Glass block windows are the perfect way to incorporate natural light without letting passersby see into your home. While installing these windows might seem challenging, the project is much easier than installing traditional windows. With a few tools, materials, and a couple of hours of labor, you’ll have a beautiful glass block window.

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How To Install a Glass Block Window

Source: Canva

Once you decide to install glass block windows, you can outsource the project to a professional or complete it yourself. If you choose to DIY the project, you’ll need to gather materials, take careful measurements, and more. Here’s what you’ll need to DIY a glass block window installation:

  • Carpenter bar or pry bar
  • Chisel
  • Circular saw or reciprocating saw
  • Damp sponge
  • Glass silicone
  • Glass block window
  • Grout bag (optional)
  • Level
  • Measuring tape
  • Mortar and sealant
  • Shims and spacers
  • Trowel
  • Tuck pointer 
  • Utility knife
  • Wide masking tape
  • Work gloves

Once you’ve gathered your tools and supplies, follow the steps below to complete your glass block window.

1. Measure the Window Space

Before you select or order your glass block window, you need to measure the space where it will go.

You’ll need accurate measurements, so it might be easier to remove the old window before working through this step. However, if the project will take you a few days (or you need to wait for the window to ship), removing the old window before installing the new one isn’t feasible. 

If that’s the case, do your best to work around the window for accurate measurements. Measure the window space, ensuring you measure down to the masonry or wood. Don’t measure the current window box — you may need to remove it later, so it’ll throw off your measurements.

In some cases, you might be able to keep the old window jamb — it all depends on the situation. If the wood frame will interfere with the installation, remove the jamb. You can also remove the jamb if you prefer the look of a fitted glass block window without a window box. 

It’s usually best to remove the frame if you’re using a vinyl-framed glass panel block window. Adjust your measurements accordingly if you decide to keep the window box jamb.

Once you finish measuring, note each measurement, then measure again. It’s best to measure at least twice, as mistakes later down the line can be pricey. Once your measurements are consistent, move on to the next step. 

2. Select the Right Glass Block Window

With your measurements in mind, it’s time to choose the glass block window for your project. You may be able to buy one from a home improvement store that will work for your project’s measurements, but you may need to custom order it. 

In this step, you’ll need to consider your expectations and design preferences. Glass blocks come in multiple styles, including diamond, ice, and ribbed. As you browse for the perfect style, remember to consider privacy needs. Some styles offer more privacy than others by distorting the glass, so they work well for windows in bathrooms and other areas requiring privacy. 

3. Remove Old Window and Prep

When you’re ready, your next step involves removing the old window and prepping for its replacement. During this step, you’ll need to wear gloves to protect your hands if the glass breaks. 

If it does break during the removal process, carefully clean it up. Generally, using a shop vacuum will do the trick — and you won’t risk damaging your home vacuum cleaner). 

Once you remove the window, remove the jamb (if applicable). To remove the jamb (if it’s made of metal), use the pry bar to pry it out of the window box. You may need to cut through a layer of caulk or paint holding the jamb in place. Use the chisel to clean up any leftover caulk or paint in the window box. 

If the window box is made of wood, use a saw to carefully cut through the wood in the middle of each board. Be careful not to cut into the material underneath the window box, as this could ruin the saw blade. Use the pry bar to pry the wood out of the window box. 

Or, if you decide to keep the window box, leave it where it is. You might need to chisel away some of the window frames to make room for the window block. Ensure the opening is nice and clear before installing the window. 

To avoid making a mess with the mortar and staining surrounding masonry, place a layer of masking tape around the edge of the window space. Avoid placing the tape directly where the window will sit, as you won’t be able to remove the tape later. 

4. Mix and Apply a Bed of Mortar

After preparing the window space, mix the mortar you’re using according to the manufacturer’s instructions. The consistency should resemble that of cookie dough. If you’re placing the glass block window on masonry, you’ll need to use mortar to set the window. 

Layer about a half-inch of mortar on the base of the window space and smooth it out with the trowel. Place a few shims across the window space on top of the mortar. Press them gently into the mortar, so they don’t move.

5. Install Glass Block Window Panel

Now it’s time to install the glass block window. For this part of the process, you’ll need a helper. Maneuvering these windows into place can be tricky since they’re often fairly heavy, so enlist the help of a friend. 

When you’re ready, lift the glass block window into the space from the outside. You can either tilt or slide it into place. Have someone stand inside the house to steady the window and prevent it from falling inward. 

6. Level and Mortar the Panel

With the window in place, it’s time to ensure everything is level and seal it in. Use a level to ensure the window is evenly placed and completely upright. Once you ensure it’s level, take a few shims and wedge them into the gap on the top of the window. This will hold it in place as you work. 

