A window shelf can be a sunny place for growing indoor plants or herbs. You can hang window shelves on any type of window, with the brackets on the outside of the window for windows that have a narrow jamb or on windows with a recessed jamb that is wide enough for the shelf. You can hang a window shelf on any type of wall surface including drywall, wood or masonry.
Measure the width of the area where you will hang the window shelf. If you are hanging the shelf in a recessed windowsill, measure the distance between the two sides of the window. If hanging the shelf with brackets on the wall beside the window, measure the width of the window past the trim, add the width of the shelf brackets and add 2 inches to allow for an inch of overhang on each bracket.
Purchase glass shelves cut to the necessary size, and be sure the edges have been rounded to prevent cuts.
Determine the height for the window shelf, or shelves, based on the size of the objects, plants or display items you want to place on the shelf. If using the window for plants, allow room for plant growth.
Measure from the bottom of the windowsill, and use a pencil to mark the wall or the window recess on one side for the first shelf.
Hold the bracket on the mark, if using a wall-mounted bracket, and mark the location for the screw holes in the bracket. If hanging in a recessed window, hold a piece of wide trim at the mark and draw a cut line by tracing the back of the trim with the outside of the window frame. Cut two pieces of the trim to the determined width with a saw for each window shelf.
Pre-drill 1/8-inch pilot holes into the wall for outside brackets. If hanging the shelf in a masonry surface, use a masonry drill bit. Hold the trim in position, use a small level to level the trim and pre-drill through the trim and into the wall for at least two screws if hanging the window shelf in a recessed window.
Screw the bracket or trim in position on only one side of the window.
Place the shelf in position, and place a level on top of the shelf.
Hold the bracket or trim for the opposite side, and adjust up or down until the shelf is level. Mark the location for the wall bracket or wide trim with a pencil. Remove the shelf. Pre-drill pilot holes and hang the opposite side with the appropriate screws.
Place the shelf on the brackets or wide trim. Repeat for each additional window shelf.
Choose masonry screws for masonry surfaces or coarse-threaded screws for wood or drywall. If hanging brackets into hollow wallboard, insert hollow wall anchors to be sure the shelf will not pull out of the wall.