How to Install Glass Block Windows: A Step-by-Step Guide

How To Install Glass Block Windows

Glass block windows are becoming increasingly popular among homeowners due to their stylish appearance and energy efficiency. They allow natural light to flow into your home while still providing privacy and insulation. Installing glass block windows may seem like a daunting task, but with the right tools and knowledge, it can be a simple DIY project. In this article, we’ll take you through the steps of installing glass block windows.

Materials and Tools Needed

Proper mortar application is essential for a secure installation.
Proper mortar application is essential for a secure installation.

Before you begin installing glass block windows, it’s essential to have all the necessary materials and tools. Here are the items you will need:


  • Glass block windows
  • Mortar mix
  • Spacers
  • Silicone caulk
  • Trim


  • Measuring tape
  • Level
  • Hammer
  • Chisel
  • Drill
  • Trowel
  • Caulking gun

It’s essential to get high-quality materials for the best results. You can purchase these items from a local hardware store or online.

Measuring and Preparation

The first step in installing glass block windows is to measure the window opening accurately. Measure the width and height of the opening, and then add a 1/2 inch to each measurement to allow for the mortar. You should also check if the opening is square by measuring the diagonals. If the measurements are equal, the opening is square. If not, adjust accordingly.

Once you have the measurements, prepare the opening for installation. Remove any old window frames or debris from the opening. Use a hammer and chisel to remove any excess mortar or debris from the edges of the opening. Then, clean the opening thoroughly to remove any dirt or dust.

Installing the Glass Block Windows

Once you have prepared the opening, it’s time to install the glass block windows. Here’s a step-by-step guide:

Laying out the Blocks

Start by laying out the glass blocks on a flat surface. Make sure the edges of the blocks are clean and free of any debris. You can arrange the blocks in any pattern you desire, but make sure they fit the dimensions of the window opening.

Applying Mortar

Next, mix the mortar according to the manufacturer’s instructions. Use a trowel to apply a layer of mortar on the bottom edge of the window opening. Then, apply mortar to the sides of the opening where the blocks will be placed.

Placing the Blocks

Take the first glass block and place it on top of the mortar at the bottom of the opening. Press down gently to secure it in place. Then, place the next block next to it, leaving a small gap between them.

Applying Spacers

Insert plastic spacers between the blocks to ensure they are evenly spaced. Make sure the spacers are level with the blocks. Continue placing the blocks, applying mortar as needed, until you reach the top of the opening.

Sealing the Blocks

Once all the blocks are in place, allow the mortar to dry for a few hours. Then, remove the spacers and apply silicone caulk around the edges of the blocks to seal them. Finally, add trim around the edges to give the window a finished look.

Finishing Touches

After installing the glass block windows, there are a few finishing touches you can add. Here are some suggestions:

Applying Silicone Caulk

Use a caulk gun to apply silicone caulk around the edges of the glass blocks. This will help to seal the blocks and prevent any drafts.

Adding Trim

Add trim around the edges of the glass block window to give it a finished look. You can use wood, vinyl, or aluminum trim, depending on your preference.

By following these steps, you can easily install glass block windows in your home. Once installed, they will provide natural light, energy efficiency, and privacy for years to come.

Finishing Touches

After installing the glass block windows, you need to apply silicone caulk to seal the gaps between the blocks and the frame. This will prevent air and water from seeping through the gaps. Use a caulking gun to apply a smooth, even line of caulk around the edges of the window. Make sure to fill in all the gaps and smooth out any excess caulk. Allow the caulk to dry completely before moving on to the next step.

Next, add trim to give the window a finished look. You can use wood or vinyl trim to frame the window. Cut the trim to the appropriate length and attach it to the frame using a nail gun or screws. Make sure the trim is flush with the window and the frame.

Maintenance and Care

Proper maintenance and care of your glass block windows will ensure they last for years to come. Here are some tips on how to maintain and care for your windows:

Cleaning the glass block windows

Cleaning your glass block windows is essential to keep them looking new. Use a non-abrasive cleaner and a soft cloth to clean the glass. You can also use a squeegee to remove any excess water. Avoid using harsh chemicals or abrasive materials that can damage the glass.

Repairing damaged blocks

If you notice any damaged blocks, it’s important to repair them as soon as possible. Use a chisel and hammer to remove the damaged block and replace it with a new one. Make sure to apply enough mortar to hold the new block in place.

Maintaining the frame

Inspect the frame regularly for any signs of damage or wear. If you notice any cracks or damage, repair or replace the frame immediately. Also, check the caulking around the edges of the frame and reapply as needed.

By following these maintenance and care tips, you can ensure your glass block windows look great and function correctly for years to come.