Tiled roofs over Bishopthorpe's brick houses, bungalows and extensions, and the skylights and rooflights that light them

Roofs near the palace

The conservation area was designated in 1989 and takes in Main Street as well as the palace and its grounds. A rooflight on a rear slope, out of line of the road, makes the smallest change to what is seen.

Frames that sit low

On a tiled or slated roof in the conservation area we would put forward a conservation rooflight. It has a slim dark frame, often with a single glazing bar, and lies close to the covering so the roof keeps its line. One unit in the right place is easier to justify than several.

Checking the listing

Some houses in the old village are listed. Historic England's national list can be searched online by address. Listing is a separate hurdle: the consent that goes with it must be in place before a rooflight goes in, and it overrides what permitted development would allow. We look the address up before suggesting a unit.

Two houses in one street

Neighbouring houses can sit on opposite sides of a conservation-area boundary, so one needs more checks than the next. The boundary is looked up against the address and never guessed from the street name, since a line on a map can run between two front doors.

The streets beyond

Later streets of twentieth-century and newer houses lie away from the old centre. Where a house sits outside the conservation area, ordinary permitted development limits apply: the unit must not stand more than 150mm proud of the slope or rise above the highest part of the roof.

Replacing an existing unit

An older house may already carry a rooflight from a past loft conversion. A new unit in the same opening disturbs the roof far less than a fresh cut, though listing can bring consent even to that.

The lantern

A roof lantern is a pitched glazed structure standing on a kerb. It suits a wide room, since it lets light in from four sides and gives the ceiling a shape. Glazing bars on an aluminium frame can be thinner than those on uPVC, which matters across a wide span.

The flat rooflight

A flat roof rooflight is a low panel of glass on a kerb. It lights the middle of a narrower room without much show from outside, and it sits far lower than a lantern, though the kerb and unit together are still measured against the 150mm projection limit.

Planning

A lantern usually rises well beyond 150mm, so it often falls outside permitted development, and the answer is to ask the council or to have it covered by the extension's own permission. A lantern designed into the plans for a new extension is the easiest way to deal with that.

Where it lands over the room

The best place for a lantern is usually over the table or the island, because that is where people stand and sit. The roof structure beneath has to allow it, so the position is checked against the joists before it is fixed, and moved along a little if a joist sits in the way.

Covering and kerb

The flat roof may be EPDM rubber or GRP fibreglass, and each takes its own upstand detail round the kerb. The covering on your roof is noted first and the kerb is dressed to match.

The strip beside the old house

The original back wall of the house still stands inside the extension, and the strip along it is the part the glazed doors never reach. Placing the rooflight or lantern towards that side, rather than in the centre, lights the long end of the room more evenly.

Energy and overheating

A rooflight of this kind has a U-value limit of 2.2 W/m²K under Part L. Solar-control glass reduces the heat that comes in from a roof that faces the sun, and glass that opens lets hot air escape.

Above the garage room

A flat roof over a garage room takes a rooflight on a kerb as readily as an extension does. It can be placed over the middle of the room, where it lights desk or bed alike. A shallow pitched roof takes a roof window fitted into the slope.

A shower room with no outside wall

A sun tunnel suits a windowless shower room, as long as the roof lies directly above it. A tube runs through the roof space between rafters or joists, and a diffuser fits flush with the ceiling. Rigid tubing carries daylight further than flexible tubing, so a short straight run is best.

Which way the roof faces

A garage roof that faces south lets in strong sun in the afternoon, and one that faces north gives an even, cooler light. A desk or a bed benefits from the second kind, and a play area copes happily with the first. The orientation is noted so the glass can be matched to it.

Ventilation as well

A damp shower room needs air as well as light. An electric opening rooflight, worked by a switch or a remote, lets steam out through the roof, and some models close themselves when rain falls.

Joists under the garage roof

Flat garage roofs have joists that span the width of the building, and the opening is framed between two of them. The size of the unit is chosen to fit the gap, with trimmers carrying the load around it, so the roof structure is altered only where it must be.

Insulation after a conversion

A converted garage has often been insulated to a good standard, so the glass in the new rooflight should match it. A coated, multi-layer pane in a thermally broken frame stops the new opening becoming the cold spot in the roof.

Plasterboard that cuts cleanly

The reveal is lined, plastered and ready to decorate. A flat ceiling in a converted garage may be plasterboard on timber, and it cuts cleanly. The dust sheets go down before the cut, and the opening is lined and left ready for decoration. Because the room is often a single span, the new light well is short and the result looks like part of the ceiling.