How to Fit Blackout Blinds Inside Frame

A blackout blind that sits badly inside the recess will show light gaps, catch on handles and look off even when the fabric is right. If you want to fit blackout blinds inside frame properly, the job starts before the drill comes out. Accurate measuring, the right clearance and a realistic look at your window shape make all the difference.

Inside-frame fitting is popular because it gives a clean, built-in look. It keeps the blind tucked neatly within the window recess, which suits bedrooms, nurseries and any room where you want a tidy finish. It can also save space compared with a blind fitted outside the recess. That said, it is not always the best option for every window, especially if the recess is shallow or the frame is not square.

Why fit blackout blinds inside frame?

The main reason is appearance. A blind fitted inside the frame usually looks sharper and more tailored than one fixed over the wall. It sits within the lines of the window rather than dominating them, which works well in modern homes, rental properties and straightforward room updates where you want a practical finish without fuss.

There is also a functional side. If you have curtains already, an inside-recess blackout blind can work alongside them without adding too much bulk. In smaller bedrooms, box rooms and loft spaces, that can matter. The trade-off is that blackout performance depends more on fit. If the recess is uneven or there are natural gaps at the sides, a recess blind may still let in a line of light.

Before you fit blackout blinds inside frame

Check the recess depth first. A blackout roller blind needs enough room for the brackets, the roll of fabric and any bottom bar movement. If the recess is too shallow, the blind may project forward awkwardly or rub against the window. Deep recesses are easier, but even then you need to watch for handles, vents and inward-opening windows.

Next, check whether the recess is square. In older homes this is where problems usually start. Measure the width in three places - top, middle and bottom - then the drop on the left, centre and right. If the numbers vary, use the smallest width measurement so the blind can sit inside the frame without jamming. For drop, use the full recess height unless your product instructions say otherwise.

If your blackout blind is made to measure, the deductions are often handled for you depending on how the supplier asks for sizes. Always read the measuring guidance properly before ordering. Guessing or rounding up is where people come unstuck.

Measuring for an inside-frame blackout blind

Getting the measurement right is half the fitting job. Use a metal tape measure, not a cloth one. Cloth tapes flex and that small difference can become a visible gap once the blind is up.

Measure the recess width at the top, middle and bottom. Write down the smallest measurement in millimetres. Then measure the recess drop in three places and note the longest drop if you want full coverage to the sill, or the exact finished drop if the blind is stopping above it. Keep the figures exact. Do not convert rough fractions or knock numbers up or down for convenience.

It also helps to check for obstructions. Window handles are the main one. If they stick out too far, the blind may need extension brackets or an outside-recess fit instead. The same applies if trickle vents are fitted at the top of the frame. A neat inside fit only works if the blind can move freely.

Tools you will usually need

Most inside-frame fittings are simple enough for a competent DIY job. You will usually need a drill, suitable wall plugs if fixing into masonry, a screwdriver, a pencil, a spirit level and a tape measure. A bradawl can help mark pilot points on timber, and a step ladder is worth using rather than stretching.

The fixing surface matters. Some recesses are timber lined, others are plaster over masonry, and some modern homes have uPVC surrounds. Use fixings that match the surface. The blind is only as secure as the bracket fixings.

How to fit blackout blinds inside frame

Start by offering up the brackets inside the top of the recess. In most cases, top fixing gives the cleanest result for a roller blackout blind, though face fixing within the recess can also work if depth is limited. Mark where the brackets will sit, making sure they are level and set evenly from each side.

Before drilling, check the blind position against the fabric roll and control side. You need enough room for the mechanism and a smooth drop without the fabric catching the frame. If there is a handle on one side, a slight bracket adjustment can sometimes avoid contact.

Drill the holes carefully and insert wall plugs if needed. Screw the brackets firmly into place, but do not overtighten to the point of damaging plaster or twisting the bracket. Once both brackets are fixed, clip or slot the blind into place following the product instructions.

Then test the movement. Pull the blind down fully and raise it again. It should run smoothly and hang straight. If it tilts, check the bracket alignment first. If it catches, look for recess obstructions or a blind that is too tight for the available width.

Common problems when you fit blackout blinds inside frame

Light bleed is the complaint most people notice first. Blackout fabric blocks light through the material, but it cannot stop all light around the edges if the blind sits inside the recess. This is normal to a point. If you want the darkest possible room, especially for children’s bedrooms or shift workers, you may prefer an outside-recess fit or pair the blind with curtains.

Another issue is windows that are not square. A blind can be measured correctly and still show uneven gaps because the recess itself is uneven. That is not a manufacturing fault - it is the reality of older plasterwork and frames. Measuring the smallest width avoids a blind that will not fit, but it may leave a little more space on one side.

There is also the question of fabric width versus overall blind width. On roller blinds, the fabric is narrower than the full bracket-to-bracket measurement because of the mechanism. That matters if you are expecting wall-to-wall blackout coverage inside the recess. A made-to-measure blind will still look right, but understanding this detail helps set realistic expectations.

Is inside-frame fitting always the best choice?

Not always. If blackout performance is your main priority, recess fitting can look excellent but may not give the darkest finish possible. Side gaps are usually smaller with a good custom fit, but they are not eliminated entirely. For some people, especially in a main bedroom, a blind outside the recess gives better coverage.

Inside fitting is usually best when you want a neat appearance, you have enough recess depth and the window is fairly true. It also works well if you want to keep the sill clear and avoid a blind covering decorative architrave. For landlords and quick room refreshes, it is often the most practical option because it looks smart without major changes.

Choosing the right blackout blind for the recess

Material and finish matter as much as size. A blackout blind for a bedroom should block light properly, but it should also be durable and easy to maintain. If the room is prone to condensation, a wipe-clean material may be the better choice. In family homes, simple finishes tend to work best because they are easier to live with and easier to replace like for like later on.

Colour is worth thinking about too. A recess-fit blind becomes part of the window line, so neutrals often give the cleanest look. That said, children’s rooms, guest rooms and home offices can handle stronger colours or patterns if the rest of the room is simple. The benefit of made-to-measure is that you are not stuck choosing between fit and style.

For buyers who want a straightforward route, Queen Blinds offers made-to-measure options that take a lot of the guesswork out of sizing. That is especially useful when you are trying to get the best possible inside-frame fit without paying for a full in-home measuring service.

Final checks after fitting

Once the blind is installed, look at it in daylight and again at night with interior lights on. That will show up any visible gaps, uneven drops or rubbing points. Small adjustments to bracket position can sometimes improve the finish, but if the issue is the recess itself, the answer may simply be that the window opening is imperfect.

A properly fitted blackout blind inside the frame should look neat, operate smoothly and give solid light control for everyday use. If you measure carefully and accept where recess fitting has its limits, you will get a result that looks made for the window because it is.