Question answered
Are roof windows secure?
The short answer
Roof windows are generally harder to reach than wall windows, so they are a less obvious target, but they are not immune. Look for a key-locking handle or a lockable ventilation catch, laminated glass on the inside pane, and a frame fixed securely into the rafters. Windows that can be reached from a flat roof, garage or neighbour's wall need the most attention. In a bedroom, any lock must still release quickly from inside.
Roof windows are harder to reach than ground-floor windows, but not out of reach. The lock, the glass and the way the frame is fixed decide how well one resists a determined visitor.
Where the risk really comes from
The question is not whether a roof window is high up, but whether someone can reach it. A window on the top of a steep two-storey slope is awkward to get at. A window in a rear extension roof, a lean-to, or a loft slope above a flat garage roof can be reached from a wall, a shed, a bin store or a ladder left outside.
Scaffold is another way in. While building work is under way, a scaffold gives easy access to every window it passes, and a roof window left unlocked at night during a job is an open invitation. It is sensible to ask on any job where the scaffold goes and what is locked each evening.
Look at the whole approach. If a person can climb onto a low roof, the window there should be treated like a ground-floor one, with the same standard of lock and the same checks that it closes tight.
Locks, catches and handles
The usual protection is mechanical. Many roof windows have a handle that locks with a key, and a ventilation catch that holds the sash a short way open so air gets in while the gap is too small to climb through. Check how each one is operated and that the key can be kept out of sight but within reach in an emergency.
Electric and solar-powered windows add a control that can be locked or switched off, and a rain sensor that closes the sash if wet weather arrives. Our answer on rain noise and roof windows covers another side of how a window behaves in a storm.
Older windows may have worn catches, loose hinges or a sash that no longer closes flush. A lock cannot do its job if the sash can be levered away from the frame, so we check the fit as well as the hardware.
Glass: laminated against toughened
Glass is the other half of the answer. Laminated glass has a plastic layer between its panes, so a blow cracks it but does not make a hole, and it holds together long enough to slow a break-in. Toughened glass is strong against impact, but when it fails it breaks into small pieces, which leaves an opening.
Many roof windows use laminated glass for the inner pane, which is also the safer choice if someone below could be hit by falling glass. Ask for the glazing specification of the model you are being offered, and which pane is laminated, rather than assuming.
Heavier glazing can change other things, such as the weight of the sash and the sound of rain on the glass. It also affects the thermal rating covered in roof window U-values, so check that the specification you want meets the limit.
The frame and how it is fixed
A strong lock in a weak frame is wasted. The frame should be fixed through into the rafters and trimmers with the fixings the maker specifies, and the flashing and lining should not hide gaps or loose parts. At the survey we look at the timbers around an existing window for rot and movement.
If you are weighing a roof window against a dormer, a dormer has vertical windows at roof level, with similar security needs to any other upper window; the trade-offs are set out in roof window or dormer. Different makers offer different locking systems, and our page on Velux alternatives looks at the choices.
Insurance can also be affected. Policies sometimes set conditions for locks on accessible windows, so read yours or ask the insurer before you decide.
Security against escape
A loft bedroom brings a conflict. Approved Document B asks for an escape window to have a minimum area of 0.33 m2, with a clear height and width of 450 mm each, a bottom edge no more than 1100 mm above the floor, and the ability to stay open without being held. A lock that needs a key hunted for in the dark defeats that purpose.
The answer is a window that is secure by default but opens in one movement from inside, with a key kept in a known place, or a handle that releases without one. Our answer on escape roof windows explains the dimensions.
On our visit we note what each window can be reached from, test the fit of the sash and photograph the roof. The written quote follows as one total figure. Our skylights and roof windows page sets out the full range of work.
If you already have windows fitted, a simple home check helps: close each sash fully, try to lift it from outside the frame where you can reach, and look for gaps at the corners or movement at the hinges. A window that rattles or gives is worth having looked at before the nights draw in.
Roof window locks: two more questions
Can someone get in through a roof window above a flat extension?
Yes, if the flat roof can be climbed onto and the window is not locked. Treat it like a ground-floor window: use a key-locking handle, a ventilation catch, and laminated glass.
Should I leave a roof window on its ventilation catch overnight?
The catch is designed to hold the sash open only a small way. That suits an upstairs room with no easy outside access, but if the window can be reached easily from outside, fully closing and locking it is the safer choice.
Tell us about your roof
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- A written quote with one total price
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