Expansion Strip

Expansion Joints are used in mortar glass block installations to allow the glass block window to expand and contract without damaging the block.

  • 3/8″ thick
  • Placed on the top and sides of glass block installation to protect the block from expansion and contraction of the structure
  • Developed from white polyethylene foam material
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If you are doing a mortar installation of your glass block on a load bearing wall, an expansion strip, also known as an expansion joint, is necessary for restriction and contraction. Expansion strips are approximately 3/8" thick and are sold in 16 " lengths. They are used during the construction of a glass block wall along the tops and sides of the installation to accommodate movement of the glass block.

How to install Expansion Strips

Expansion Strip InstallationTo begin, first use a pair of scissors or a utility knife to trim the expansion strip for length based on the distance between the panel anchors. (Note: Trim the expansion strip width to 2-1/8" for 3-in Series block if necessary.)

Second, after applying your mortar bed, placing a spacer and embedding your first glass block, slip a 16" long piece of trimmed expansion strip between the block and the jamb and push the block firmly into place.

Third, continue to install expansion strips along the jamb as you continue to build up, checking periodically that your panel remains level.

Last, install the expansion strips across the top of the opening as you complete the installation.

how to install expansion strip across top

Additional information

Weight 1 lbs
Dimensions 16 × 4 in

3 Inch, 4 Inch


Glass Block Warehouse, Inc

One Stop Shop for Glass Block
542 Main Street
Westbury, NY 11590
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