How to Install a Window

Check Building Codes

Not all window types can be installed into every wall. For example, tempered glass may be best for windows that are closer to the floor, and installations where the sill is higher than 35 feet above ground level must be designed by an architect or structural engineer. It is best to know which window you’ll need for your application.

Safety & Handling

Read and fully understand all manufacturers’ instructions before beginning. Work with a partner to lessen any chance of damage to the window, or worse, to yourself.

Tools Needed

A good utility knife, hammer, tape measure, caulking gun, power stapler (minimum of a 4’ level), and a drill motor with bits will complete most jobs.

Materials Used

Follow all instructions carefully, but most replacements will require the following materials:

  • galvanized roofing nails
  • housewrap such as Tyvek
  • backer rod (foam shaped in a roll to fill gaps before caulking — different diameters available)
  • low-expansion foam or fiberglass insulation
  • shims
  • caulk
  • approved window tape or flashing to seal off any water infiltration

Inspect the Rough Opening

Verify that the width and height of the opening is 1/2” to 5/8” larger than the window itself to allow for shimming. Then, verify that the opening is square, plumb, and that there is no sagging. Consult a licensed carpenter if there are any concerns. This may prevent an unneeded replacement down the road due to stress cracks.

Housewraps & Window Tapes

Understand how housewrap and window tapes work and how to properly install them. The most expensive window and flashing will work just as well as the least expensive if not properly installed.


After installing the proper flashing materials, unpack the window right-side up to prevent any damage in case windows or patio doors were shipped unlocked.


Place window into opening, shim, fasten, check for proper operation, and apply the water barrier or flashing to complete installation.

Let Us Help

Fisher Lumber Showroom and Fisher Lumber are your one-stop destinations for new or replacement windows. We offer installation by licensed contractors, and we can fit every need for every budget. Call us today!

hear from our customers

“Thanks again for all your good help. Everyone was very talented and professional that we had in our home.”
— Sherrill