How to Install Blackout Shades
This guide covers the complete installation of blackout roller shades or cellular shades — choosing between inside and outside mount for your window type, measuring correctly for each mount method, positioning and drilling the mounting brackets, snapping the shade headrail into the brackets, and addressing the light-gap problem that prevents most "blackout" installations from blocking light as advertised. Blackout shades are one of the simplest window treatments to install and require only a drill, a level, and a tape measure.
The single most important insight about blackout shades: the fabric itself may block 100% of light, but light still enters around the edges of inside-mount shades and below the bottom rail. For true blackout results — the kind that allows sleep during daylight hours or prevents an east-facing window from waking a child at 5am — the shade must be mounted outside the window frame and extend past the frame on all four sides, or inside-mount shades must be paired with side channel tracks that eliminate the side gaps. The blocking quality of the shade fabric is irrelevant if the installation leaves a visible light border around the perimeter.
Time: 30–60 minutes per window. Cost: $30–$250 per window depending on the shade and mount type. Difficulty: Basic. Permit: Not required. Contractor recommended: Never for standard window shade installation.
What You Will Need
- Blackout roller shade or cellular shade with mounting hardware
- Drill/driver with 3/16-inch and 1/4-inch bits
- Tape measure
- Pencil
- Level (4-inch torpedo level sufficient)
- Stud finder (for outside-mount installations into wall studs)
- Wall anchors (if mounting into drywall without a stud — use toggle anchors, not plastic expansion anchors, for shade brackets)
Inside Mount vs. Outside Mount — the Critical Choice
Inside mount positions the shade inside the window frame opening, with the headrail and fabric sitting within the depth of the window jamb. This is the cleaner aesthetic choice — the shade integrates with the window without covering the window casing. However, inside mount creates light gaps on all four sides of the shade because the fabric width is narrower than the window opening (necessary to allow the shade to move freely) and because the headrail mechanism leaves space at the top. For strict light control, inside mount alone is insufficient without side channels.
Outside mount positions the shade above and wider than the window frame, with the brackets mounting to the wall or to the face of the window casing. When sized correctly, an outside-mount shade overlaps the window frame by at least 3 inches on each side and 3 inches above the top of the frame, and extends to the windowsill or floor. This completely covers any potential light gap and is the correct choice for bedrooms where sleep quality depends on true light blocking. The trade-off is that the shade occupies more visual space on the wall and the brackets are visible at the top.
Step-by-Step Installation
Step 01 · Measure correctly for your mount type
For inside mount: measure the exact width of the window opening at the top, middle, and bottom of the opening — windows are rarely perfectly square. Record the narrowest measurement. Measure the height from the top of the opening to the windowsill. Most inside-mount shades are ordered to exact width and the manufacturer deducts a small amount (typically 1/4 inch per side) during fabrication for clearance. Order the shade to the exact narrowest width measurement and specify inside mount when ordering.
For outside mount: decide how far the shade will extend beyond the window frame on each side (minimum 3 inches per side for blackout, 1.5 inches for decorative use). Add double that amount to the window opening width to get the shade width. For height, measure from the desired top of the shade (typically 3–4 inches above the top of the window opening, to cover the frame completely) to the desired bottom of the shade (typically the windowsill or 1 inch past it, or to the floor for floor-length installations). Order the shade to these outside-mount dimensions.
Step 02 · Mark the bracket positions
For inside mount: position the brackets at the far ends of the window jamb, flush with or set back slightly from the face of the jamb. Most headrail brackets are designed to mount within the depth of the window frame, typically 1.5–2 inches from the edge. Mark the bracket screw hole locations with a pencil — most brackets have 2 screws each. Confirm both brackets are at the same height using a level held across both marks.
For outside mount: measure from the window centerline outward to position the brackets symmetrically. Mark the bracket positions at the desired height above the window opening — typically the same height as adjacent windows in the room for visual consistency. Identify whether you are drilling into the wood window casing (preferred — no anchors needed), into the wall drywall with a stud behind it, or into drywall without a stud. Use a stud finder and mark any studs in the bracket area before drilling.
Step 03 · Drill pilot holes and mount the brackets
Drill 3/16-inch pilot holes at each marked bracket position. For wood window casing or wall studs, drive the provided screws directly. For drywall without a stud, use toggle wall anchors rated for the shade's weight — typically 10–15 lbs for a standard residential window shade. Toggle anchors provide dramatically more holding power than plastic expansion anchors in drywall and do not fail under the repeated loading of a shade that is raised and lowered daily. Follow the toggle anchor instructions for the correct pilot hole size and insertion technique.
Mount one bracket completely, then hold the headrail against it and use a level to mark the position of the second bracket. This method is more reliable than measuring both brackets from a single reference point on window frames that are not perfectly level. Screw all brackets snug but verify the headrail snaps into both brackets before fully tightening — brackets that are very slightly out of alignment with each other will prevent the headrail from engaging properly.
