Fit a Roman Blind With Hillarys Blackout Lining in 6 Steps for 90% Light Block

Measure the recess before anything is cut, and take three width readings: top, middle and sill. Windows rarely sit square. A reveal that shows 980mm at the top may narrow to 968mm at the sill, and a headrail cut to the larger figure will jam when the blind moves.

Use the smallest width, then subtract 10mm for clearance. That gives the headrail length for a recess fit. For a face-fix outside the recess, allow at least 60mm overlap on each side so the Hillarys blackout lining covers the vertical edges, which are usually the worst place for light leaks.

The lining may arrive as a separate panel bonded to the back of the decorative fabric, or as a pre-laminated fabric. The bonded version tends to sit flatter and keep the horizontal fold lines cleaner with use. With a loose lining, align the grain of both fabrics before tacking. A 5mm drift across a 1.2m drop becomes a diagonal pucker once the blind is raised and backlit.

Why the side gap decides the job

On a decent blackout Roman blind, the fabric is usually doing its work. The Hillarys coated lining stops nearly all light through the face of the blind. The problem sits around the perimeter, where an 8mm to 15mm channel of daylight can run down each side of the recess at 6am in June.

That bright strip is the complaint people remember after the fitter has gone. A recess-mounted Roman blind needs a little room to clear the reveal, otherwise it scuffs when it rises and falls. The clearance that keeps the blind moving also gives daylight a route into the room.

For a result above 90 percent light block, choose a face-fix that overlaps the wall or add a slim blackout side-channel. The channel is an L-shaped strip screwed to the reveal so the blind tucks behind it. It keeps the recessed look, although it adds about 40 minutes to the job and needs a straight screw line. If the line wanders, the blind catches.

Most rooms can manage without that channel. A north-facing study with a 1m window will sit comfortably in the high 80s for light block when the recess fit is neat. A south or east bedroom where someone sleeps past sunrise is different: the perimeter light matters there, and the face-fix earns the extra wall coverage.

Check the rail before the fabric goes near it

Clip the empty headrail into the brackets before attaching the blind. A bare rail is easy to level, easy to remove, and far less awkward than a lined Roman blind hanging from one half-secured bracket.

The six steps, in order

Step one is bracket marking. Headrail brackets should sit 50mm to 75mm in from each end of the rail. For any blind wider than 1.2m, add a centre bracket so the rail does not bow under the weight of the lined fabric. Hold the rail up, mark through the bracket holes with a pencil, then check the marks with a spirit level. Window frames often lean enough to throw the folds out.

Step two is drilling and plugging. Into plaster over brick, use a 6mm masonry bit and a brown wall plug. Into a timber reveal, drill a 3mm pilot hole and screw straight in. The bracket screws are under load every day, and a plug that spins in the hole will let the rail sag within weeks.

Step three is fixing the brackets and testing the empty rail. Clip it in, sight along the bottom edge, and put the spirit level on the rail itself. This is the point to correct a low end, because the fabric will exaggerate any slope once the blind is hanging.

Step four is attaching the blind to the rail. Most Roman blinds use Velcro along the top of the headrail, with the matching strip sewn to the blind. Press along the full length, including both corners. A weak patch on the Velcro line is enough to make one corner droop.

Step five is threading and tensioning the cords. The cords run through rings sewn to the back lining in horizontal rows, then up through the rail and across to one side. Pull each cord until the folds form evenly. If the bottom fold sits proud while the upper folds bunch, adjust the cord tension before blaming the fabric.

Step six is fitting the cord cleat or child-safety tensioner. It must sit low enough to secure the cord, with no reachable loop for a child, as required under UK blind safety standards. Wind the cord, raise the blind, lower it again, and check that each fold lifts level across the width.

A measured recess example

Take a bedroom window with a recess measuring 1,140mm wide at the top, 1,132mm in the middle, 1,128mm at the sill, and 1,560mm deep from reveal to glass, with a 1,480mm drop to the sill. The smallest width is 1,128mm. Subtract 10mm, and the headrail is cut to 1,118mm. That leaves 5mm clearance on each side, which is exactly where daylight finds its way through.

With a plain recess fit and Hillarys bonded blackout lining, those two 5mm side gaps plus a little spill at the bottom fold put the room around the 90 percent light-block mark on a bright morning. That will be enough for many bedrooms and studies. For a light sleeper, move to a face-fix: cut the rail to 1,260mm so the blind overlaps the wall by about 60mm each side, then mount the brackets 100mm above the reveal. The light then falls mainly to a thin line at the bottom.

Switching to face-fix uses the same blind and lining, a few longer screws and four extra wall plugs, so the cost barely changes, while the appearance changes more noticeably because the blind reads as a panel on the wall instead of a fabric set neatly inside the frame. In a small room, that extra wall coverage can make the window look heavier.

The tools that actually matter

For a recess fit, the useful kit is simple: a combi drill, a 6mm masonry bit, a Phillips bit, a spirit level at least 600mm long, a steel tape and a sharp pencil. The level is the item worth taking seriously. A short 200mm torpedo level can sit true on a sloping reveal and give a false reading for the rail, and a crooked rail makes the folds taper toward one side.

For a face-fix, add wall plugs sized to the screw. If the wall is plasterboard and there is no stud behind the bracket line, use spring toggles or a metal cavity fixing. A standard plug in hollow plasterboard will tear out under the daily pull of raising the blind.

Keeping the folds crisp afterwards

Lined Roman blinds keep their shape best when raised fully every few days, because the folds re-form along the sewn ring lines. Leaving one half-raised for a month encourages a memory crease in the lining.

The permanent crease usually shows first on the blackout lining, exactly where the sewn ring rows were meant to guide the fabric to fold.