Posted by: glassblockblogger | February 25, 2012

Installing a Glass Block Basement Window

Glass Block Basement Window Installation
New York, New Jersey, Boston, Philadelphia

Previously we discussed the basement window being The Most Vulnerable Part of the House to FloodingA response to this concern is a Window that has the characteristics of a solid concrete block wall, such as a glass block window.Basement Window Eastern Glass Block

So let’s cover the steps necessary to install a glass block window in a basement made from concrete or concrete block. (Installing in a wood-frame has some additional considerations that will not be covered here. But, call us if you have that situation.)

Glass Block windows are available pre-assembled. You can choose standard or custom sizes, with or without ventilation. In general terms, you just set the panel in place and pack mortar around it.


You will need tools that may not be a standard in your toolbox, like a masonry chisel and select trowels. But these are easily found in any hardware store and will come in handy during a future project around the house.

Remove the Old Window

First, you need to remove the old window. Use a crowbar to pry out the old window jamb. You may need to cut the wood sill with a handsaw or circular saw. Use a chisel or utility knife to displace whatever was holding in the old window jamb. At this point, you just need to get tough without causing structural damage. The objective is to completely get out the window sill, the side jambs, and the head jamb.

Set the New Window in Place

Next, you need to prepare to set the window panel. Before you set the panel in the rough opening, you need to attach a temporary block to keep the panel from falling through the opening while you mortar it in place. Screw a wood block to the underside of the sill plate, or to a joist if there is not a sill plate. The temporary block should be set far enough in that you will have the window recessed to the depth of your choice.

Now you are ready to set the panel in the rough opening. Make sure to sweep the rough opening clean before you set the panel in place.

You will need to have at least three wedges to temporarily raise up the panel when you set it in the opening. Make sure that the wedges are greater than the thickness you will need and that they are long enough that you can grab onto them when it is time for them to be removed.

Glass Block providing security and beauty to basement windowMortar the New Window in Place

The last step is to pack the mortar. Pack and smooth the mortar at the bottom first. Be careful to not mortar in the wedges. Wait until the mortar has hardened somewhat along the bottom before you mortar the sides. Remove the wedges. Fill in all the gaps and smooth the mortar for a finished look. Brush away all mortar crumbs. Make sure that all gaps are filled in on the inside. You may want to have the mortar flush on the inside to accommodate a window sill, whereas the outside can be sloped for strong support.

We Install

Give us a call at Eastern Glass Block. We would be pleased to answer any of your installation questions. We have over 20 years of experience designing and installing commercial and residential Glass Block nationwide and would love to hear from you.


  1. […] Installing a Glass Block Basement Window […]

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