Step 04 · Snap the shade into the brackets
Hold the shade headrail up to the brackets. Engage one end first, then press the other end in until you hear or feel the locking mechanism click. Most roller shade and cellular shade brackets use a snap-in or tension design — the shade should engage firmly and not rattle when seated correctly. Lower the shade to full extension and raise it again to confirm smooth operation. If the shade does not run smoothly, remove it and check that both brackets are fully closed around the headrail and that the headrail is parallel to the ceiling — a canted headrail causes the shade to roll crookedly and bind.
Step 05 · Test the operation
For spring roller shades: lower the shade to full extension, pull down slightly and release — the shade should raise smoothly. If it raises too fast, lower to half way and give a sharp downward tug to increase spring tension. If it doesn't raise at all, lower fully and give another downward tug. For cordless cellular shades: raise and lower the shade by the bottom rail, testing that the lift system provides smooth, even resistance through the full range. For motorized shades: pair with the app or remote per the manufacturer's instructions and test up/down limits.
Step 06 · Address light gaps (critical for true blackout)
After installation, observe the window in daylight from the dark side of the shade. Note where light enters around the edges. For inside-mount installations, the side gaps between the shade fabric and the window jamb admit light that defeats the blackout rating. Three solutions: (a) add clip-on or adhesive side channels (available from most shade manufacturers as accessories) that create a light seal between the shade edge and the jamb, (b) add a second layer of conventional window treatment (curtains hung on a curtain rod mounted outside the window frame) over the roller shade to block edge gaps, or (c) replace inside-mount shades with outside-mount shades sized to overlap the frame by 3 inches per side. Option (c) is the only true permanent fix for critical blackout requirements.
Step 07 · Child safety check
Corded window coverings require that cords are secured out of reach of children under age 6. If the shade has an exposed operating cord, install the provided cord cleat or tensioner to keep the cord taut against the wall or window frame at a height above 60 inches from the floor. Verify that no looped cord hangs freely within a child's reach anywhere in its operating range. Cordless shades are the safest choice for bedrooms where young children sleep, and most blackout shades are available in cordless versions at comparable prices.
Common Mistakes and What to Watch For
- Inside-mount shades on windows with insufficient depth. Inside-mount brackets require a minimum window jamb depth — typically 3/4 inch to 1-1/2 inches. Shallow window jambs cannot accommodate inside-mount brackets. Measure the jamb depth before ordering inside-mount shades.
- Ordering exact window width for outside mount. Outside mount shades ordered at the exact window width have zero overlap on the sides and no light blocking advantage over inside mount. Add at least 6 inches total width (3 inches per side) for outside mount.
- Unleveled brackets. Brackets that are not level relative to each other cause the shade to roll crookedly, creating a diagonal gap at the bottom when extended. Level the bracket positions before drilling.
- Plastic expansion anchors in drywall. Plastic expansion anchors fail under the repeated load cycling of a window shade and pull out of the drywall within months. Use toggle anchors for any bracket that is not landing in a stud or wood casing.
- Assuming "blackout" fabric = blackout installation. The fabric spec is irrelevant if light enters around the edges. True blackout requires proper sizing and mounting to eliminate perimeter gaps.
- No child safety assessment. Corded shades in children's rooms are a strangulation hazard. Always confirm cord management on installation and switch to cordless models in any room where young children sleep.
When to Call a Pro
Professional installation is generally not required for standard window shades. Consider it for motorized whole-house systems with smart home integration, for windows taller than 10 feet requiring a ladder, or for very large exterior-mount installations over stone or masonry facades requiring masonry anchors.
Maintenance After Installation
Dust roller shade fabric monthly with a lint roller or a clean, barely-damp sponge. Cellular shade fabric can be vacuumed on the lowest setting with a brush attachment. Do not dry-clean blackout roller shades — the blackout coating on the fabric back can separate from the face fabric with chemical cleaning. If the spring mechanism on a roller shade weakens over time (shade won't retract), most roller shade tubes can be removed from the brackets and re-tensioned by rolling the tube 3–4 full rotations in the raise direction before reseating.
Blackout Shade Materials — Fabric Ratings Explained
Blackout shade fabrics are rated on a light-blocking scale from light filtering through room darkening to blackout. True blackout (sometimes marketed as "total blackout" or "100% blackout") uses a fabric with a three-pass coating on the back: two layers of opaque coating sandwiching a light-reflective layer. When a fabric sample is held up to direct sunlight, zero light should be visible through a genuine blackout fabric. Room-darkening fabrics block 85–99% of light — enough for comfortable daytime sleeping in most situations but insufficient for shift workers, infants, or extreme light-sensitive sleepers.
The fabric's blackout rating is tested at the center of the shade, not at the edges. This is the technical reason that even a "100% blackout" fabric still allows light infiltration around the perimeter of an improperly mounted shade — the test measures the material, not the installation. A shade with true blackout fabric, properly sized and mounted with adequate overlap, can reduce a fully-lit bedroom to near-complete darkness. An inside-mount shade with blackout fabric and no side channels admits light around all four sides, producing a bright border that wakes most sleepers regardless of the fabric's center-panel rating.
