If your old cast-in-place and steel-framed basement windows are starting to show signs of corrosion, or if the single pane of glass and lack of gaskets mean leaks and drafts, it may be time for a replacement.
Basement Window Replacement
Step 1: Remove the Existing Window
Before you begin any work, make sure you have a safe place to set the window down. Lay a drop cloth on the floor below and remove the window from its opening. Be cautious not to damage the sill of your old basement window as it will be reused for your new one.
Step 2: Prepare New Frame
Measure measurements for new frame at local home improvement store or lumberyard, then cut wood pieces according to those measurements using table saw or circular saw. Be sure that all inside dimensions are slightly smaller than interior of existing window frames, so that they can rest snugly within them when installed. Cut several blocks of similar size with which to shim gaps between windowsill and window, once window is installed.
Step 3: Install Frame
Fit new frame into opening for it, first laying wood pieces against the outside of the existing window sill and checking them for fit to be sure they are slightly smaller than inside dimensions of your existing window. When you are satisfied with the fit, nail each piece in place with 16d nails through the exterior cladding of your home.
Remove any excess nails so as not to protrude beyond surface of trimmer board and cause injury or damage to anyone who may come in contact with trimmers later on during project. Continue this process until all pieces of frame have been secured in place. TIP: If there was no window sill before – install one now using cedar shims and silicone caulk to seal any gaps between wood and concrete wall.
Step 4: Add Flashing
Lay an ice guard system along each side of the window frame, taking care to caulk all seams so that no moisture can get in behind it. Fit flashing strips over the ice guard systems, again sealing off all spaces where water might get in with caulk. You may also want to add foam insulation under-neat flashing area to help prevent heat loss through basement windows.
Step 5: Install Replacement Window
Place replacement window into its opening and shim it until it is level & plumb (vertically straight) using the blocks you cut earlier. Nail flange boards around top, bottom and sides of your new basement window using 1 1/4″ brad nails. TIP: Some windows come with snap-in flange boards that may go around frame of window if they don’t fit tightly against the frame already. Contact your new window supplier for more information on this subject if unsure about your product.
Step 6: Caulk Window Flanges
After you have installed all the flange boards around your window, caulk them to fill in any seams left between pieces and seal up any spaces along the exterior where water vapor might be able to get through basement windows, causing mold or mildew growth.
Step 7: Cut Screen Frame & Fit Screen
Cut a piece of mesh screen an inch larger than size of opening. You can purchase a roll of screen mesh at any home improvement store or lumberyard, then lay window screen flat on top of your new basement replacement window opening. Use a marker to mark the outside dimension of your replacement window flange boards onto the screen using a ruler and straight edge.
Lift up mesh so that it rests along trimmers, but does not block the center grille area over your replacement window. Cut out this piece with heavy scissors or tin snips where you’ve marked it onto screen mesh. Afterwards, measure height and width of opening again to be sure that the screen has fit properly according to measurements you have taken at local hardware store before cutting.
Step 8: Fit Screen Frame & Secure in Place
Fold back half of mesh covering one side of your window and slip the window screening frame (narrow-side in) over this half of trimmer. Secure in place with hinges, then do the same on other side using remaining piece of screen frame. TIP: You can also purchase a roll or pre-made mesh screens that come ready to fit around your basement replacement windows.
Step 9: Fit & Install Grille
Finally, cut grille section out of mesh and attach it to center grid above your replacement window either with hinges or small screws. Now you’re all done! Enjoy your freshly installed basement window without worrying about snow build-up on its sill, ice damming near the edges during winter months or water seeping into your home via top gap between window flange boards.
Basement Window Replacement Cost/Materials
$22.00 to $27.00 / linear ft. for wood flange boards depending on brand and quality of cedar used. $5.75 / linear ft. for ice guard systems at local lumberyard or home improvement store, plus caulking if needed ($2.50 ea.) $.95 / roll for window mesh screen as needed (cut as instructed above) $.25 / small lid of silicone caulk as needed ($3-6 per tube, depending on brand)
NOTE: You may need other materials such as shims, hinges, screws etc., if you’re trying to fasten special frame pieces around your replacement window and should take into consideration any other tools like saws, basic power tools like drill and jigsaw etc. depending on whether you’re doing this project yourself or hiring a contractor to do it for you.
How to replace a basement window – Time?
- 1 person-8 hours;
- 2 people-4 hours;
- 3+ people-2 hours
This is just an estimate based on work factors including but not limited to material accessibility, skill level required or how much time is needed per person given weather conditions at the time of installation. We’ve included factors such as what can happen if shims are misplaced or nails aren’t hammered into surface evenly/strong enough etc., so be sure to have someone help you or oversee your work if you’re a novice at this type of project.
Basement window replacement cost – general
Be sure to have an adequate budget for materials & installation estimates before beginning any DIY basement window replacement projects, as prices can vary from region to region and depending on the needed tools and sizes of replacement windows needed for each space. Additionally, you may want to shop around at home improvement stores for additional discounts on special lumberyard days or during promotions that offer coupons or daily deals (some run sales/promotions that include free shipping).