Loft windows, skylights and dormers are all openings in a roof that allow more light inside under the rafters. Dormers usually have vertical windows while loft windows and skylights follow the plane of the roof. Windows can be bubble types that rise above the roof line or lie flat along the roof. Some styles open to allow air in. Most use polycarbonate, plexiglass or similar materials which are less prone to damage than glass. The framing is similar – roofing is removed, rafters are cut, horizontal braces are added and a rough frame is built to hold the window in place.
6 If the interior of the loft or other space is finished, you may have to cut out drywall to make space for the window and patch it once the window is installed.
Make a rough frame for the window. Measure the top and bottom points for the frame. Place horizontal double 2-by-4 headers between the rafters at the top and bottom of the window area. Nail the boards together with 16d framing nails and a hammer then mount them in place with framing nails driven through the rafters into the header ends. Use a level to set these boards evenly.
Apply roofing paper and metal flashing around the edges of the roof or loft window. Lift the shingles around the window frame with a pry bar just enough to slide the paper and flashing under them. Fasten the flashing with shingle nails. Run flashing up the sides of the window and over the roof to seal the junction. Replace any shingles that were removed.