Motorized and Smart Blackout Shades
Motorized blackout shades use a battery-powered or hardwired motor in the headrail to raise and lower the shade via a remote, wall switch, app, or smart home voice control. Battery-powered motors are the easiest retrofit — no wiring required, installation is identical to manual shades. Battery life is typically 1–2 years per charge for average use. Hardwired motors require routing low-voltage wiring behind the wall to each shade, which is a significant installation step but enables permanent power with no battery maintenance. For a whole-bedroom or whole-home smart shade system, hardwired motors are the professional standard.
Smart shade integration (Alexa, Google Home, Apple HomeKit, IFTTT) allows schedules that automate blackout control — shades close automatically at sunset and open at a timed morning wake-up. For households with children, automatic shade schedules are particularly useful: a 7am automatic open eliminates the need to enter the room to control the shades and allows a gentle light-based wake rather than an abrupt alarm. Most smart shade motors are compatible with multiple smart home ecosystems — confirm the specific motor's compatibility before purchasing if you have an existing smart home ecosystem.
Window-Specific Considerations
Bay windows require three separate shade units (one per panel) or a custom-made unit that spans multiple panels. For inside mount in a bay window, measure each panel's width independently — the panels are rarely the same width. Outside-mount shades on a bay window require careful planning: each shade's side overlap must account for the angle between panels, or the overlapping shades will contact each other. Typically, each panel gets its own outside-mount shade sized for that panel with standard overlap, and the corner posts of the bay provide a natural light-block between shades.
Skylights and roof windows require specially designed skylight blinds or shades that mount directly to the window frame with clips rather than bracket hardware on a wall or ceiling. Standard roller shade brackets cannot be installed at the angles required for a skylight. Most skylight manufacturers (Velux, Fakro, etc.) sell purpose-made blackout blinds for each window model — confirm the make and model of the skylight before ordering a blackout covering for it.
Blackout Shades in Nurseries and Children's Rooms
Pediatric sleep research consistently shows that darkness is one of the most effective environmental factors for achieving longer, more consolidated sleep in infants and toddlers. Melatonin production, which regulates the sleep-wake cycle, is suppressed by light exposure and begins as ambient light drops below approximately 10 lux. A properly installed blackout shade in a nursery can reduce ambient light to near zero, supporting an earlier and more reliable bedtime. The practical result is often 30–60 minutes of additional nighttime sleep and easier nap transitions — making this among the highest-ROI bedroom improvements per dollar in a young family's home.
For nurseries and children's rooms, cordless shades are the only acceptable choice. CPSC data documents dozens of child strangulation fatalities from window blind and shade cords annually; corded shades in rooms where children sleep or play are a documented safety hazard. All major shade manufacturers offer cordless versions of their blackout lines at comparable prices. For outside-mount installation in a child's room, use toggle anchors rated for at least 3 times the shade's weight — the shade will be raised and lowered multiple times daily for years, and properly rated hardware eliminates any concern about bracket failure.
Layering Window Treatments — Sheer Plus Blackout
In bedrooms where the window is prominent and aesthetic quality matters beyond pure light-blocking function, a layered window treatment combines a sheer roller shade or linen sheer curtain with the blackout layer. During daytime use, the sheer layer diffuses natural light softly without full blackout, maintaining the visual openness of the room. At night or during sleep hours, the blackout layer (behind or in front of the sheer) is engaged for full light blocking. This approach is particularly effective on large or architecturally significant windows where a single blackout panel would dominate the room's visual character.
The practical setup: mount a double curtain rod system — the inner rod near the wall carries the blackout roller shade bracket or a back-mounted blackout curtain panel; the outer rod (3–4 inches from the wall) carries the sheer curtain. The blackout panel and sheer panel can be operated independently. This layering system is common in hotel rooms and interior design projects and is consistently well-regarded by sleep researchers as it satisfies both daytime ambiance and nighttime darkness without compromise. The total material cost for a layered system on a standard bedroom window is $80–$200 depending on shade and curtain selection.
Custom-Size Shades for Non-Standard Windows
Many bedrooms in homes built before 1990 have non-standard window sizes that fall outside the stock dimensions available at home centers. For outside-mount installations, this is rarely a problem — any shade can be cut down from a wider size to match a custom outside-mount width, and height is limited only by the shade's maximum length. For inside-mount shades in odd-width windows, custom-made shades (ordered to exact dimensions from online retailers like Smith+Noble, SelectBlinds, The Shade Store, and many others) are the correct solution. Custom shades typically ship within 5–10 business days and are priced only slightly above stock shades for standard fabric choices. Order with the manufacturer's exact deductions applied — specify "inside mount" at checkout and confirm the retailer deducts the appropriate clearance from the ordered width. A custom inside-mount shade ordered at the exact rough opening width will be too tight to raise and lower without binding.
Related guides: How to mount a headboard. See the full bedroom install index for all bedroom projects. For window treatment options in other rooms, see the Install lane overview.