Calculating the opening size accurately is essential be glass blocks should not be cut like masonry bricks or tiles.

The diagram demonstrates the principle of how to calculate an opening size based on using 190x190x80mm glass blocks and 4mm joints.

The Easifix extrusion is designed to create glass block panels with a minimum joint width. The perimeter joint will be approximately 5mm and the diagram and photographical step by step guide shows the use of easifix sleeve, which is 22mm deep.

Calculating opening sizes (Horizontal dimension)

• Take the width of the block (eg. 190mm)
• Add the width of the vertical spacer joint (4mm)
• Multiply by the number of blocks in the horizontal course (eg 4 No.)
• Add one more joint width (6mm) as for 4 blocks you will have 5 joints
• The final joint dimension is 6mm. This allows for 5mm at vertical end (4mm spacer and 1mm anchor bracket).The remaining 1mm (anchor bracket) to be added to the opposite vertical Easifix joint of 4mm.

Calculating opening sizes (Vertical dimension)

• Take the width of the block (eg. 190mm)
• Add the width of the horizontal spacer joint (4mm)
• Multiply by the number of blocks in the vertical course (eg 3 No.)
• Add one more joint width (6mm) as for 3 blocks you will have 4 joints 
• The final joint dimension is 6mm. In the case of the vertical height, no anchor brackets are used. The 6mm allows a slight tolerance to allow easier positioning of the top horizontal row of glass blocks.