Rooflights and skylights in Brighton, a city of terraces and protected streets

Brighton is about 22.9 road miles from Crawley, comfortably inside the thirty miles we cover, and it is part of the city of Brighton and Hove. The city became a unitary authority in 1997 and received city status in 2000, so one council handles most planning questions for a Brighton roof.

The setting shapes the job. Brighton lies between the South Downs and the English Channel, on chalk with layers of greensand and gault clay beneath. For a rooflight that is background rather than a foundation matter, but it explains why the place has such a mix of buildings: a sea-facing edge, a chalk hinterland and a hillside in between, all lived in by a district population that was estimated at 283,870 for 2017.

A second point catches people out. More than 40% of Brighton and Hove lies inside the South Downs National Park. Since 1 April 2012, planning applications and enforcement inside the park have been the responsibility of the South Downs National Park Authority, and the planning work is split between the two authorities. So a house on the northern edge of the city can answer to a different body from a terrace near the seafront. We do not assume which applies. The position is checked for your address before a quote is final.

Brighton and Hove has 34 conservation areas. Those in Brighton itself include Regency Square, Kemp Town, East Cliff, North Laine, Old Town, Montpelier and Clifton Hill, Valley Gardens, Queen's Park, Carlton Hill, Preston Park, Preston Village, Patcham, West Hill, Round Hill and College. That is a long list for one city, and it covers the seafront, the centre and several of the hills behind it.

Regency Square shows the scale of a single area. It was designated in 1973, extended in 1977 and again in 2005, and now covers 32.25 hectares. Boundaries drawn and redrawn over three decades do not always follow the lines a homeowner expects. One house can sit inside while the next door neighbour, across a rear lane, sits outside.

For that reason we never tell you from memory whether your home is protected. The status is checked for the address. The check is short paperwork done early, and it decides whether the job is a straightforward installation or one that needs an application first. Where protection does apply, the product changes too. A slim unit that lies flat with the covering is a different object from a raised lantern, and conservation rooflight installation sets out what that means in practice.

Many Brighton houses are built of a material that almost nobody else uses. Bungaroosh is a composite of flint, broken brick, pebbles and lime mortar, used almost exclusively in Brighton, Hove and coastal Sussex from the Regency period. It was usually covered with stucco or plaster, so you rarely see it, and a loft conversion can be the first time anyone finds out what the house is made of.

That matters for rooflights for a plain reason. Bungaroosh has poor water resistance, and it is prone to dampness and to crumbling when it dries out. A rooflight does not usually need an opening in the main walls. But a stair light, a parapet detail or a new dormer cheek can touch the top of a wall, and then the material counts. Lime mortar and rubble behave nothing like the clean brick of a newer house. A fixing that would sit well in a modern cavity wall can loosen in a mix of flint and broken brick.

So at survey we look at the roof edge, the parapet and the wall head, not only at the rafters. Where the wall is sound, the plan goes ahead as drawn. Where the lime has gone soft, the detail changes: the unit might be moved inward, or its upstand carried on the roof structure instead of the wall. We would rather change the plan than trust the masonry.

Terraces and villas ask different things of a rooflight. The first rule is to match the unit to the roof it lands in. A steep pitch takes a roof window. A low slope or flat roof takes a kerb-mounted unit. A wide kitchen extension might want a larger fixed pane, and a small landing wants something modest that simply lets the light drop in.

Size follows the room. A bedroom loft needs enough glass to feel bright without becoming a heat trap in July, and the trade is to balance glass area against summer heat. Position matters as much as size. A unit near the ridge draws warm air out, while one lower on the slope lights the floor. On a slim terrace roof, a single well-placed window often does more than two crammed in.

The seafront adds a small extra. Salt air is tough on cheap fixings and poor coatings, so we choose frames and flashings for the environment they will live in. That is ordinary specification, not a special product line.

These are the questions people ask first when they are thinking about a rooflight in this city. Each answer is general, and your address decides the detail.