Blackout vs. room-darkening shades: what you are actually buying

Fabric is only half the story

People buy a "blackout" shade, install it inside the window frame, and are surprised by bright lines of light down both sides at 6 a.m. The fabric did its job; the gap did not. An inside-mount roller shade must clear the frame by about a quarter inch each side, and that is where the light gets in.

Three ways to get an actually dark room

• Side channels: slim aluminum tracks on each side of the window that the fabric runs inside. The most effective option; adds roughly $75 to $150 per shade.
• Outside mount: hang the shade on the wall above the window, 2 to 3 inches wider than the opening each side. Cheap and effective where there is wall space.
• Layering: a blackout roller shade behind lined drapery panels. The drapery covers the gaps and softens the room.

When room-darkening is enough

Living rooms, offices and kids' playrooms usually want room-darkening or light filtering, not blackout: the room stays usable without turning on lights. Save true blackout for bedrooms, nurseries, media rooms and anyone who works nights.

Dual shades: both in one bracket

A dual roller puts a light filtering or solar shade and a blackout shade on one set of brackets. Daytime you use the sheer; at night the blackout. It is the most common bedroom setup we install on the Treasure Coast.