I have three of these metal-framed basement windows which I would like to replace but I am unsure of what dimension I should measure and use for the replacements.

Full Window

Initially I measured the outside dimension (32 1/2" x 16 1/4") but on closer inspection, it looks like the metal is just folded up against the concrete. This leads me to think I should use the inside dimension (30 1/2" x 14").


What is the correct way to measure for replacement windows in this case?

EDIT: Included some outside pictures

Outside 1

Outside 2

Outside 3

  • It appears the metal frames are set in the foundation. In which case removal will will require extensive work. Are you willing to install replacement windows using the existing frames for the anchoring points? – mikes Sep 23 '12 at 21:20
  • They outside of the frames are not in great condition - it has been bent away from the foundation which I think is partly why the water got in. I was planning on removing them if possible (can I not use a sawzall and prybar to remove them?) – Steven Sep 23 '12 at 21:51
  • 1
    @Steven - I've removed metal frame windows in times gone by. In my case the concrete wall blocks had a grove that accepted a flange of the metal frame on the inside part of the frame. Mortar was trowled into the groove to seat / seal the frame. I had to use small chisel to break out the frame. I agree that a Sawzall with some good metal cutting blades would be a good way to get the metal frame partially free. It looks like your walls are poured concrete and the frames were probably set in place in the forms and the walls poured around them. Cutting the frame will -- continued... – Michael Karas Sep 24 '12 at 3:02
  • Continued from above - will likely allow the frame to be literally be peeled from around the opening. – Michael Karas Sep 24 '12 at 3:04
  • 1
    Sawzalls and chisels and prybars can do wonders. If you're willing to protect and live with the rough opening for a couple weeks, the best way will be to remove the window and get the rough opening ready, and then measure and order exactly what you need. Without that, you have to guess what's under the flange, and if you'll be able to cut through any metal/concrete/rebar that may be in your way. – gregmac Sep 24 '12 at 22:28

If the metal frames are rotted to the point of being unusable you can remove them. It will not be easy. They may have anchors embedded into the foundation. Until you remove the frame you can't tell what the size of the opening will be. You may also need some masonary skills to repair or prepare the opening to accept the new windows. Then you have to decide how the windows will mount to the concrete. You can frame the opening with P/T wood and then anchor the new windows to the wood or metal frames anchored to the original masonary opening. The opening may require a bit of work to set new metal windows. Another option is glass block set diectly into the opening if ventilation isn't required.

  • Glass blocks are a good option for some cases. However if the basement area is to be occupied as a living space, particularly as a permanent bedroom, there are many areas that require that there be egress windows that would allow a person to escape in the case of fire or other disaster. Glass blocks do not fit that usage model. – Michael Karas Sep 24 '12 at 3:17
  • I don't believe a 16"x32" window with a security bar qualifies as an egress point anywhere. – mikes Sep 24 '12 at 4:10
  • It will not be a living space (so I don't need egress) but there will be washroom here so I'd like for the window to open – Steven Sep 24 '12 at 14:14

Foundation windows are a difficult item to order replacements for. The mounting and track is different for most manufactures. Since you can't easily change the steel frame that is embedded in the concrete, you need the right window glass frame and size. My advise would be to remove the glass sashes and bring them with you to your supplier and see if they can identify the manufacturer. they can measure them and order the right items. The other option would be to take the glass and removable frame to a glass shop and have them reconditioned.

  • I was under the assumption I'd be able to remove the steel frame and install the window in the concrete opening - is this unlikely to be the case? – Steven Sep 23 '12 at 21:50
  • hard to tell from your pic, but most are seated before concrete is poured. have to take a closer look. A pic of the outside will be telling. If there is flanges both inside and out, then you aren't gonna get the frame out. – shirlock homes Sep 23 '12 at 22:31
  • 1
    I should also mention, nothing can't be removed with a sawzall and some perseverance . then measure the opening in the concrete and order an insert window and seal it in well. – shirlock homes Sep 23 '12 at 22:36
  • I edit the question to include some outside pics – Steven Sep 23 '12 at 23:20
  • You can get basement windows assemblies that come pre-built with the outside brick molding already installed. These simply slide into position from the outside with the molding overlapping the outside of the opening in the concrete wall. You can set these into the concrete after size and fit checks with some construction adhesive. If there is a gap of more than 0.25 inches you can use shim wedges to secure the frame. Use a temporary set of shims to hold the unit in position and then apply the adhesive to the other set and wedge into place. – Michael Karas Sep 24 '12 at 3:12

I ended up completing this project by removing the metal frames first and then measuring the opening in the concrete. I had the window boarded up for several weeks which is what I was trying to avoid.

After having removed the frames and seeing how exactly they were embedded, it is clear that I could have measured inside the metal frame and added 1/8" to account for the thickness of the frame. In this case I would have had accurate measurements and avoided not having a window for a bit.


The answer to your question; windows are measured by the size of the empty opening.

  • 1
    A little more explanation of how and where exactly to measure the size of the empty opening would be useful. – ChrisF Nov 30 '12 at 12:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.