How to Install Glass Block Windows in a Basement


The value of having windows in a basement cannot be overstated. Builders back in the day understood this. Therefore, they installed hopper windows in basements. Commonly, they were four regular cement blocks (16″ x 32″) in size. These windows often had a steel frame and were mortared into position. Unfortunately, they also have the potential to let in drafts and intruders. A beautiful and secure alternative to inefficient hoppers, prefabricated glass blocks can be fitted to let in natural light while keeping intruders out.

If you want to know if a basic pre-made glass block unit measuring 16″ x 32″ will fit, look carefully at the window in question. Find a cement block close to your working window and measure its dimensions. For quite some time, the typical cement block has been 7 3/4″ high and 15 3/4″ long. The blocks are 8 inches by 16 inches because they were designed to take up a mortar bed of 1/2 inch. Count how many bricks were moved because of the window. The correct dimensions are 16 inches wide by 32 inches long or two blocks high by two blocks long.

You can pick up a prefabricated 16″ x 32″ glass block unit at any hardware store. Purchasing a ready-made unit eliminates the hassle and inconvenience of constructing one from scratch and ensures a perfect fit because of the factory’s attention to detail. Things to keep in mind while shopping for home improvements include:

Tools and materials needed include: o Tape measure o Hammer o Cold chisel o Pry bar o Reciprocating saw with metal blade or hacksaw o Shims (composite) o Expansion foam o 1 Bag of mortar o five gals. bucket o Margin trowel o Access to water o Silicone o 4″ Glass block “C” channel (typically located in the glass block aisle) o 1 12″ screw o

A single person can accomplish this renovation; however, having a helper is highly recommended.

To prevent having to clean up dust and debris from your work area constantly, you should cut a piece of plastic to fit beneath the window opening. You might want to use more plastic to create a barrier to contain the mortar dust and chips in one section of the basement. Take out the hopper window sash and throw it away. Sash posts should be able to be pushed up and out through an enlarged aperture in the flat metal arms the belt hangs on. Repeat on the opposite side, and then haul the old window out. Next, decide whether it’s preferable to do the cold chiseling of the mortar off the steel frame inside or outside. This may involve a lot of physical labor, including the use of a heavy hammer and protective eyewear. Chisel in the center of the opening’s base and see if that helps. Get close to the metal first, then move below. Create a space under the metal structure to lift it with a pry bar. To remove the frame, first, pry it up and then use a reciprocating saw or hacksaw to cut it. Once the base has been loosened, the sides and top can be removed. The glass block unit is 16″ x 32″; thus, the hole must be chiseled to accommodate it. Mind your measurements. If there is a bump that could cause problems in the future, now is the time to get rid of it.

Now that the challenging phase is over, you may proceed with the installation. A sill plate is a board installed over an opening’s rim. Insert the “C” channel here and tighten it. If it’s too broad, the “C” channel should be pruned now. The product is made of PVC and may be easily trimmed to size with a hacksaw. The proper placement of the track requires attention. The “C” channel should be installed perpendicular to the outer wall and centered in the opening. Installation flush with the exterior wall is not always practicable. That’s fine; aim for the closest

approximation. Batt insulation was cut to fit in the “C” channel and the width of the glass block (about 4″ X 32″), and shims were stashed nearby. Two individuals must install the window to ensure the insulation remains between the “C” channel and the window. Make sure any windows in the unit are correctly installed. The locking hardware for a window should be on the inside while the screen and weeps are placed outside. Shims are used to maintain a window securely in its channel when installed. The torpedo level is currently used for all plumbing and leveling tasks. After vacuuming out the opening, fill the space on the floor and walls with expansion foam. Avoid going into overdrive. You only need a small amount because too much will make the foam ineffective. The “R” value of the foam increases as it expands, and it also aids in keeping the unit in place. Congratulations! Now that the expansion foam has been applied, you may finish cleaning up and let it set overnight.

When you return the following morning, trim the expanding foam to fit snugly against the window. Mixing the mortar with water in the five-gallon bucket can ensure peanut butter consistency. The expansion foam is placed over the cannon, and the margin trowel is used to pack the mortar around the edge of the glass block on both sides of the window. This stability is what keeps the whole thing together. If the glass block is not level with the wall, the sill must be sloped so water flows away from the unit on both sides. To perfect the mortar, some practice is required. It will comply with your wishes more readily the less you fiddle with it. In the case of “sagging” mortar, you should return when it has been set up but is still “green.” Use the trowel to shave off any surplus and level up the surface. Finally, use silicone inside and outside to create a watertight seal around the “C” channel and the sill plate.

In a day, the mortar will have set and become hard. If any mortar gets on the glass, wipe it off with a damp sponge or rag. You may now relax knowing your new glass block window is sturdy and aesthetically pleasing.

In addition, you can learn many other secrets of the trade from skilled remodelers by going to:

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