Window restrictors UK: the rules, the types and how to fit one

The first time they pull themselves up onto the windowsill, you'll be across the room before you've thought about it. From then on you look at that window differently, especially the one above the radiator, because a radiator is a step.

Window restrictors are the piece of baby proofing most people leave until last. Not because anyone thinks windows are safe. It's that the rules feel murky, the types are confusing, and nobody wants to drill into a uPVC frame they don't own.

So here's the whole thing in one go: what the guidance actually says, the five types, and how to fit the stick-on kind.

Key facts

• Less than 6.5cm (2.5 inches) is the NHS figure for a home with a crawling baby or a toddler; the HSE's 100mm is for health and social care premises.
• RoSPA puts child deaths from falls at around 10 a year, some from windows and balconies. Its advice is to fit child-resistant restrictors and keep anything climbable away from the window.
• Ours comes singly, in twos or in fours. No drilling, 3M adhesive, 24 hours to cure.
• Any window above the ground floor that a child can reach is the one to do first.

Are window restrictors a legal requirement in the UK?

For your own home, no. There's no law that says you, as a parent in your own house or flat, must fit restrictors. It's guidance, and the guidance is plain.

RoSPA's advice on accidents to children is to fit child-resistant window restrictors, and to make sure you can still get out easily in an emergency. Around 10 children a year die from falls, RoSPA says, some of them from windows and balconies.

In some settings it's expected rather than optional. The HSE's guidance on falls from windows in health and social care premises says openings should be restricted to 100mm or less, and that restrictors should only be releasable with a special tool or key.

That's care homes and hospitals rather than your spare room. For a home, the NHS baby and toddler safety page asks for locks or catches that restrict the opening to less than 6.5cm (2.5 inches), which is the figure to set ours to once your baby is crawling.

Two situations sit in between. If you rent, a stick-on restrictor means you're not drilling the landlord's frames, and if a window genuinely worries you, tell the landlord in writing as well as fitting one yourself.

If you look after other people's children at home, ask whoever inspects you what they want to see; the 6.5cm figure is the one to work to at home, and whoever inspects you may ask for the HSE's 100mm.

How far should a window open with a child restrictor?

Less than 6.5cm, which is the NHS figure for homes: about the width of three fingers, and small enough that a toddler can't get their head and shoulders through, which is the bit that matters.

The 100mm you'll see on packaging is the HSE's figure for care settings. Set the gap to the smallest opening that still gives you the air you want. One reviewer keeps theirs at about 5cm and still gets the room aired.

Two things undo a restrictor. The first is a climbing frame under the window: a bed pushed against the wall, a chest of drawers, a toy box, the radiator. RoSPA's line is not to put anything under the window that can be climbed on. If the cot or the bed has to go there, the restrictor is doing all the work, so check it more often.

The second is fitting it and forgetting it. Windows are an escape route. Whoever might need to open that window in a fire needs to know how the release works, and that includes the babysitter and the grandparents.

Types of window restrictor, and which fits which window

Five common types. They all do the same job, stopping the window past a set gap. They differ in how they fix on, whether you need a key, and whether they'll go on your frame at all.

If you've got uPVC, which is most UK homes now, you've got the widest choice: hinge-side, sash jammer, cable or stick-on all work. Wooden casements take cable or stick-on. Sliding sash windows are cable territory, or a sash stop screwed into the frame. Old metal-framed windows are worth a call to a window company, because a screw fixing is the safer bet there.

Do no-drill window restrictors actually hold?

This is the search that brings most people to us, and the honest answer is yes on the right frame, prepared properly, and no if you skip the prep. The adhesive is high-strength 3M, the same family of pad as our cupboard locks.

It bonds to a flat, clean, dry surface, and it comes off without lasting damage, which is why the reviews are full of grandparents, renters and, honestly, cat owners.

What it doesn't like: a uPVC frame that's had years of spray cleaner on it (there's a film you can't see), a textured or deeply bevelled frame where the pad only touches at the edges, and being tested before the 24 hours are up.

One reviewer had a frame with a raised rim that stopped the arm locking cleanly, which is the "flat surface on both parts" rule in real life. Two others found the track a tight fit on very slim modern uPVC. Measure where you want it, with the window shut, and check both spots are flat and reachable.

It's the thing we sell most of, and that's not because it's clever. It's because it's inexpensive, one reviewer timed the fitting at about ten minutes, and it does the one job.

How to fit a window restrictor without drilling

1. Pick the window and check the two surfaces. You need a flat patch on the fixed frame and a flat patch on the opening section, both reachable with the window shut. Deep bevels, heavy texture or an odd opening mechanism: check before you order.
2. Clean both patches with something that leaves no residue and let them dry completely. Not polish, not a scented spray. uPVC and painted wood carry a film of old cleaner, and that film is what fails, not the pad.
3. Decide the gap. Under 6.5cm once they're crawling. Set it for the air you actually want, not the maximum.
4. Peel and press the frame block, then the track on the opening section, following the leaflet for the positions. Press hard and hold.
5. Leave it 24 hours before you open the window against it. This is the step everyone skips.
6. Test the release yourself, then show every adult in the house. Then move the toy box away from the window.

The fitting video shows the whole thing in real time.

Questions we get asked

Do I need window restrictors on the ground floor?

The fall risk is upstairs, so do those first. Downstairs it's about a toddler climbing out and wandering, which is a real thing with a low sill and a garden. There's not much reason not to.

Can a window restrictor be opened in an emergency?

Ours can be released by an adult, and it needs to be, because windows are an escape route. RoSPA says the same: fit restrictors, and make sure you can get out. Show everyone who might need to open that window how the release works, babysitters included.

Will a stick-on window restrictor work on uPVC?

Yes, that's mostly what it's fitted to. The two things that stop it are a frame that hasn't been cleaned of old spray cleaner, and a very slim modern profile where the track is a tight fit. Measure the flat area first.

Do window restrictors work for cats?

Judging by the reviews, we sell a lot of them to cat owners, and they work for the same reason they work for toddlers: the gap is small. A determined cat gets through a smaller space than a child, so set the gap tighter than you would for a baby. It's made and sold as a child safety product, and that's the standard it's built to.

Can I fit a window restrictor in a rented flat?

Yes. The stick-on type needs no drilling and comes off without lasting damage, which is the point of it for renters. Clean the frame properly, give it 24 hours, and let the landlord know if a window is a worry.

How many window restrictors do I need?

One for every opening window a child can reach, starting with the bedrooms and the landing. Count the windows, not the rooms. We sell them singly, in twos and in fours.

Next: the window restrictor lives in the baby proofing collection with the gate, the locks and the rest. If you're doing the whole house this month, Baby Proofing 101 goes room by room, and the cupboards are covered in magnetic cupboard locks, how they work and how to fit them.