Q–I am intrigued with glass block. I would like to install this material as my basement windows, a bathroom window and a room partition. Do you think an average homeowner can successfully tackle projects like this? How can I obtain the highest level of security for ground-level windows? Can you offer any installation tips?
A–I share your fascination with these unique building blocks. Glass block products seem to be a timeless building material. I have installed glass block windows in 100-year-old houses with little harm to the aesthetics. To date, I have not heard a complaint from my past customers concerning their usefulness, utility or durability.
I know that you will be able to handle the basement windows with little or no assistance. Depending upon the type of glass block window you choose, you may be able to do the bathroom window as well. The room partition, however, is a job for a professional.
My guess is that you might actually use a combination of materials for your upcoming projects. Traditional glass block may be the best choice for your basement window project. You can purchase solid glass block that are extremely difficult to shatter. Some will stop bullets fired from .357 magnum pistols!
Your bathroom window may be an excellent location for the clear or tinted lightweight acrylic block. You can buy acrylic glass block windows that actually open and close. These will allow you to get plenty of air into a bathroom–a perpetual haven of mold and mildew. The acrylic blocks are available clear or tinted peach, rose or blue.
The room partition may end up being constructed with thin glass block or lightweight acrylic blocks to minimize the weight on your floor. The acrylic block can be ordered in widths and heights of up to 9 1/2 feet in either direction. Traditional glass block will allow you to build large sized partitions as long as your mason installs the necessary hidden reinforcement steel.
Installing glass block panels in a basement window is very simple. The trick is to remove the old window and frame. Many cities and towns have fabrication shops that will make the glass block windows for you. You can specify the style of block and order it with little windows, dryer vents, combustion air inlets and other accessories built right into the block window. Your task is to simply install the entire unit at once.
Once you have got your new basement windows on site, check to make sure they will fit. A half-inch gap between the glass block window and frame is preferred. There is nothing worse than tearing out an existing window only to find out your new window will not work. To complete the installation, you will need a bundle of wood shims, a small level, cement mortar, a small trowel and a sponge.
Place two half-inch shims about 3 inches in from the bottom corners on the bottom ledge of the opening. Apply your mortar mix to the bottom of the window ledge. Don’t cover the shims with mortar. Tilt the window into position. Insert two shims between the top of the window and the opening. Tap them until they are slightly snug. Use the level to make sure the window is plumb. Check to make sure the gap around the window is uniform and that the window is not twisted in the opening.
Once you are satisfied with the position of the window, install the cement mortar around the sides of the window and the foundation. Once the mortar hardens–in about 2 hours–you should be able to gently remove the shims without disturbing the mortar or the window. Install mortar in the bottom holes. The top gap should be filled with foam expansion material and silicone caulk. Wipe the glass block with a damp sponge to remove mortar smears.
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Have questions about the remodeling process? Write to Tim Carter, c/o The Chicago Tribune, P.O. Box 36352, Cincinnati, Ohio 45236-0352. Questions will be answered only in the column.
For detailed instructions on installing glass and acrylic block windows, design suggestions and a list of manufacturers, send $2 and your name and address to Tim Carter at the above address. Ask for Builder Bulletin No. 184.
You can obtain a free order form for a wide variety of individual job bid sheets and other available Builder Bulletins by sending a business-size, stamped, self-addressed envelope to the same address.
Ask the Contractor can also be accessed via the Internet at http://www.chicago.tribune.com/homes/articles/askcon.
