Rods & Mortar System Overview

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The Mortar system is the traditional 'wet mix' building method which can be used to install almost any type of glass block panel or feature, indoors and out, straight or curved. It is ideal for internal partition walls, shower walls and window fill-ins.

Panel anchors are used to tie the glass blocks to the frame and the use of specially designed plastic spacers ensures the correct positioning of the glass blocks in the panel. Additional reinforcement bars can be used to provide additional stability.

A specially modified glass block mortar delivers a permanent fixture and the visible joints are then grouted in a diluted mix of the mortar to give them a white finish.


  • Always cover surrounding surfaces to avoid impact damage during construction
  • For strength, glass blocks should be installed into a four sided pre-prepared opening which can be made from wood, brick, steel, concrete or blockwork
  • Openings must be square and perpendicular and made to suit the glass block modules being used
  • The most easily available and commonly used size of block is 190 x 190 x 80mm
  • To calculate height and width of finished wall, add 10mm for each block plus 10mm to overall dimension, e.g, Panel of 5 blocks wide = 5 x (190 + 10) + 10 = 1010mm.
  • Glass blocks cannot be cut like masonry bricks or tiles
  • Only use the specially modified glass block mortar when installing glass block structures
  • Only mix enough mortar to pay two courses at a time
  • Although your plastic spacers will help to ‘line up’ and ‘level’ your blocks, you should occasionally use a spirit level to ensure your panel is correctly aligned
  • After approximately 4 courses, rake out all joints to a depth of 5mm or so and clean the glass blocks with a damp cloth to remove any residual mortar. Allow mortar to 'go off' before proceeding with further courses.
  • Glass blocks will expand and contract in response to temperature changes
  • Expansion material must be incorporated into the perimeter opening
  • Maximum panel size without intermediate slip joint is 25m² with no single dimension exceeding 6m in any direction
  • If the surrounding temperature is 5°C and falling or 30°C and rising the mortar system should not be used to install glass block features.

Tools required

  • Trowel
  • Level
  • Drill
  • Screwdriver
  • Cleaning rags
  • Mixing bucket
  • Plumb line

Component Schedule

  • Glass Blocks
  • Glass block mortar - specially modified mortar
  • Plastic spacers - specifically made 10 mm thick spacers
  • Panel grout - F 15 wide joint panel grout
  • Reinforcing bars - 8 mm diameter bars ( threaded for added grip )
  • Panel anchors - specialised frame anchor with de-bonding sleeve
  • Compression foam - polythene foam for abutment to brickwork
  • Glass end tiles - for finishing off glass block ends

These instructions are for guidance only. They are not intended to imply suitability for any purpose.
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