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How to Build an Interior Glass Block Wall (page 1 of 2)

A glass block wall can create a division between rooms without blocking light.

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Apply Mortar to End Block After Every Two Rows

Step-by-Step Instructions:

A glass block wall cannot be loadbearing, but it will be a sturdy structure, thanks to metal reinforcing rods that are positioned in the mortar. Glass blocks can also be used to build a screen across part of a room or as a shower cubicle. Do not build any higher than six courses without stopping to let mortar dry overnight, otherwise the wall may collapse.
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Plan and Prepare

Most glass blocks measure 7-1/2" x 7-1/2" x 3-1/5". They cannot be cut to size, so base your calculations on how they best fit into the space. Half-blocks and corner blocks are available. Use wooden plates to fill any gaps left between blocks and a wall or ceiling. These will be inconspicuous when painted.

Designing a Partition
Lay out a single row of blocks to judge a screen’s extent into the room. A full wall may need a doorway. Its position will depend on how blocks fit across your room. The opening will need suitable ties inserted through the door lining into the mortar. Building within a wooden frame gives clean edges, but the mortar method can be used without a frame depending on your floor surface.

The Floor Surface
Mortar can be laid directly onto a concrete floor. With a wooden floor, lay the first row of blocks on a wooden sole plate, even if you are not building in a frame.

Calculate Quantities

Multiply the length of the wall by its height to find its surface area. Divide this by the area of one block for a rough idea of the number of blocks needed, not allowing for mortar joints. Buy 10 percent extra, in case any blocks brake. White mortar (ready-mixed) is available in 27-1/2-lb. bags — enough to construct a small shower enclosure. Spacers give even joints. Allow 1-1/2 per glass block, and buy 10 percent extra. The spacer shape can be modified from X-shaped to T- or L-shaped as required.

Allow two reinforcing rods per row of blocks. Buy more if you wish to push rods into the vertical joints for extra rigidity. Sealing the partition. Use white mortar and white grout. Use waterproof grout and silicone sealant in a humid room, such as a bathroom, and use silicone sealant on the joint between the glass-block wall and the existing wall. Some manufacturers supply expansion strips for the wall’s perimeter in a humid area or one with temperature change.

Construct the Frame

Make a wooden frame to fit your chosen wall dimensions. Use lumber struts of 4 x 2 inches or 3 x 2 inches, with the same width as the blocks (image 1). Fix the frame in place at your chosen location for the wall. Remember to use a cable detector to check that it is safe to screw into the floor (images 2 and 3).

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