Contact Us
Blog Brochure


Preparation of the opening

The perimeter opening dimensions (width by height) should be checked in conjunction with precast production drawings to confirm they are correct and within tolerance. 

Panels are delivered on pallets. Before cutting the banding and prior to removing protective timber casing, it is advisable to manoeuvre the panels close to the location of installation. 

Interconnecting precast wall panels

For larger precast, panels can be manufactured to interconnect vertically or horizontally to make handling, lifting and installation possible. 

The panel is produced with the perimeter border to only two or three sides. The open edge of the panel which becomes the connecting joint is achieved by finishing the mould up against the exposed collar of the glass blocks. 


When constructing the connecting joint the sponge inserts (between the blocks) are removed so that a spacer peg can be inserted. A rod and glass block mortar is used to form the joint for either horizontally or vertically inter-connecting panels.

The position of the connecting joint is assessed specific to each project by manufacturer and is decided upon in relation to handling, logistics and health and safety. 

Interconnecting panels can be produced in 80mm glass blocks for use with two part U-channel. For 100mm-thick glass blocks or fire-rated glass blocks, interconnecting is still available, but an alternative method of restraint has to be used, such as flat steel plate or L-section.

Fixing guide for single panels using two part U-channel clamp

Take the main body (larger L section) and screw fix to form the main body of the frame. Place frame into pre-prepared opening.

Ensure that the base is level and plumb. Fix channel to jambs and head (using packers if necessary) and plumb the face and side directions.

NB: It is essential that the channel frame is not distorted or pulled out of square.

If fitting externally, mitre-cut the weather seal gasket and fix to channel. (Always place panel within the channel frame from inside the building).

Fix bitumen expansion joint on base and expansion fibre to head and jambs of channel (if not pre-done).

Screw fix to opening on markation lines at 400- 600mm centres. Use packers to avoid distortion. 

Unpack the first panel adjacent to the opening. Do not walk the panels using the mortar border. Lift base section of panel in place. Screw fix the cover plate loosely in position using clamps provided, screw fix them to temporarily support the two sides.

Fixing guide for interconnecting panels

Remove foam packing from between the joints and do the same with the bottom of connecting panel. Put spacer pegs between the joints of the panel. Lay a layer of matching mortar, deep enough to allow for compression.

Place 1 number horizontal reinforcement bar (supplied), lay additional bed of mortar and place the next panel on top.

Place connecting panel on top and support as previously. 

When the mortar is dry, snap off the front butterfly of the spacer and grout over the interconnecting joints. Using matching mortar fill all gaps in vertical joints, then dilute a little as a finishing grout. Be careful not to bridge the expansion material. As building commences it is important that retaining clamps are used to restrain the panel(s). 

Wipe clean faces of glass blocks ensuring abrasive materials or acidic solutions are not used.

Finishing and clamping the panels

Fit secondary L-section (cover plate) to top and base, remove clamps from one side of panel and fit cover plate. Remove remaining clamps from the opposite side and fit last cover plate.

When fixing cover plates tighten bolts loosely, then insert weather seal gasket before tightening bolts. If installing externally weather seal gasket should be used on both sides of the panel. In between the channel and perimeter opening seal the surround with external grade silicone to both elevations, internally and externally (as in the UPVC glazing industry). 

(It is important when using a standard cordless drill to use a maximum torque setting of 2).

Fix cover plate screw caps to conceal the screw heads.



news item Precast Concrete Glass Block Wall Panels

Latest Information

news item Our Process Explained - Stage 2news item Our Process Explained - Stage 1news item GBT launches U GLASSnews item Transparent Concrete Walls news item Sunderland Train Station

View all News