How to Add a Window to a Bathroom

Plan for the window location on the outside wall. Try to use a wall that isn't bricked on the outside as this is a complicated demolition and installation. Using a stud sensor, determine the position of interior wall studs.

Verify on the inside of the room that the wall is free of electrical and plumbing lines. Plumbing is easier to determine by choosing a wall away from sinks. Electrical is more difficult to gauge as you have little to no way to know for certain the location of interior wiring without actually cutting into the wall.

Mark the point on the wall for the bottom of the window at a comfortable level. Measure the length of the wall for the window and locate the center point. Take the horizontal dimensions of the new window, divide it in half and mark out from the center point on both sides to determine the location on the wall

Build a frame from 2-by-4 boards to match the size of the window. Use wood glue and 3-inch screws to create a strong frame.

Cut through the wall and wall studs for a size just enough to fit the wood frame. Fit it securely in the gap and anchor it to the cut studs with wood screws at the top and bottom. Fit horizontal braces between the frame and the nearest studs to anchor it tightly in place.

Place the window into the frame. Add two screws, one in each corner, to hold it in place. Use a level to make sure the window is straight. Use wood shims to balance it properly on the frame. Add screws at the bottom to stabilize it. Adjust it to perfect level and secure the new window tightly to the frame.

Replace any interior wall material and add an interior frame or trim molding to hide the installation. Add exterior framing and finish the outside tightly against the elements. Use weatherstripping and caulking to seal it.