How Hard Is It to Replace Windows in a Concrete Block House?

Ripping Out the Old Windows

• Care must be taken when removing the windows in a concrete block home not to crack the concrete. Insert a pry bar between the window frame and the concrete and lever toward the window, not toward the concrete. Slide the pry bar down the frame and pry every few inches until the entire frame has popped free. Focus your attention on the concrete, not the window. Breaking an old window is a lot less serious than cracking the concrete.

Preparing the Frame for the New Window

• All of the old wood from the previous window will need to be removed before the new window can be installed. This is not a difficult process. Simply pry it up and rip it off. Once the wood is removed, you can see if any of the concrete will need to be patched underneath. Typically, there should be no cracking or depressed areas, but if the home is old, you may need to mortar around the frame to fill these areas in. You must use the exact same size window that you had before. That is the key to making the replacement process a breeze.

Installation Process

• New wood will be put into the window cavity. Masonry screws can be used to get a nice, tight fit between the wood and concrete. This will require a special masonry drill bit, but these can be purchased at any hardware store. Use a level while you work to ensure that the frame is perfectly level. If the concrete under the wood is not, you can insert wood shims to create a tighter seal.

Sealing the Window Properly

• The biggest issue with windows in a concrete block home is failing to seal them so that they are watertight. Once the window has been installed, caulk around the edges, laying down a 1/4-inch bead around the frame. Let this set for a few days. Now, take a fan outside with an extension cord and turn it on high. Have someone stand inside the home on the other side of the window. If they can feel the air through the frame, it will need more caulk. That's a very simple way to tell if you have a good seal on the window.