Basement Metal Window Frame Replacement

In many areas of the country homes are built with basements. The windows in those basements are set into a metal frame which in turn is set in the concrete foundation. These windows are surrounded by a metal window well on the outside. As time passes these frames begin to rust and deteriorate to a point where they leak water or the window will not function properly. This can also cause a major safety concern as these windows are often the only way to escape in the event of a fire or other disaster when the stairway is blocked. In this article I will show you a permanent attractive solution to solve this problem.

The solution is actually pretty easy, however the material selection has always been the sticking point; but not anymore. Enter Azek wood products and their solid plastic line of dimensional lumber. Azek wood is approved for contact to concrete, below grade applications, as well as wet conditions. There isn’t any off gassing problem like conventional treated lumber and it’s extremely easy to work with, and it’s readily available at most home improvement stores like Home Depot, Menards and Lowes.

Azek wood takes care of the frame, now we need a window solution. Replacement windows work well in this application and are available in custom sizes from many sources. I particularly like ABC Supply and their Vinyl Max Radiance line of windows. Keeping in mind that this window needs to serve as an escape window I would suggest using a side to side slider type window as they can be removed quickly and easily. This window also operates smoothly and you don’t need a lot of strength to remove the window.

The first step in the actual project is to measure the inner most part of the existing metal frame and make your shopping list of the appropriate widths and lengths of Azek lumber that will make up the frame. When measuring for the thickness, (depth) remember you don’t have to extend the new frame to the face of the existing drywall, rather just past the existing metal frame you are covering. If you cannot find Azek wood wide enough you can edge join it, using their specified glue. You can also choose to use a biscuit joiner if you desire. Measure the width in 3 places and the height in 3 places. Using the smallest measurement determine the width and height, then subtract ¼ “ and build your square frame to the thickness (depth) you determined previously. Azek wood has recommended screws and glue that you should use when joining their product.

After your square frame is built you are going to build a “picture frame” on one face of it. Using their 3” wide product, overhang the outside by 1 3/4” (you can overhang more, but watch available clearances) and overhang the inside edge by ½”. The overhang on the inside will serve as a backstop for the window unit. If you are having trouble visualizing this, think about the casing (trim) on any door or window in your home. You can miter the corners or square cut them, wherever your skill level is. You can attach each piece as you go, or you can build it as a separate unit and attach it as one unit.

Once this step is complete you are ready to dry fit the assembled unit into the opening. Remove the existing window and lower the new frame into the window well and slide it into the opening. You may have to work from the inside and/or have an assistant to help set it into the existing metal frame.

Measuring for the window is the next step. Measure the inside, again in 3 places for the width and 3 places for the height. This will give you the outside window dimension you will need to order. Do not subtract from the measurement until you speak to your window dealer, as they will help you with the tolerance.

I recommend you install the frames now and put a piece of plywood in the opening temporarily rather than waiting until you have received the windows. Just be aware that if you use plywood you will most likely lose the ability to exit quickly in the event of an emergency.

Once you are ready to install the frames, place a heavy bead of clear silicone (100% pure silicone, not acrylic) on the inside of the outside overhang frame and slide it into the opening.  One advantage to installing the frames ahead of the windows is you can give the silicone time to set. To secure the frame you may need to install a TapCon type screw into the foundation on either side.  When your frame is set run a liberal bead of silicone around the joint between the foundation and the new frame, remembering pure silicone is not paintable. If you do not use Tapcon screws you will have to wait until the silicone has cured overnight before continuing.

Have a piece of plywood precut to fill in the opening until the silicone adheres. After the silicone has set you can dry fit the window into the frame. If it fits snugly remove it and place a bead of silicone against the stop and re-insert the window. To further secure the window rip several inside stops from the Azek wood product. These stops should hide the gap between the frame and the midpoint of the edge of the actual window frame. They should be about ½” to 1” wide. You can use a router to give them a slight round over on the exposed corner to give it a nice finish. If you were lucky enough to start with a square frame then you may not even need these stops, simply apply a bead of caulk in the joint.

You will need to install stops from the outer most edge of the new frame you made to the drywall or existing metal frame. Just measure the width of the gap and follow the steps outlined above.

There you have it, a very permanent and attractive solution to a problem that has needed a quality solution for a long time. For an easy solution to another problem read my article on custom window well covers.


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