Frequently Asked Questions - General Glass Block Questions

  What is the actual versus nominal size of Thinline™ and Premiere Series Glass Block?

Thinline™ Series block which is often called 3" block has an actual thickness of 3-1/8". Actual width and height dimensions are ¼ " undersized to allow for application of mortar or silicone. Example: 8"x8"x3" nominal equals 7-3/4" x 7-3/4" x 3-1/8".

Premiere Series block (4" nominal thickness) has an actual thickness of 3-7/8". Like the Thinline™ Series, actual width and height are ¼" undersized. Example: 6"x8"x4" nominal equals 5-3/4" x 7-3/4" x 3-7/8".

What are other differences between the Thinline™ Series and Premiere Series glass block?

Premiere Series

  • 4" thickness (nominal) provides extra stability and durability
  • Greatest selection of patterns, sizes, and finishing units
  • Highest insulation, sound transmission and fire resistance ratings
  • Recommended for curved and shower walls
  • Suitable for interior walls up to 250 square feet and exterior walls up to 144 square feet using the Mortar II installation method
  • Cannot be installed using KWiK'N EZ® Rigid Track Silicone System - must use mortar
Thinline™ Series
  • 3" thick (nominal) block is a popular residential series
  • Only finishing unit available for Thinline™ is 4"x8" EndBlock (Decora Pattern)
  • Economical
  • Ideal for windows and non-curved walls
  • Mortar II Installation: Interior panels up to 150 square feet and exterior panels up to 85 square feet
  • KWiK'N EZ® Rigid Track: Interior panels up to 85 square feet and exterior panels up to 25 square feet.
Can I use Premiere Finishing Units like Hedron, Tridron, Encurve or 8" x 8"x 4" EndBlock with Thinline™ Series glass block?

This is generally not recommended; the excess difference in thickness of ¾ " is noticeable and unsightly.

Is glass block load-bearing?

Glass Block is a non-load bearing material. Provisions (i.e., lintels) at the head should be provided to accommodate the support of loads above the glass block panel (similar to doors and windows).

What is the R-value of glass block?

The R-value for Premiere Series glass block is 1.96, which is more than twice the value for flat 1/8" sheet glass windows or roughly equivalent to a double pane thermal window. The Thinline™ Series R-values are slightly lower at 1.75.

What is the warranty for glass block?

Limited five-year warranty against manufacturing defects and loss of insulating value. Contact Pittsburgh Corning for details.