in attaching the drywall. Position 1×6-inch boards horizontally where electrical outlet boxes are installed, . Wall switch/outlet wires run down from the attic to the switch/outlet boxes. Grooves cut into the foam allows cable embedding and then cover with foil tape or other appropriate tape.
Window installation with foam insulation
Below are pictures of an attached-garage flange-type-window. In the top left picture, the concrete window header isn’t insulated. In the house the window rough opening includes the top 1×4 boards for attaching the header sheet rock. You can also add 2 more inches to the window opening surround making space for 2-inch rigid foam under all the window surround sheet rock.
