How to Replace a House Window

Measure the size of the glass window. Knowing the measurements will help you purchase the right-sized window.

Remove shutters from the outside if there are any. From the inside of the window remove the trim and framing. You will need to use a utility knife to cut the paint and caulking.

Lift the window out by lifting the bottom first and bringing inside. Check the wood around the frame and sill to make sure everything is in good condition. You may have to make some repairs if the wood is rotted out before replacing the window. Check to see if the new window fits accurately before placing it.

Check corners of window area to make sure they are accurately squared and that the sill is level. Apply sealant to the corners and at the sill. Then fit the window from bottom to the top.

Replace the window. One person should be outside and another person should be inside to do this accurately. Place a nail into one of the window's flanges on the outside of the window. Check to see if it is level and install shims if needed. This would go on the bottom of the window if it needs to be leveled. Place another nail into the flange on the opposite side of the window. These flanges will be attached to the sides of the window.

Nail the rest of the window by its flanges. This will hold the window in place. Use silicone sealant along the frame of the window which will help keep water out. Then place caulking where any cracks may be visible. Replace shutters on the outside of the window if you had them before.