Window Installation

Some types of window installation will definitely require the services of an experienced window installer. However, a DIY homeowner with advanced carpentry skills who is familiar with framing can usually handle a window installment project on their own. Especially when working with standard-style windows 3 ½-feet wide or smaller.

Wall construction/anatomy knowledge is important when installing windows. Before beginning a window installation project, you might want to refer back to Chapter 1, House Structure Basics, under sections “Walls – Interior and Exterior” and “Walls – Load and Non-load Bearing,” found on page 30.

Guidelines for Window Installation Project Success

• Following the clearance recommendations of the window manufacturer, size the placement window slightly smaller than the opening. Carefully measure for the window’s opening; width, height, and depth. Note: vinyl frames require more clearance than those made from other materials.
• Carefully plan the window’s location to avoid plumbing, heating, electrical lines. Note: while wiring can easily be relocated to accommodate new window placement, pipes and ductwork are another matter entirely.
• Check local building codes before replacing old windows with new. There may be certain guidelines that must be met; such as window type, size, grade of window and glass type used. In addition, wind load guidelines for coastal and mountainous areas may also apply.
• When ordering windows from the manufacturer, allow extra time for custom-sized windows, and windows using tempered glass. High-performance windows with special coatings usually require an even longer lead time.
• Carefully consider new window rough-in dimensions; the exterior opening needs to be only slightly larger.
• Make sure new window installation is level, square, and plumb. Otherwise, the sash will not close properly and weather stripping may not provide a proper seal.
• Work from the inside out. Mark window location, and then remove the wall surface from ceiling to floor; to the inner edge of the first stud on either side of the rough-in measurement.
• Wait until just before inserting the window to cut the exterior sheathing and siding.
• Pre-drilling fins and frames is recommended; countersink anchors installed through wood jambs.
• When installing windows with wood frames, use a good-quality primer and exterior paint or sealer. Untreated wood or wood not properly protected that is exposed to outside elements will warp and deteriorate.
• Follow manufacturer’s recommendations on acceptable protective coatings and application techniques to avoid damage to new, unpainted wood framed windows.
• When wood is cedar or redwood and paint is used instead of a sealer, a special primer is required to prevent wood oils from bleeding through the finish.
• When painting frames, remove sashes first; put back together once paint has completely dried. Never apply paint to weather stripping or other non-wood parts.
• Allow about 8 to 10 hours to complete a window installation project.

Also, when replacing old, standard-glass windows consider safety or tempered glass as replacements. In fact, this may be a building code requirement. Such code requirements normally exist for windows subject to “human impact.”

Human Impact Windows

Human impact windows are those attached to entrance doors, and windows adjacent to a door. Also included are windows placed within a certain distance arc from a closed door; usually 24-inches.

Windows larger than 9-feet are considered human impact windows when the bottom is less than 18-inches above the floor and the top more than 36-inches above the floor. And windows placed within a horizontal walking path of 36-inches to the window.

Actual Installation

Tools required for window installation:

• Hammer
• Corrosion-resistant nails / screws
• Chisel
• Keyhole saw or reciprocating saw
• Circular saw
• Carpenter’s square
• Level
• Nail set
• Caulking gun
• Standard drywall or plaster tools

Materials required:

• 2X4 trimmers
• Enough 2X4 to construct a sill with cripple studs as outlined in step 6 of “How to Install a Window” (see below)
• Enough 2X6 and ½-inch plywood to construct a header for the window opening as outlined in step 5 of “How to Install a Window” (see below)
• Shims
• Materials required to refinish the interior wall once window installation is completed
• Caulk

How to Install a Window

If applicable, remove the old window, and then follow these 12 easy steps for new window installation:

1. Once you have carefully planned new window placement, mark the opening.
2. Using a chisel and then a keyhole or reciprocating saw, cut the opening for the window from the ceiling to the floor along bordering studs. Be sure and leave the sole plate intact.
3. Remove any studs that will be interrupted by the window. Cut through the center; carefully pry them away from the sheathing. Also remove any other obstructions, if any; including loose materials and old caulk.
4. Nail 2X4 trimmers to the studs located at either side of the opening; the trimmers will support the window’s headers.
5. Build a header; use two 2X6 boards with a scrap of ½-inch plywood sandwiched in between. Install the header on top of the trimmers.
6. Build a 2X4 sill supported by cripple studs. And then nail 2X4s between the header and sill, framing the side jambs at the rough-in dimension width.
7. Cut out the exterior sheathing and siding. If working from the outside, drill pilot holes to mark corners first.
8. Set the window in place from the outside; make sure it is level and plumb. Trace around the molding; cut away siding to the trace line.
9. Level the window again. Insert shims, and nail the window to the framing through the exterior casing into the studs.
10. Inside, insert shims and nail the sides of the window frame (the jambs) to the studs.
11. Insulate between the frame and studs; foam backer rod or loosely packed insulation is the preferred. Non-expanding, one-part polyurethane foam is acceptable if carefully installed and not used in excess – which could cause frame distortion. NEVER USE EXPANDING FOAM. Note: do not over pack insulation between the window frame and studs. This could put too much pressure on the window frame and distort it; impeding smooth operation of the sash.
12. Refinish the interior wall, and then attach the inside window casing. Caulk around the window frame on the exterior.

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