A new window can provide better light, better views, and increased efficiency to a home. Better light and views are related because most windows that are replaced have moisture or fogging between the panes causing poor visibility and obstructing the light coming through the window. However, one of the most frequent comments I receive after replacing windows is about how much quieter the home or a room is with the new windows.

Steps to successfully replace a window in your home.


Replacing a window can be a tedious process but a properly replaced window can make a big difference in your home. Measure, measure, measure, and measure one more time, like the old saying “measure twice, cut once.” In the case of getting the proper size replacement window the measurement is crucial. I start by measuring the window from the inside of the home. I measure from the finished opening that window sits in, extension jamb to extension jamb. Most wood jamb materials are ¾ of an inch thick so add 1.5 inches and that is your rough opening for the window to sit in. If the sills are wrapped in sheetrock, the rough opening is only 1 inch larger from jamb to jamb. Window dealers only need the rough opening because the window will be cut ½ smaller than the rough opening. I also measure bottom, middle, and top and use the smallest measurement. After I am sure I measured correctly on the inside of the house, I will also go to the outside and measure. Most windows will have some sort of moulding. I will measure the exterior of the window similar to the way I measured the interior.


Now it is time to determine whether to use the same type of window including casement, single or double hung, picture, or horizontal slider. Keep in mind some building codes for windows such as egress for bedrooms and tempering windows in hazardous locations like stairways, shower stalls and bathtubs, or within a certain distance from door.


Once the window has been delivered to the site it is time to replace it, but first the old window must be removed. Pull off all the exterior moulding and interior moulding to expose the edges of the window. Before removing the window check the size of the new window to make sure that it will fit. Remove any nails or screws holding the old window in place and be careful not to break any glass for safety. After the window has been removed, check the sill for any rot. Replace any wood in the framing that is rotted. Finding rot may involve removing some siding to properly remove all of it.


After the rough opening has been cleaned up, it is time to wrap the window with and ice and water shield. Start at the bottom of the sill and work your way to the top, this will ensure that all your joints in the ice and water shield will be lapped properly. At the head or top of the window make sure that your ice and water shield is tucked under your house wrap to ensure proper flashing. Just like a fisherman wouldn’t tuck his raincoat into his pants, make sure that your flashing is tucked into the house wrap so that any water getting through the siding does not run behind the flashing. Another key is the make sure the ice and water seal adheres to the vapor barrier that should barely be visible around the rough opening between the sheetrock and framing members. The process of securing the ice and water shield to the vapor barrier can dramatically help with improving energy efficiency.  When finished, the rough opening should be completely wrapped with the ice and water shield.


Now that everything is flashed properly follow the manufactures instructions on window installment. Most windows have a nail flange used to fasten the window into the rough opening. Before I place the window in the rough opening, I use a butyl tape around the flange instead of a caulk to ensure a good airtight seal that will remain flexible with the expansion and contraction of the window. Vinyl and wood or even different types of wood will expand and contract at different rates so having something that will remain flexible will ensure a good long lasting seal. Using a level, place the window and fasten it into the rough opening.


Not quite done yet. Take the same ice and water shield and flash over the nail flange, again, starting at the bottom of the window with the ice and water shield and working your way around and to the top of the window to ensure that the laps in the ice and water shield are lapped properly. Remember not to tuck you raincoat into your pants. Finish the exterior by trimming the window and then return to the inside of the home to completely finish the window.


Use low expanding spray foam to insulate around windows. It is essential to use spray foam that is made for insulating around windows because a high expanding foam can and will break the window when it expands. The window should have about a ¼ inch gap around the perimeter to insulate completely around the window. Let the foam set up and now the window can be finish trimmed on the interior.

By following these steps, you will ensure that the new window will have optimum performance for many years to come.

Greg Stopher has over 16 years of experience in the construction field and earned a degree in Construction Technologies from the University of Alaska – Southeast. His company, Stopher Construction, LLC, is a general contracting company specializing in remodeling, custom finishes, additions and new home construction projects. He can be reached at 907-321-2350.