How to Install Glass Block Windows With No Mortar

Prepare your window opening by removing the old window, cleaning up the window jam and checking for plumb and level.

Size your new window space by first determining the dimensions of your glass block window. To do this multiply the size of the glass blocks by the number of blocks you plan on using. For example, if you are using 4-inch by 4-inch blocks and you plan on creating a four block by four block glass block window, then the dimensions of your new window will be 16 inches by 16 inches. If your old window opening is too big you can reframe the opening by screwing 2-inch by 4-inch pieces to the old frame.

Install the mounting channels for your mortarless glass block window. To do this, place the channels on the window opening and screw them down using one inch zinc plated drywall screws.

Test fit your block windows by assembling them in the space. Make adjustments to the window opening using shims so that the blocks will fit snuggly.

Build your glass block window in the fitted window opening by connecting them with plastic connectors. Then seal the assembly with silicone adhesive or sealant. Make sure you caulk around the outside perimeters of the glass block window as well as the interior joints.