Bay Window Blackout Blinds: Darkening Three Panes Without Three Light Gaps

Bay window blackout blinds have to close six edges instead of two, which is why a bay that looks beautifully dressed still glows at six in the morning. Three panes means three blinds, and every blind you add brings two more vertical gaps for light to run down.

That arithmetic is the problem. The rest of this is about which of the three fitting routes closes most of it, and what each one costs you in looks or in use.

Key Takeaways

• One window became six gaps. Bay window blackout blinds mean three blinds and six vertical edges, not two.

• Angles stop joins sitting flush. Neighbouring blinds step past each other at the corner, and light runs down the step.

• Overlap only works one way. You can lap blind A over blind B or the reverse, never both, so one join is always the weak one.

• A curtain beats blinds for darkness. One piece of lined fabric across the whole bay has no internal joins at all.

• Measure each pane separately. A bay is three different windows that happen to touch.

Why a Bay Leaks More Light Than a Flat Window

A flat window has four edges and you can do something about three. Fit the blind outside the recess, wider and longer than the opening, and the sides and the bottom close up almost completely.

A bay takes that away. The reveals turn inward, so there is often no flat wall to overlap on to where the panes meet, and the blind has nowhere to go but inside each section. Inside, it has to be narrower than the opening so the fabric travels without catching, and that clearance is the gap you will be looking at in the morning.

This is why bay window blackout blinds disappoint people who bought on fabric alone. The fabric is doing its job. The geometry is not.

Bay Window Blackout Blinds: Three Blinds, Six Edges

Count them before you spend anything. Each blind has a left edge and a right edge, so three give six. Two sit at the outer ends of the bay against wall and behave like a normal window. The other four meet in pairs at the internal corners, and those cause the trouble.

The panes are not in the same plane. Where two blinds meet at an angle, one hangs a few millimetres in front of the other rather than beside it, so there is a step. Light comes in at the step, runs along the reveal and lands on the ceiling, which is where you notice it from a bed.

Add the gap above each roller and under each bottom rail and the honest count is higher than six. The vertical joins are simply the ones bay window blackout blinds can still do something about.

Option One: Overlapping Blinds Inside the Bay

The usual approach, and the one most installers quote for. Bay window blackout blinds in three pieces, each sized to its own pane and fitted in the recess of that section.

The trick is to order them slightly wider than a strict recess fit so each laps past its neighbour at the corner. You choose the direction, which means one corner closes tightly and the other closes less well, because you cannot overlap both ways at once. Most people run the overlap away from the bed. The bay window blinds range covers the shapes, and the overlap is a measuring decision rather than a product one.

Rollers suit this better than anything else, because the tube can be made to the exact width of each section and the fabric sits close to the glass. Blackout roller blinds in three matched widths is the standard answer.

Three made to measure roller blinds will beat three stock sizes every time here, since no bay is built to standard widths. Made to measure blackout blinds earn their price more clearly in a bay than on a flat window for that reason alone.

Where the joins have to be properly closed rather than overlapped, a honeycomb blackout blind running in side channels seals each edge instead. You pay for it in three sets of channels and a slower operation.

Option Two: One Blind Across the Front

Run a single blind straight across the mouth of the bay, wall to wall, and you have one blind with two edges and no internal joins. For darkness alone it beats three blinds comfortably.

What you give up is the bay itself. The window seat, the sills and the reveals all sit behind the blind once it is down, so the room reads as a flat wall in the evening. In a bedroom that is a fair trade. In a living room it rarely is.

It needs a fixing point across the front of the bay, usually the ceiling or a timber batten, and the blind becomes wide enough that tube deflection matters. Complete blackout blinds at that width are heavy, and a sagging tube ruins the one advantage bay window blackout blinds across the front give you.

Option Three: Blinds Plus a Curtain Track

The darkest of the three, and the most common in practice. Three blinds inside the bay for daytime privacy and glare, and a lined curtain on a bent track across the front for night.

A curtain has no joins, no clearance gaps and no step at the corners, and a generous one overlaps itself in the middle and returns to the wall at each end. That is more closed edge than any arrangement of blinds can offer. Searches for blackout blinds bay window answers tend to end here, once people have tried the blinds on their own.

It costs more than either other option and takes up wall space. If the bay faces east and somebody has to sleep past sunrise, it is the one that works.

Frequently asked questions

How do you measure a bay window for blinds?

Treat each pane as its own window. Measure the width of every section in three places, top, middle and bottom, and use the smallest for a recess fit. Measure the drop on both sides of each section, since bay sills are rarely level. Then note the angle at each corner, because that decides how far the blinds can lap past one another. Write the sections down left to right so nothing gets swapped on fitting day.

How do you dress a bay window with blinds and curtains?

Bay window blackout blinds inside each section, curtains across the front on a bent track. The blinds handle daytime privacy and glare without covering the reveals, so you keep the depth of the bay in daylight. The curtains close the whole mouth of the bay at night, including the corner joins the blinds cannot. Hang the track high and let the curtains stack on to the wall at each end so they clear the glass by day.

How do you fit blinds in a bay window?

Each blind is fitted to its own section, usually into the top of the reveal or the window frame, working from one end to the other so any error is pushed to the final pane rather than the middle. Check the overlap direction before drilling, since it decides which corner closes tightly. On uPVC, clip-in brackets avoid drilling into the frames altogether, which matters more in a bay because there are three frames to live with.