Can You Replace Just One Glass Block in a Window?

If you have a glass block window and one of the blocks becomes damaged, you may be wondering if you can replace just that one block without having to replace the entire window. The good news is that it is possible to replace individual glass blocks in a window grouping without having to remove the entire window.

Removing the Damaged Glass Block

The first step in replacing a single glass block is to remove the damaged block. Here’s how to do it:

Cut strips of furnace duct tape and place them over each face of the glass block that needs to be replaced.
Put on safety glasses, work gloves, and a long-sleeved shirt. Strike one face of the glass block using a rubber mallet until the glass breaks. Repeat on the remaining face of the glass block. Place duct tape and any glass shards in a bucket.
Vacuum to remove any shards and slivers of glass.

Chipping Out the Mortar

Next, you’ll need to chip out the mortar surrounding the damaged glass block using a chisel and hammer. Be careful not to chip or crack any of the glass blocks adjoining the one you just removed.

Installing the New Glass Block

Once the damaged block has been removed, you can install the new one:

Mix up some pre-mixed mortar with water to the consistency of bread dough.
Using a trowel, place a layer of mortar on the bottom surface the new glass block will be resting on. Match the thickness of the mortar to the existing mortar joints.
Slide the new glass block into the opening and center it. Start packing mortar into the spaces on the three remaining sides of the block. Do this from the inside of the building and the outside. Pack the joints until they are completely filled.
Wait for the mortar to get firm, about two hours, before taking a striking tool–a narrow, spatula-like tool used to smooth and compress the mortar joints. The striking tool gives the mortar joint a clean, professional look.
Wipe the glass block clean of any mortar with a soft, damp cloth.

By following these steps, you can replace a single damaged glass block in a window grouping without having to replace the entire window. This can save you time and money while restoring the look of your glass block window.