Can a Roof Window Be a Fire Escape?

An escape window is a way out of a room if the stairs are blocked by smoke or fire. Approved Document B, the part of the Building Regulations that deals with fire safety, sets the tests. The window must be big enough to climb through, low enough to reach and positioned so that someone can get from it to the ground safely.

The ground part is what rules out most roof windows. An escape window only serves a storey within 4.5m of the ground, because beyond that height a person climbing out cannot be reached by a ladder or expected to drop safely. A room on the second floor of a Victorian terrace sits far above that line, however large the roof window is.

Other points the officer will check are the clear opening size, the height of the sill above the floor and whether the sash holds open on its own. These come from the guidance, so we do not quote figures here; your plans are checked against the current edition of the document.

It helps to picture the sequence. Someone wakes in a loft bedroom while smoke fills the stairwell below. The protected stair, with fire-resisting walls and doors around it, is meant to stay usable long enough to leave by the front door. That is the escape plan the regulations favour for a house with three storeys.

A single-storey home with rooms in the roof is the case where a roof window can work as the way out, since the sill sits near enough to the ground. On a two-storey house the loft becomes a third storey, and the regulations ask for the stair to be protected: enclosed in fire-resisting construction down to a final exit, with the doors fitted to suit. A skylight cannot stand in for that.

The bungalow case works because the room is close to the ground. A chalet bungalow has its upper rooms tucked into the roof, so a roof window set at a sensible sill height lets a person climb out and reach the garden. Ask your designer to mark the window on the drawings as an escape window so the officer can check it.

Even when a roof window is not the official escape route, an opening unit still earns its keep. It can help clear smoke and stale air, and an opening roof window can count towards purge ventilation for a room under Part F. A venting sash also gives firefighters and anyone in the room another way to open up a space.

Part K does not require laminated glass in a house roof, but laminated inner panes are a sensible recommendation over a bed or stair, since they hold together if hit. That is a choice for comfort, not a rule.

On Victorian and Edwardian terraces in Bristol and Bath, the existing stair often runs up through the middle of the house. Turning that into a protected stair is a design task for the loft conversion, handled before any roof window is chosen.

A loft conversion is building work, and fire safety is usually the first thing checked. The officer, whether from the council or a registered building control approver, will look at the stair, the doors onto it and the protection of any room opening off it. The roof windows are drawn onto the same plans.

We fit to current Building Regulations, and any Building Control notification the job needs is ours to make. We work from the drawings your designer or architect supplies and fit the roof windows to them, positioning each unit as shown. Our guide to roof windows for loft conversions covers layout, while our Roof Window Installation hub covers the full range.

The sizing of the opening also matters to the cost. A bigger, taller unit changes the quote, which our guide to roof window fitting cost explains.

If you are unsure which category your house falls into, bring the question to the survey. We will tell you what we see, and your designer or Building Control body has the final say on fire safety.