How to Install a Glass Block Garage Window

Remove your old garage window from the window frame. The process for this step will vary based on the type of exiting window you have and the material from which your garage is constructed. If you have a concrete garage and the window frame is molded into the wall, leave it in place. If not, remove the window frame, any sashes or sills, or other obstructive elements as well using your crowbar.

Measure and cut your 4-by-8 foot plywood sheet to fit the dimensions of your window opening. The idea is to create a sleeve of sorts, out of plywood, into which the glass block will slide. This provides you with the opportunity to level the opening using shims placed between the plywood and the wall. Use your hammer and nails to fasten the plywood strips to the edges of the opening. Use your level to check that each of the four sides is plumb and use your shims to adjust each side as necessary.

Use your tape measure to record the dimensions of your window opening inside the plywood sleeve. Calculate the size of the block panel you will need to seal the opening. Allow for about 1/2 inch on all sides of the window for mortar and caulking space.

Use your table saw to cut a 2-by-4 inch stud into three triangular wedges which measure about 8 inches in length and about 2 1/2 inches at the widest end. These wedges will help you to space the block panel properly during installation. Lay two of your wedges on the bottom ledge of the window opening, onto which your glass block panel will be placed. Place one wedge about 3 inches from each corner and save the third wedge for later.

Cut a 6-inch block from your 2-by-4. Use your screw gun and drywall screws to fasten a 6-inch length of your 2-by-4 into the top of the window opening, so that your glass block panel can rest on it when installed.

Slide the glass block panel into the window opening and onto the tips of your bottom wedges. Lean the panel against the 2-by-4 inch block at the top of the frame and use your hammer to drive the bottom wedges in to a height of about 1/2 inch. Slide the glass panel from side to side until it is properly centered. Check the position of the panel in the frame with your tape measure by comparing the space at both side edges.

Lay your level across the bottom wedges and check that they are plumb with one another. If not, adjust until they are. Once level, insert the third wedge from the inside of the window opening, into the space below the center of the panel.

Prepare your mortar mix according to the manufacturer's instructions. Use your trowel to shovel mortar into the space beneath the panel until the entire gap has been filled. Leave the wedges where they are until later. Form a slanted ledge with your mortar so water and debris roll away from the bottom of the panel. Allow the bottom mortar to dry for the period recommended by the manufacturer before moving on.

Remove the wedges before the bottom mortar sets completely. Fill in the gaps with more mortar. Move to the gaps at the sides of your panel and repeat the mortar process. Allow these to dry before moving on. Use your striking tool to smooth and finish the side mortar fill.

Use your caulking gun and silicone caulk to seal the gap at the top of the window. Allow the caulk to dry according to the manufacturer's instructions.