Whether your basement is finished or unfinished, you probably do not want your neighbors staring into it. Curtains are one way to add privacy, but glass block windows are a more stylish and permanent solution. It costs between $250 and $500 to install glass block windows in the average basement and this project takes only one day.
You will need:
• Glass block
• Tape measure
• Pry bar
• Cold chisel
• Circular saw or handsaw
• Utility knife
• Wood block
• Rubber mallet
• Striking tool
• Margin trowel
• Pointing trowel
• Acrylic latex or silicone caulk
• Caulk gun
• Shop vacuum or dust brush
• Work gloves
• Eye protection
Step 1: Use the tape measure to measure each window opening from the outside. If the existing windows are built into the foundation, measure the entire width of the opening, as if you had already removed the frame. Record the width for each window.
Step 2: Measure the height of each window opening, going from the top of the home foundation wall to the steel or wood support. Since you will be removing the windowsill, ensure that the sill thickness is included in the height. Tap the sill to determine whether it is removable. If a hollow sound emits, the sill should come out easily. If the sill seems permanent, measure height from its top. Record the height of each basement window next to its width.
Step 3: Double-check all measurements and then take these to a glass-block retailer. This professional will assist you with ordering the correct size glass block panel. Inform the retailer whether any vent openings will be required on any windows.
Step 4: Remove the old window and cut the wooden sill with the circular saw or handsaw. Do not cut through to the concrete. Cut through any paint or caulk with the utility knife. Use the pry bar to remove the side and head jambs and the sill. If this sill is on a mortar curb, a cold chisel may be needed to chip it away before the sill can be cut and pried loose.
Step 5: Screw the temporary wood block into the underside of the windowsill plate with the drill. This keeps the glass block from tipping inward. Ensure that the block extends down enough to touch the upper edge of the glass block panel. If the window opening does not have a sill plate, screw the block into a joist.
Step 6: Cut three wedges from the 2×4, making them thicker and longer than needed. Sweep or vacuum the window opening. Place one wedge at each end of the bottom of the opening and set the glass panel on these to steady it.
Step 7: Have a helper assist you with tipping the glass block panel into place and adjusting the position. First, center the panel in the opening and then tap the wedges in with the rubber mallet to raise it until it sits 1/8 to ¼ inch from the sill plate. Lay a level across the two wedges and adjust wedge placement to achieve level. Have the helper insert the third wedge inside the window near the center of the panel.
Step 8: Mix a small batch of mortar in the bucket and place it on a wood scrap. Pack mortar under the glass block panel to build up a curb. Smooth this area, staying clear of the wedges. Allow the surface to harden to the touch and then begin packing the sides with the pointing trowel and margin trowel.
Step 9: Go inside the basement, slice off any clumps, and fill in any voids. A sloped curb can be built inside the basement or the curb can be cut flush with the glass block panel. The second approach leaves a flat surface for trim board in a finished basement.
Step 10: Once the mortar is a bit still, use a striking tool to smooth all joints.
Step 11: After allowing two to five hours for the curb to set, remove the three wedges and fill in the gaps on the curb.
Step 12: Use the caulk to seal all gaps between the sill plate and the window on both the inside and outside.
Step 13: Do not paint the new mortar for at least two weeks.