Window Installation Basics | A Step-By-Step Guide

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Window Installation Basics

We are going to take you through the window installation basics to explain what is involved in a quality install. The price range for standard installation is around $100 to $150 per opening. In addition, our replacement window calculator can also help you compare pricing for different installation techniques such as pocket or simple insert installation.

-- Price Range: $100 to $150 per opening --

Step 1: Measure The Opening

When the company comes out to give you a free cost bid, they will measure each window opening for ordering and cost estimate purposes. It should be said that properly measuring each opening is very important. There has to be enough room to add a low expanding foam to properly seal the window, but not too much that there are large gaps that need heavy amounts of insulation.

1. They will measure inside the window frame (width from jamb to jamb) across the bottom, middle and top and write down the smallest measurement.

2. They will measure the window frame height (from the head jamb down to the sill) on the left, middle and right sides and write down the smallest measurement.

3. They will measure inside the window frame from one corner diagonally to the other corner. They will measure from the other corner to corner and compare them to check that the frame is square. If the frame is slightly off, the installers can make the necessary adjustments later. If the frame is really off, the opening will require a full frame replacement.

4. They may also check the slope of the sill if there are different slope sill options on the replacement window.

Step 2: Remove The Sills

In order to remove the sills, the installer must first remove the interior stops (assuming there are stops), as well as the parting beads (typically only on the original window). They will then push in on the jambliners and pull the sash forward. They must pivot each side of the sash upward in order to remove them from the jamb liner.

Step 3: Remove The Jamb Liners

For aluminum or vinyl jambliners, the installers will remove them using a flat pry bar. For original windows, the installers will remove all remaining stops and leave both the exterior and interior casings untouched.

Step 4: Touch Up The Frame

The installers will take off any loose paint, debris and dirt from the frame jambs. They will touch up or patch holes or any cracks using a standard wood grade putty. They will quickly sand the jambs and may even prime and/or paint the surface. The level of detail (or if they do anything at all) are the sorts of steps that separates the quality installs from the rush jobs.

Step 5: Remove The Sash Weights

In the case of original windows, the installers should remove the sash weights from the side jamb pockets.

Step 6: Insulate The Jambs

The installers should remove any existing fiberglass from the jamb side weight pockets and insert a low expanding insulating foam into the frame pockets. Foam is better than traditional fiberglass at sealing the area and making it air tight. However, inserting too much foam can bow the frame and void a warranty so this must be done correctly. If the installers are removing the original windows, the installers may drill several 3/8" holes in the sill and the head jamb. They will then insert the foam into the holes and allow time for the foam to harden.

Step 7: Caulk The Opening

They will run a bead of elastomeric caulk along the sides and along the top of the exterior casing or along the blind stops. They will also caulk around the window sill.

Step 8: Insert The Window

The installers will place the bottom edge of the window onto the sill (they will be inside the room) and then tip it forward and up so that it presses tightly against the caulk on the casing or the blind stops.

Step 9: Shim And Adjust

With the window siting in the opening, the installers will check to make sure the window is square and plumb. They will measure from one corner to the other and vice versa to make sure the opening is square. They may need to insert shims underneath or on the sides to center the unit. They will test the window to make sure that it opens and closes properly as well as locks in place. Once they are sure the window is square, plumb and centered, they will use screws that come with the replacement window and drill them into the predrilled holes to secure the new window. They will then trim the shims with a utility knife so they lay flush with the frame.

Step 10: Insulate And Caulk

The installers may have to place some low expanding foam to fill any gaps that may still exist between the frame and exterior casing. They will then place a bead of caulking on the exterior to properply seal the window and then caulk the interior as well.

Step 11: Reinstall Stops And Trim Work

The installers will then reinstall the stops on the interior and/or exterior and do any necessary trim, staining or prepping. With vinyl windows, this is not necessary, although many times homeowners will ask for the exterior trim to be capped with aluminum flashing (this adds to the per opening replacement price).