Which rooflight gives access to a flat roof?

Hinged access rooflights

A hinged access rooflight is a glazed lid on a kerb, with hinges along one edge and gas struts or a chain to hold it open. It is the compact choice, and it fits above a landing, a loft ladder or a narrow stair where the opening cannot be large. The clear opening is set by the size of the unit, so the first thing we do is measure what you need to pass through.

Hand opening is usual on the smaller sizes, with a pole or a handle. A motor suits a larger lid, a high ceiling or a user who cannot lift a sash, and adds a switch or remote to the quote.

Sliding box rooflights

A sliding box rooflight has a glazed lid that runs along rails over a fixed upstand, so the opening is wide and you step out at the stair head. It suits a fixed stair to a roof terrace, where you want to walk out upright. It is the larger product, and the price and the structure around it reflect that.

The motor is usual on a sliding unit because the sash is heavy, and the controls and the rain sensor are as important as the glass. Our answer on how a rain sensor works covers the point that matters if the lid is left open.

The two, side by side

The sliding box rooflight can look much like a small lantern when it is closed. Our guide to walk-on rooflights covers glass you can stand on, which is a different product from a lid you open and climb through.

The stair or ladder below

The opening is only half of the access; the other half is how you reach it. A fixed ladder or a loft ladder suits a hinged unit and an occasional visit. Regular access to a terrace or a green roof needs a proper stair, and the stair head and the opening have to line up.

For that reason the room underneath gets measured at the survey along with the roof. A rooflight set to the roof drawings can land awkwardly over a landing, and we check the headroom, the stair line and where the person climbing will stand. Anyone using the opening to reach a roof edge should have a guard rail or an edge protection plan, which is a point for the roof designer to settle.

• Clear opening sized to the people using it
• Stair or ladder lined up with the opening
• Edge protection considered for the roof

Weather, security and glass

An access lid is opened more often than a fixed rooflight, so the seals and the hinges see more use. Ask what the gasket is made of and how the lid is held against wind when open, because a gust can catch a large sash. Gas struts and stays differ between makers, and we put the details for each unit in the same rows on the quote.

Security matters on a lid that can be climbed through. Locks on the sash, a laminated inner pane and a lock that works from inside only are the usual measures, and we list which units include them. Glass options follow the same pattern as other rooflights: double glazing as the base, with solar control or self-cleaning coatings as extras that raise the price.

Hand or motor, and what the roof can take

A lid that needs a motor to lift is worth thinking about early. The cable route, the switch position and the rain closing all follow from it. Our guide to manual and electric rooflights sets out the trade between the two, and the cost answer explains what a motor adds.

Where a new opening is formed in a flat roof, that is building work, and a swap of the complete rooflight, frame and glass must also be notified under the Building Regulations. Notification to Building Control comes from us whenever the job calls for it. The upstand and the joists around the opening are checked at the survey; our guide to flat rooflight upstands explains how the kerb is built.

Planning permission may or may not be needed, depending on the house. We look at your address, but the council makes the decision; our rooflight planning guide sets out the conditions. Book a free survey and we will price a hinged and a sliding option side by side.