How To Build an Interior Window

Contemporary homes are built with open floor plans, great rooms, and high ceilings — a result of current tastes, as well as programmatic and structural changes in residential architecture. Unlike homes from the mid-century and prior, the contemporary home incorporates the previously private kitchen into the public living space and capitalizes on longer span beams to create rooms that flow together.

But for those of us with older homes, creating an open floor plan would be a major undertaking, requiring complex engineering and major demolition. Still, it is possible to achieve a contemporary feel and to make your home feel bigger and brighter in a single weekend — by building an interior window.

Materials

• 2x4s, drywall
• drywall screws, framing & finish nails
• joint compound, drywall tape
• primer, paint
• trim, counter (optional)

Tools

• hammer, power jigsaw & screwdriver
• stud finder, drywall router
• metal straight edge, tape measure, triangle, level
• utility & drywall knives, paint brushes
• sandpaper, sponge

1. Determine if your wall is load bearing
Before you do any demolition, you must first determine if your wall is load bearing. The safest way to do this is to get a consultation from a building professional; it may be expensive, but it’s well worth it to ensure that you do no major damage to the structure of your home.

Note: This How To provides instructions for creating openings in 2×4 wood-frame, non-bearing walls only. Interior windows can be built in bearing walls and walls of other construction types, but that is for another post!

Here are some rules of thumb for determining if your wall is load bearing:

• If you can, take a look at the blueprints of your home. Bearing walls may be called out on the plans.
• If you can, get into the basement and attic of your home. Any walls that are built directly on top of foundation walls, columns, or beams in the basement can be assumed to be load bearing. In keeping, any walls that are built directly underneath (and that clearly support) roof rafters, columns, or beams in the attic can be assumed to be load bearing.
• Take a look at the floor joists below your wall. Bearing walls typically run perpendicular to the floor joists.
• Take a look at your wall. If it is an exterior wall or it appears that it used to be an exterior wall (i.e. before an addition was built), then it can be assumed to be load bearing.

2. Plan and mark out the opening
Once you have found a non-bearing wall to work with, carefully plan and mark out your opening with pencil or tape on both sides of the wall. Use a level, triangle, and ruler or measuring tape to ensure that you have outlined perfect, balanced, and matched rectangles. Be careful about measuring off of sloped floors or floors that are at different heights on each side of the wall. Check and double check!

Here are some things to think about in your planning:

• What will the purpose of your opening be? Will you use it as a bar with a standard dining chair, a bar stool, or while standing? Or will the opening be used to display objects or simply to look through?
• Should the size and placement of your interior window match the size and placement of your exterior windows? What proportions will look good in your room?
• Do you have a specific width and horizontal placement in mind for your opening, or would you rather allow those factors to be determined by the location and spacing of the existing studs? (Creating an opening that is framed by existing studs will cut down significantly on your work but may not result in an ideal size and placement.) Use a stud finder to help you plan.
• Are there likely to be any wires or pipes running through your wall? If so, relocate your opening or be prepared to hire an electrician or plumber.

3. Cut and remove the existing drywall
Note: If there are likely to be any wires or pipes running through your wall, now is the time to turn the power and the water off!

With a drywall router, follow your outlines to cut and remove the existing drywall from both sides of the wall. Next, take a pencil and trace the top and bottom edges of the drywall opening onto the face of all exposed studs on both sides of the wall.

Because you’ll need to frame your final opening with 2×4’s, you’ll have to remove some extra drywall to give you room to maneuver. With your drywall router, cut and remove an additional 6″ of drywall above and below your current opening.

If your final width will be determined by the existing studs, remove any additional drywall to the left and right of the current opening so that the edge of the drywall opening is flush with the inside face of those studs. If your final width is independent of the existing studs, remove additional drywall to the left and right of the current opening up to the center line of the next-closest studs. (You’ll need access to these studs to build out your frame.)

4. Cut and remove the existing studs
From the pencil marks that you made on the exposed studs, move upwards an additional 1 ½” from the top and downwards 3″ from the bottom and mark again. This will allow you room to frame the opening with 1 2×4 at the top (the “header”) and 2 2x4s at the bottom (the “sill”) and obtain your intended opening size.

Note: In a non-bearing wall with a interior window of less that 4′ in width, this framing should be sufficient. However, if your intended opening size is greater than 4′ in width or you expect to place a great deal of weight on the sill, heftier framing will be needed.

Using a jigsaw, cut along the new pencil lines and remove the stud segments.

5. Frame the opening
Measure the width between the inside faces of the studs that align with the drywall opening. Cut 3 2x4s to this width. Raise 1 2×4 horizontally to the head of the opening, carefully leveling it and securing it with a hammer and framing nails to the left and right-most studs and then to each intersecting stud. Repeat this process with 2 2x4s laid flush at the sill of the opening.

If additional framing is needed to bring in the width of the opening, measure the height between the inside faces of the head and sill. Cut 2 2x4s to this height. Insert the 2x4s vertically between the head and sill and locate them as desired. Use a triangle to ensure that they are straight and secure them with a hammer and framing nails to the head and sill.

6. Replace the drywall
Measure the areas of drywall that need to be replaced. If the inside faces of your final opening will be lined with drywall, measure this area, too.

Note: If you intend to install a counter, do not line the sill with drywall. If you intend to line the inside faces of the opening with trim, do not line them with drywall.

Mark out the necessary pieces on a sheet of drywall and score using a utility knife and metal straight edge. Cut or snap the pieces. Then, secure the drywall to the exposed studs with screws at regular intervals.

7. Finish and paint the drywall
Using joint compound and drywall tape & knives, cover the seams and screw heads until flush. Let dry before sanding and sponging to a smooth finish. Prime and paint.

8. Add trim and counter (optional)
Your interior window can now be outfitted with trim and/or a counter, as desired.

Note: If a counter is installed, be sure to provide extra support for it with brackets mounted underneath.

(Images: Sam Swift)