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Glass blocks regaining popularity
Nov 26, 2004

Some years ago, glass blocks were popular as dividers in the home where light transmission was important. Over the years they faded in importance, but now enjoying a comeback.

At one of the building stores, I checked with a salesperson on the resurgence of glass blocks. I was told that glass blocks are popular in both new and existing homes. 

In one new home I recently visited, a grand curved staircase to the second floor had one side closed in with glass blocks, adding a dramatic touch to the front living room. 

The blocks also make attractive room dividers at front door entrance ways, serving as a windbreak when the door is open, while letting in light from sidelight windows or windows in the door. 

Glass block dividers can be installed by the home do-it-yourselfer or by a masonry contractor.

A glass block wall is more difficult to install then a regular masonry wall, because it will not absorb moisture from the mortar as is the case for a masonry wall. You must use a special spacer to support the weight of the blocks until the mortar sets. Some find it best to lay only two or three rows of blocks and then let the mortar set before adding more rows of blocks. 

Glass blocks can also be used to fill in basement windows, adding a sense of security. In addition, neither curtains or blinds are required to cover the beauty of glass block windows since they are opaque and let in natural daylight. 

They can also be used as planters or in rec room bars. Coloured lights installed in the front of the bar add a dramatic touch. 

The most common sizes are six-by-six inches or eight-by-eight inches with a thickness of three or four inches. 

The blocks can be installed along the floor as long as there is no “bounce” in the floor. If the floor bounces or moves when walked upon, the floor must be shored up. This is easily done in the basement as long as the floor joists are readily accessible. If the area of the floor being shored up is above heating ducts or the basement is finished, you must remove the impediments to gain access to the floor. 

The floor joists can be strengthened by gluing and nailing two-by-fours or two-by-sixes to the side of the joist and tight to the bottom of the floor. Since an existing floor joist is usually a two-by-eight or larger, the narrower support can be manoeuvred to the side of the existing joist. 

Apply a good quality sub-floor adhesive to the top edge of the new wood as well as on the side that goes against the existing joist. Use coated box nails to nail the support to the existing joist. 

Once the bounce in the floor has been fixed, set the blocks going onto the floor with a cement mortar base.                                                                           

Put the mortar on the prepared floor and simply set the glass blocks into the fresh mortar, cleaning any mortar that has oozed out before it sets. 

Glass blocks are usually found at specialty building supply stores, which also have literature available and a display of glass blocks. 

Some homeowners may decide that working with glass blocks is quite a challenge. If that is the case, it is best to hire a professional.