Skylights and rooflights for village houses in Brampton and the extensions built onto them

What a lantern is

A lantern is a glazed structure with pitched sides, standing on a kerb or upstand above a flat roof. It rises above the roof line, so it is seen from the garden and from the first-floor windows of the house. It is made with aluminium or uPVC bars, and the choice between them is practical rather than a matter of looks.

Frames and glass

Aluminium makes the slimmer and stronger frame, and uPVC makes the cheaper one. The glass is double or triple glazed, and thermally broken frames with warm-edge spacers help the unit hold its heat. A rooflight, a lantern included, has to reach a U-value of 2.2 W/m²K under Part L for a new or replacement element.

Planning for a lantern

Because a lantern generally rises beyond 150mm, it often sits outside permitted development, and Rotherham Council, or the extension's own planning permission, is where the answer comes from; the planning guide sets out the limit.

A lantern or a flat rooflight over a deep room

A lantern gives the ceiling height and a pitched roof of glass, while a flat roof rooflight lies lower and needs less depth in the roof build-up. A deep kitchen-diner can take either, and a long, narrow room sometimes takes two flat rooflights in a line where one lantern would sit awkwardly. The ceiling height inside and the look from the garden usually settle it.

Agreeing the kerb with the builder

When the extension is still being built, the height and size of the kerb are agreed before the roof covering is laid. Sizes are quoted either to the inner face or to the outer face of the kerb, depending on the maker, and the roof-deck opening is cut accordingly. A kerb that is a little out of square is hard to put right once the covering is down.

Weathering the base of the lantern

The covering is dressed up the outer face of the kerb to make the upstand, and a flashing or cap closes the join under the lantern frame. Which detail suits depends on whether the roof is felt, EPDM or GRP. The lantern is not fixed down until the upstand is complete, so the weathering is finished from the roof side first.

Inside the kitchen

The lantern shows from below as a sloping glazed ceiling with a lined kerb around it. The lining is plastered and decorated to match the ceiling, so the edge of the opening reads as part of the room.

What the glass is

The panel is usually laminated and toughened glass in a frame, made by a maker who rates it for foot traffic. We follow the maker's rating for the use intended, and we do not quote load figures here, since they belong to the specific product.

Where it goes

A walk-on panel suits a roof terrace, a balcony or a floor above a lower room. In a floor it lights the room underneath. The structure beneath is checked first, because the opening has to be framed to carry the surrounding surface.

How the opening is framed in the deck

The joists of a flat roof run one way, and the opening is framed between a pair of them with a timber trimmer at each end. That frame has to carry the panel and the people standing on the surface around it. Cutting a joist makes the job structural, which we notify, and the panel size is chosen with the joist spacing in mind. Our walk-on rooflight page sets out the product in more detail.

Keeping the weather out at the edge

The roof covering is turned up to the panel's frame and sealed. Felt, EPDM and GRP are each detailed in their own way, so the existing covering matters before a panel is chosen.

Light arriving from straight overhead

Daylight comes through a walk-on panel from directly above, so the room underneath is lit from its ceiling. A utility room, a stair or a small study under a terrace gains from that. Nothing is lost on the surface above, because the panel is flush with it.

Planning for a roof terrace

Using a flat roof as a terrace raises its own planning questions, and Rotherham Council is the place to ask; our planning guide covers what applies to a rooflight in the same roof.

What gets looked at

The kerb is checked for rot and movement, and the covering is checked where it turns up the sides. If both are sound, a new unit can sit on the existing kerb with a fresh weathering detail at the top. If the kerb is soft or the upstand has split, those parts are renewed so the new rooflight sits on a sound base.

Sealed unit or whole rooflight

A fogged unit has a failed edge seal, and the moisture between the panes cannot be removed by wiping. A new glazed unit can go into a sound frame. With a worn frame or single glazing, a complete new rooflight is the sounder choice.

Taking the measurements

An extension rooflight is measured on the roof itself, with a tape across the kerb at the top and at the corners. The new unit has to suit the kerb it will sit on, so the kerb is measured on the roof rather than from the old rooflight. The replacement is sized from the kerb itself, because makers differ over whether their stated sizes are taken inside or outside the kerb. A unit a little smaller than the kerb leaves room for the flashing to dress round it.

Better glass in the same opening

A replacement rooflight has to meet 2.2 W/m²K, which an old single-glazed unit will not. Double or triple glazing plus a low-emissivity coating reaches it, so the room below keeps more of its heat.

Working over a room in use

The room under an extension rooflight is usually a kitchen or a dining room, and it stays in use. Work from the roof side comes first, with a temporary cover over the opening whenever the old unit is out, so the room stays dry. Inside, the table and worktops are covered before any cutting happens.

The finish inside

The old reveal is cleaned and the plaster is finished where the new frame sits a little differently. Floors are sheeted first, and the room is cleaned when the work is done.