Things You'll Need
Double sided tape
When installing a window shade or blind inside the window frame, a gap between the edge of the shade and the window casing will allow light to enter the room. In areas such as a bedroom or media room where complete light blocking is required, it may be necessary to mount the window treatment outside the frame instead. Another option is to add fabric drapery panels on both sides of the window to cover the light gap completely.
Measure the width of your window opening, including any casing, to determine the size of drapery rod needed. Add a minimum of 12 inches to this dimension so the rod extends 6 inches past the window on each side for optimum coverage.
Install the drapery rod four to 6 inches above the window. Choose between standard lengths of 84 and 96 inches for ready-made drapery panels based on your window height.
Choose curtains with rings, and pull one ring past the bracket supporting the rod to extend the drapery as far as possible.
Purchase a drapery rod that returns the fabric to the wall to bring the fabric close to the wall and block light seeping in through the sides of the panels. Fold the fabric 1 inch, and adhere the fabric to the wall with double-sided tape for maximum light blocking.
Drapery rods 60 inches or wider should be installed using three brackets for added support.
Consider installing window shutters instead of shades or blinds. The frame on a shutter is mounted outside your window frame eliminating light gaps.