This is the sister post to our general blackout guide . Where that one covers bedrooms and nurseries in depth, this one is specifically for home theatres, media rooms, and shift-worker bedrooms — the three environments where "pretty dark" is not good enough. Why home theatres need a different spec Bedroom blackout is about sleep quality. A tiny sliver of light around the shade edge doesn't wake you up. Home-theatre blackout is about picture quality — even small amounts of ambient light wash out contrast on OLED and projected images, and reduce perceived resolution by up to 40% (measured, not marketing). The four-layer media room spec Layer 1: exterior control If the media room has any exterior wall glazing, install exterior outdoor roller blinds — they stop UV and heat before it enters the window cavity. Bonus: reduces cooling load on the AV rack by 15–25%. Layer 2: cassette + side channels Interior blackout roller shade mounted in a full cassette with rigid side channels. This eliminates the two-finger-wide light gap between the fabric and the wall that standard rollers leave. Channels are what separate "hobbyist" from "pro" home cinema. Layer 3: pelmet or valance A top-facing pelmet blocks the light bleed from where the fabric wraps the roller. This is the single most-missed detail in DIY installs — you can save 90% of light bleed for $60 of MDF and paint. Layer 4: room dark…