Skylights for older terraced houses in Cudworth, and rooflights for the rooms in the middle

Rooms the roof can serve

The upstairs centre room of a terrace, often a second bedroom or a box room, sits right under the roof slope and is the easiest to light. An opening in the slope above it, glazed as a roof window, brings daylight where the side walls are party walls and the only window is at one end. Skylight installation here is a matter of framing between two rafters and flashing to the covering.

The landing is next. If the stair is open to the roof, an opening above it, whether a roof window or a tunnel, sends light down the flight, and the hall at the bottom gains from it.

Rooms it cannot reach directly

The ground-floor centre room of a terrace has a bedroom above it, and a rooflight cannot pass through a bedroom. Options there are different: a glazed door or an internal window into the next room, or a rear extension with a roof of its own. Where an extension adds a kitchen at the back, its flat roof can take a flat roof rooflight, and the daylight reaches the kitchen and the dining space beside it.

Brightening the stair on the way

The stair of an older terrace usually rises between two solid walls, with a small window high up at the top. Lit from the roof, the flight takes daylight down its whole length. A roof window over the top landing sends light along the stair, and a sun tunnel does the same on a smaller scale where the loft above is still open and untouched.

A loft being converted

Where the roof space is being turned into a room, roof windows are the main source of daylight, and the number and position are worked out with the layout. Our roof window page explains the opening types, and the planning rules are in our planning guide.

Terraces share walls, so the position of the opening is kept clear of the party wall and of any shared chimney breast that rises through the slope.

Why do both at once

A rooflight needs a kerb, which is a timber upstand around the opening, and the roof covering has to be dressed up that kerb in one piece. Cutting into a covering that has years of wear left is possible, but the new junction sits among old material. Re-covering and fitting together means the whole roof is weathered by one hand to one detail.

Choosing the covering

Three coverings are common on flat roofs. Felt is laid in layers and is the traditional choice. EPDM is a single sheet of rubber with few seams. GRP is fibreglass laid wet and cured in place, so it forms one continuous skin. Each takes its own upstand and edge detail, and the rooflight is fitted to suit whichever you choose.

Keeping the room usable during the work

A flat-roof job is short compared with a loft conversion, but the kitchen below is open to the weather while the covering is off. We cover the opening with a temporary weatherproof sheet at the end of every working day, and the room is cleared before we start so the units and floor stay dry.

Looking at what is underneath

Before any opening is cut, we look at the deck and the joists. Water that has been getting in can have softened timber, and a rooflight needs sound joists on each side of the opening. If the timber is damaged, the affected length is renewed as part of the work.

Planning the daylight

On a small rear extension, one rooflight over the middle of the room is usually enough. Placing it over the cooking end lights the worktops; placing it over the dining end lights the table. An electric opening rooflight adds fresh air as well, and a switch on the wall opens it without a pole.

Placing the windows

A roof window needs clean roof covering around it and a clear length of rafter. In a conversion the windows are placed so that people can stand up near them and a bed or desk can sit below them. Centre-pivot frames swing on a pivot at their midpoint, so a bed or desk can stand beneath the sash. Top-hung frames swing out from the upper edge, which keeps the opening clear of the head.

Escape from the new room

Approved Document B sets the escape rule. Only a storey within 4.5m of the ground can rely on an escape window, measured from the floor of that storey. Rooms in a converted loft over two storeys sit higher than that, so the way out is a protected stair down to the front door. The roof window brings light and air, and the stair is the route out. A bungalow loft is a different case: its roof windows can act as escape windows.

Light for the stair of the new floor

The new stair to a converted loft takes up space on the floor below, and it often cuts across the landing. A roof window over the stairhead keeps the flight bright, so the move upstairs does not take daylight out of the landing. In a terrace, where the landing is already short of windows, that matters more than it would in a detached house.

Sizes that fit the rafters

Roof windows come in standard sizes, and VELUX gives its sizes in a code whose letter shows the width and whose digits show the height. Rafter spacing in an older roof is not always regular, so the size that fits is checked on site and named in the written quote.

Daylight for the room you already have

Not every Cudworth household wants a full conversion. A loft used only for storage can take a single roof window that turns it into somewhere to work or pursue a hobby, without putting in a stair or new floor. We would look at the head height under the ridge before suggesting a position, since a window set where nobody can stand beneath it wastes the daylight.

Living in the house during the conversion

A conversion takes weeks, and the roof windows are one part of it. We fit the windows and weather them early in the programme, so that the shell is watertight while the other trades work inside.