How to Replace and Trim Out a Basement Window (DIY Window Removal, Replacement, and Trim Install)

Learn how to Replace and Trim Out a Basement Window with this DIY step-by-step guide. For my basement windows, I used the "drywall return" method.

To replace and trim out a Basement Window, you will need to follow these basic steps:
1. Purchase Replacement Window(s)
The first step in replacing basement windows is to order your replacement window(s). To do this, measure the rough opening of you concrete foundation window penetration and compare those dimensions to available replacement window dimensions. There are many different sizes and styles of windows, so spend sufficient time ensuring that the replacement window you purchase will fit within your existing window penetration.

2. Remove the Existing Window
The second step in replacing a basement window is to remove the existing window. Start by removing any screws or nails that are holding the window in place. Then, remove the glass panels (if possible). Next, use a reciprocating saw to cut the top of the window frame and then try to loosen the frame from the concrete it is embedded within. If the window is stuck, use a pry bar to carefully loosen it from the home's foundation.

3. Position The New Window in Place
Position the replacement window into the opening and center it as best as possible. Use shims to hold the window in place.

4. Level the Window and Install Shims
To ensure the replacement window is level, use a carpenter's level to check for any unevenness. Use shims to make any necessary adjustments to the window's level, placing them in the gap between the window and the rough opening.

5. Apply Spray Foam around the Perimeter of the Window
Once the window is in place, secured with shims, and level, apply spray foam insulation around the perimeter of the window. The spray foam will help seal any gaps and improve the energy efficiency of your home. Be sure to follow the instructions on the spray foam can and wear gloves and protective eyewear during this step.

6. Cut off Excess Spray Foam and Caulk Around Window
After the spray foam has dried, use a utility knife to cut off any excess foam that is sticking out. Then, apply caulk around the exterior of the window to seal any remaining gaps. This will help prevent air and water from entering your basement. If you have a damaged any of the concrete around your window, you can repair it with rapid setting concrete and trowel at this stage of the project.

7. Trim out the Basement Window.
To install drywall a drywall return around a basement window, start by cutting drywall for the top and sides of the window. Cut they drywall such that it contacts the window’s frame on one side and so that it is flush with the wall drywall on the other side. Then, install corner bead and finish the drywall with joint compound. Caulk any joints between the drywall and window.

8. Install the Window Sill.
To cut your own window sill for a basement window, select a piece of lumber that is approximately 1.5″ wider than the depth of the basement window cavity. You may need to “rip” the lumber to a suitable width using a table or circular saw. Cut the off the sill so that it is 3″ longer than the window cavity on both sides. Next, use a router to give the window sill a rounded edge and use a jigsaw to cut the penetrations on both sides of the window sill – leaving a 3″ overhang on each side. Finally, caulk any gaps and paint the window sill (if desired)

This video will outline every single step outlined above - in detail.

This Basement Window Replacement and Trim out Project is part of my basement finishing series. See additional videos below:

Episode 1: How to Install Rigid Foam Insulation

Episode 2: How to Frame Basement Walls

Episode 3: How to run electrical in a basement

Episode 4: How to Frame around HVAC and Pipes in a basement

Episode 5: How to Drywall a Basement

Episode 6: How to install LVP flooring in a basement

Episode 7: How to Install a Drop Ceiling

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Thank you so much for watching!

*All content on the Andrew Thron Improvements YouTube channel reflects my own opinions. Please seek out guidance of professionally trained and licensed individuals before making any decisions. Links in the description may be affiliate links.

[cadayx]

Just finished installing two of these TAFCO basement windows from homedepot. Pretty straight forward. Made a few amateur mistakes. But you live and you learn! Thanks for this great video!

[johnstup]

Nicely done! I recently finished a wall in the basement and I boxed in the entire window in 1/4" birch plywood and added trim molding around the box and painted white. The only thing that I would have done additional on your window would have been to smooth out the caulk on the outside.

[curranlipsett]

I finished a basement in a rental about a year ago and the windows were by far the most confusing part! I also did the cheap drywall finish but it turned out pretty good. I didn’t swap the window, but after seeing this video I think I well sometime soon!

Nice job showing those tricky things like how to remove the window flange and how you attached it to the building. I’m not too surprised foam/caulk plus the concrete on the outside is enough to keep it stable!

[Hapesnova]

It is a crime you don't have more likes for this. Great stuff man. Helped me out perfectly.

[dangamache]

Love all your video's Andrew! Ive learned alot and will use what ive learned when I finish my basement.

[wtpnjjt]

Looks good, but rule of thumb is to use a material that can withstand the high temperature differences between the window/wall to prevent future mold growth from condensation. Drywall will not stand the test of time.

[weekendhomeprojects]

Awesome job! Huge transformation. I like it.

[PankDotOwner]

Thanks! Great instructions. Going to try but I’ll start w just one 😊

[sebastianogrossi]

Is flashing not necessary in basement windows? Our windows are installed the same way as your video and I’m worried about water infiltration because there isn’t any flashing or sill tape.

[VampireOnline]

Why didn’t you smooth out the caulk on the outside?

[lanejohnson]

Great videos as I'm finishing our basement now. I contractor friend told me that I need to frame in the concrete opening with PT and then attach the window to that. Is that not needed or maybe could it be a city or state code requirement? I like your way because I can get a little bigger window in the opening. Thanks!

[GeneralChangFromDanang]

I don't understand why Tafco went so small on their nailing flanges. Totally screwed me over on my garage installation.

[bjf]

Wait, how did you actually secure the window in place? With the spray foam?

[tompopowich]

How do you open the window without removing the blinds? Just curious if it’s possible

[briandimascio]

I did this about a month ago. I wanted to do the sliding windows but went w these just bc they let in more light without having a frame around the sliding glass frame

[SergioMarcyKiaraAJ]

where did you buy the window? I am not having luck finding where I can purchase

[grouchostarx]

Lol, “snugly” is, in fact, a word. (No hyphen. 😉)

[Kathy]

Hi, your video content is very expressive, I would like to sponsor a smart sprinkler controller for your lawn, are you interested?