Approaches to glass block window repair depend on the extent and complexity of damaged glass. Block windows are composed of modular blocks of glass that can be placed individually to create a pattern or shape in a wall, door or other structure.

Glass blocks add a unique, fashionable look to any building. The windows are great for increasing a room’s natural light and add a special design accent. However, when one or two blocks break it can really damage the overall look.

A lot of people don’t want to take on repairing a glass block window when one- or two-pieces break out of fear they will have to remake the entire window. However, when a block breaks it doesn’t mean everything needs to be taken apart.

These helpful steps will go a long way in understanding the best approach to glass block repair.

Glass Block Window Repair – Assess the Damage

glass block window repair

The first step in glass block window repair is knowing whether a fix is worth your time and effort. A lot of people decide to leave the window alone if damage is minor.

Ultimately, it depends on how much of an eyesore the broken glass blocks are and what the chances are the damage could spread.

Not all glass block windows are created equal. Some blocks are held together with mortar and can be much more difficult to dismantle and rebuild.

Others are held together with plastic spacers and silicone sealant. Different qualities of glass mean some break easier than others. Before attempting to repair glass blocks, it’s important to make sure replacements are available.

Blocks come in a wide variety of shapes, opacity and size. The last thing you want to do is take apart a block window only to find out you can’t get a matching replacement.

Another factor to consider is whether a broken glass block presents a safety hazard. Sometimes home or business owners with a single broken glass block think it’s minor enough not to warrant repair.

One thing to keep in mind, though, is that the depth and shape of cracked glass could hurt anyone who touches it. It’s also possible that glass chips could break off and fly at anyone in the area if something hits the window.

DIY or Professional Repair

There are plenty of resources online and in your local hardware store that can help teach basic glass block repair. Likewise, there will be a good number of contractors and window repair services that can take care of the problem for a fee.

Choosing to attempt a fix yourself or hire a pro will depend on the level of damage, difficulty accessing the broken blocks, and how comfortable you feel doing home repairs.

Glass block work can be learned but takes a lot of patience to master. Here are the basics steps in glass block repair to help you know if you’re up for the task.

1. Prep the Repair

The first step to fixing broken glass into prevent any danger from shattering. Placing duct tape on the face of the broken glass blocks will help stop any splintering or glass pieces from flying around. Proper safety gear like gloves and safety glasses should be worn.

2. Break the Glass Block

Hit the glass block that needs to be removed with a rubber mallet until it breaks. Then collect all the glass shards and clean the area.

3. Remove the Mortar/Sealant 

Next the mortar holding the glass block in place needs to be removed with a hammer and chisel. If the blocks are held together by silicone sealant, a knife or razor can be used for trimming. This step requires attention because it’s easy to strike the mortar too hard or in the wrong place and break an adjoining glass block.

4. Prep new mortar/sealant

After all the mortar or sealant is removed, thoroughly clean the area and then prepare new mortar or sealant. Do some research on the best kind of pre-mixed mortar should be used for glass block repair and what consistency it needs to be for application.

5. Apply new mortar/sealant 

The first mortar or sealant should be applied to the bottom edge of where the new glass block will be placed. Applying sealant and mortar can be a tricky process.

If it’s put on too thick the replacement glass will stand out and ruin the window’s uniform look. When the glass block is placed onto the mortar or sealant, it needs to be centered before any of the sides or top is sealed. It’s recommended that sealant/mortar work is done from both sides of the window to make sure they are even.

6. Sit and wait

After the mortar or sealant work is done, let things dry. This step depends on which material is being used. Silicone sealant dries much faster, so attention needs to be paid up front to smoothing out sealant lines. Mortar drying can take several hours. Once the mortar is dried, you can go back and smooth or compress the joints.

7. Clean up with caution 

Some repairs are ruined during the final clean up stage. There’s a temptation to clean up mortar or sealant splatters with a scraper or blade, but this is a big mistake that can damage the replaced glass and other blocks around it. Glass block repairs should always be cleaned with a damp cloth to avoid scratches.

Glass block windows add a unique look to any building. They give an elegant look when used in bathrooms, windows, room dividers or other areas of a home or office.

Even though a crack or break can be disappointing, the advantages of modular design mean that often glass block repairs can be done quickly without having to take apart a large portion of the window work.

Knowing how involved block window repair can be can push some would-be DIYers to call a professional. Having a skilled window technician will make sure that the repaired glass matches the existing window and that no money is wasted on failed attempts.

Make sure you carefully weigh your options before selection options for your repair.