Use the level to recheck the window (make sure it didn’t move while installing the shims). If everything looks good, you can fill in the gaps with mortar. 

Fill a grout bag with mortar and pipe it into the gaps, or use a trowel and tuck pointer to work the mortar into the gaps. Continue working the mortar in until there are no air pockets or empty spaces. Smooth your work as you go. Complete the same process inside the window to ensure all gaps are full of mortar. 

Give the mortar approximately half an hour to set, then remove the shims. Fill those holes with mortar and smooth the area. For an extra professional touch, dampen an old paintbrush and run it over the mortar joints. 

Use a soft cloth or sponge to clean up the mortar on the glass, ensuring you don’t scrape into the still-drying mortar. 

You can add reinforcements with anchors and rods, but this step is unnecessary with premade glass block windows secured with high-strength masonry mortar. The mortar is strong enough to secure the window without adding anchors and rods. Generally, anchors and rods are only necessary when you use individual blocks to construct the window or use lower-strength mortar. 

8. Seal With Caulk

After about 24 hours, apply a layer of glass block silicone caulk to seal the window. Carefully caulk around the window, filling in gaps between the sill plate and glass. If you get caulk on other parts of the window or mortar, clean it up immediately with soapy water. 

9. Clean Any Mortar or Caulk Residue

Last but not least, clean up your new window installation. Use soapy water to remove caulk (as long as it hasn’t dried), or carefully scrape it away with a utility knife (if it’s dried). Use a damp sponge to remove the whitish mortar film from the areas of the window you cleaned while the glass block mortar was setting. 

Glass Block Window Installation Cost

The cost of installing glass block windows varies dramatically based on a few factors. For example, the size you need plays a major role in the project’s final cost. Larger projects like a glass block wall will cost more. Smaller projects like an egress window are less expensive. 

For example, a 25-by-25-inch glass block window costs $60 to $300, while a 48-by-48-inch glass block window costs anywhere from $155 to $840. In addition, the finish and style you choose can affect the project’s final cost. Clear blocks are usually less expensive than colored, frosted, diamond, or ice glass blocks.

Keep in mind that glass block windows provide better insulation than standard pane windows, which could help with energy efficiency. This can reduce your monthly heating and cooling bills. 
Aside from the glass block panel itself, you’ll need to pay for the materials, which should cost less than $50. If you need to buy the tools for the project, such as the trowel, tuck pointer, and level, you can expect to pay more overall.

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DIY vs. Professional Glass Block Window Installation

Once you decide to install glass block windows in your home, you have two options: DIY the project or have a professional handle it. 

Most folks don’t have any issues installing these windows, and many consider it a beginner-level project. However, if the window is in a hard-to-reach place or there’s damage to the material around the existing window, it might be best to leave the project to a professional. 

If you decide to DIY the installation, you’ll save yourself some money. On average, the project takes about a day, plus the dry time between the mortar and caulk stages. If you have the time and are comfortable completing this type of project, then go for it.

On the other hand, you can always outsource the project to a professional. Window and glass companies in your area usually offer installation services, although this may vary from one location to the next. If your local glass company doesn’t provide installation services, you can also hire a handyperson to handle the task. 

Homeowners pay anywhere from $400 to $1,100 for each glass block window they install, with most paying approximately $800 per window. Costs may vary based on the installation difficulty and labor costs in your area. 

For example, if you hire a professional to install individual blocks for your glass block window, you can expect to pay more than if they install a premade glass block window. Assembling these windows with individual blocks takes longer, so labor costs would be higher. 

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Final Thoughts

Glass block windows can be the perfect finishing touch to bring light into your bathroom or basement without sacrificing privacy. Installing these windows yourself is doable with about a day, a few materials, and patience, but you can always outsource the project to a professional.

Editorial Contributors
Jonathon Jachura

Jonathon Jachura


Jonathon Jachura is a two-time homeowner with hands-on experience with HVAC, gutters, plumbing, lawn care, pest control, and other aspects of owning a home. He is passionate about home maintenance and finding the best services. His main goal is to educate others with crisp, concise descriptions that any homeowner can use. Jon uses his strong technical background to create engaging, easy-to-read, and informative guides. He does most of his home and lawn projects himself but hires professional companies for the “big things.” He knows what goes into finding the best service providers and contractors. Jon studied mechanical engineering at Purdue University in Indiana and worked in the HVAC industry for 12 years. Between his various home improvement projects, he enjoys the outdoors, a good cup of coffee, and spending time with his family.

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