When detailing opening sizes, the minimum opening can be calculated using this simple formula :

The dimension of the block + the width of the joint x the number of glass blocks + one more joint = minimum opening size.

*The expansion material is incorporated into this measurement. The red line around the perimeter edge of the panel indicates this & is a 10mm joint. Other spacer peg sizes are available - See: Spacer pegs.

These working formulae will vary if you are using U channels, different size blocks or different size joints or the panel is curved. For assistance contact Glass Block Technology.