Windows in garden sheds and other outbuildings occasionally weather to the point that replacement is necessary. A new window improves the appearance of the shed and makes the building more weathertight and may improve its security. Replacing the shed window with one of an identical size is a project most DIY enthusiasts can accomplish in a single day with common carpentry skills and tools.
Remove the window trim, if it exists, on the interior of the shed window. Buildings that have not been finished on the interior usually don't have interior window trim.
Remove the exterior trim around the window. Use a crow bar to work the trim boards loose. Set the trim boards aside for possible reuse.
Remove the window sashes. These are the framed glass panes within the window frame. Commonly this involves removing the window jambs or frame pieces that hold the sashes in place. Handle the sashes carefully to avoid broken glass.
Pry the window frame from the wall opening. Work the trim loose of the trim nails driven through the frame into the wall studs. The nails may pull through the trim and can be removed from the stud later. Clear away any shims or wedges used around the old window.
Place the new window in the window opening. Place shims, thin pieces of wood used to fill gaps, between the window frame and stud walls to create a solid fit. Check the level of the window frame using a short spirit level. Adjust the level using shims or small wedges of wood if necessary.
Nail the window in place using 7.5 cm (3 inch) finishing nails. Alternatively, use 7.5 cm (3 inch) deck screws to attach the window frame to the stud walls.
Replace the exterior trim using the boards salvaged, if possible. Alternatively, replace the trim with new boards cut to size. Nail the trim in place with 5 cm (2 inch) finishing nails.
Choose a window sized to fit the opening. Using a replacement window of a different size involves adding or removing parts of the stud wall as well as the exterior siding and is a much more difficult project.
Handle the window sashes carefully especially if the glass has been broken, resulting in sharp edges.