How to Install a Glass Block Window Before Installing a Shower

Measure the height and width of the opening in your bathroom window. Do this before you remove it. Stretch the tape measure to the outside edge of the window frame when taking the measurements. Write the measurements on a sheet of paper to take with you to the store.

Purchase the most appropriate size of glass blocks for the opening. The blocks are available in different shapes and glass thicknesses at most home supply stores. Allow 1/4-inch of space around all sides of the glass blocks when determining how many are necessary for the opening. This will allow room for the mortar.

Remove the existing wood- or aluminum-framed window with a crowbar. Use a hacksaw to remove a steel-framed window. Use a hammer and chisel to chip away any mortar that causes high spots in the window frame.

Set one horizontal and one vertical row of glass blocks in the window opening with a piece of cardboard in between each block. The cardboard represents the mortar in the finished project. Mark the walls with a sharpened pencil where each piece of cardboard rests and then remove the glass blocks and cardboard.

Seal the exposed areas of a wood frame with a wood preservative and a small paintbrush. Once it dries, set the glass blocks in place with wood shims placed tightly around the perimeter.

Mix enough mortar to fill a 5-gallon bucket -- this should be enough for one window. Mix the mortar to the consistency of bread dough. Spread the mortar onto the windowsill with a trowel. Make it even across the width of the opening. Apply the mortar up along the side of the window opening as well. This is where the glass blocks will sit next to the wall. For wood frames, use the mortar in between the blocks only.

Set the first glass block in place. Continue to fill the first horizontal row by adding mortar to the side of each block. Don't leave any gaps in between the glass blocks; fill the space adequately with 1/4-inch of mortar. Spread additional mortar onto the opposite wall to finish the row.

Check that the first row is even by setting a carpenter's level on top of the row. Adjust the amount of mortar, if necessary, to make the row level by adding more with the trowel or scraping it off. Spread mortar on top of the first row of glass blocks and along the wall area. Continue adding blocks in this fashion until the block window is complete.

Wait a couple of hours for the blocks to settle and the mortar to begin drying. Use a striking tool, such as a center or drift punch, on the joints to smooth the mortar. This gives the window a professional look and also creates a moisture-proof seal.

Read the directions on the mortar mix carefully to determine when you can clean up the excess mortar. Typically, this is within a few hours. Once the mortar firms up, wipe off the excess with a damp cloth.

Add wood trim that extends over the glass about 1/2-inch on windows with wood frames. Do this around the opening on the interior and exterior of the window. This holds the blocks securely in place. Use caulking to seal the interior and exterior of the window.