Concrete provides a strong and stable structure for holding window frames in place, but the frames themselves cannot be set directly into the concrete surface. Instead, you’ll need to create a frame between the concrete and the window frame, providing a level surface to which you can screw the window frames in place. The creation of the frames is not a difficult process, but it does require careful detail work to ensure that the frame is fitted well enough so only small adjustments are necessary during the installation process.
- Tape measure
- 2-by-10-inch pressure-treated lumber
- Circular saw
- Carpenter’s level
- Wooden shims
- Concrete nails
- Silicone caulk
Measure the width of the window wells as well as the depth of the well from the interior well edge to the exterior well edge using a tape measure.
Cut two, 2-by-10-inch planks to fit the measured width of the window wells using a circular saw. Cut the boards lengthwise to fit the well depth.
Place one of the boards along the bottom of the window well so that the board is flush with the interior and exterior window well edges. Set a carpenter’s level onto the top of the board and adjust the board so that it’s level. Slide wood shims beneath the board to hold it in the leveled position.
Drive concrete nails through the board and into the base of the window well using a hammer. Space the nails every 5 inches along the board length.
Set the second board against the top of the window well and repeat the leveling process with the carpenter’s level and wooden shims. If you’re setting an egress window, cut and place a second board against the first along the top of the well to provide additional support. The second board needs to run the entire length of the well like the first and be butted directly beneath the first to make a double thick header along the top of the window well. Nail the top boards into place with concrete nails spaced 5 inches apart.
Measure the distance between the bottom of the top board and the top of the bottom board. Cut two of the planks to match the length of the space, and then cut the boards lengthwise to match the well depth.
Place the boards on either side of the window well, tapping them tightly into place with the hammer. Place the carpenter’s level against the side of the board to check it for plumb, and make adjusts as needed with wooden shims placed into gaps between the board and wall. Nail the side boards in place to complete the construction of the window well frames.
Seal the joints between the window well frame and the concrete of the walls with silicone caulking. Place beads of the caulking into both the interior and exterior joints to prevent leaks at the joints.
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