How to Repair Block Glass Windows

October 11, 2010

Nothing spoils the look of block glass windows like a chip or crack in one of the blocks. If you're wondering how to repair block glass windows, start by gathering a few materials and setting aside an afternoon.

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How soon do you want to begin this project?

  1. Start by measuring the space and determining how many blocks are affected and need to be replaced.
  2. Go to a home improvement store to find replacement blocks, mortar mix, and a chisel and hammer. Protective eyewear and old work clothes also are a good idea.
  3. Apply heavy tape to both sides of the glass block to secure it and start chiseling it out. Once the damaged glass is removed, use the chisel and hammer to break out the old mortar. As you work, keep hands and elbows in check to avoid slipping and damaging the adjacent blocks.
  4. Once you've removed the glass and mortar, vacuum the space.
  5. Pour the mortar into a container, add water, and stir until the consistency is smooth, but not too runny.
  6. Use a trowel and add a layer of mortar to the bottom of the first opening. Put the block in place and pack mortar around the three remaining sides, making sure to follow the same mortar thickness found in the rest of the block glass windows.
  7. Let the mortar harden, which can take two or three hours. Use a narrow, spatula-type tool to smooth all the joints.
  8. When you're finished, use a wet rag to wipe off any excess mortar.

The final step is to stand back and admire your work.

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