Rooflights and skylights in Coulsdon

Coulsdon was Surrey until 1965, and it still feels like the edge of somewhere. The ground is chalk, the valleys are dry, and the houses arrived in waves once trains made the commute possible.

The railway station opened in 1889, and the bulk of the suburban housing dates from between 1890 and 1970. That span covers a lot of roof types. Late Victorian and Edwardian houses have cut timber rafters and purlins. The interwar semis have lighter softwood, often with a hipped roof and a shallow attic. Postwar houses from the 1950s and 1960s tend towards simpler frames and, in places, engineered trusses.

The 2021 Census counted 25,530 residents across the two wards, Coulsdon Town and Old Coulsdon. That is a sizeable community living in houses that were built for a different idea of a loft. Attics were storage. Now they are bedrooms, offices and playrooms, and the roof glazing is what makes them pleasant or not.

The age of the house tells us what is under the tiles before we lift one. That matters, because the rafters decide where an opening can go and how much of the structure has to be trimmed.

In an Edwardian or late Victorian house, the roof is usually framed from substantial timbers. There is room to work, and a roof window can be set between rafters or a rafter can be trimmed with a proper header. The loft is often tall enough for a real room. A larger unit can suit it, provided the structure round the opening is strengthened to match.

The interwar semi is a natural candidate for a conversion. The roof is shallower in section, and the space is tighter. A roof window set a little higher in the slope gives standing light without taking headroom from the bed or the desk. Where the pitch is low, a flat-roof-style rooflight on a dormer or a rear extension may do more than a roof window can.

Old Coulsdon is the southernmost settlement in Greater London, and Rickman Hill Park is described as the highest public park in London, at 155 metres above sea level. A rooflight up here meets weather that a valley house does not.

Height means exposure. Wind drives rain harder across a roof on the top of a ridge, and a window on the windward slope takes the brunt of it. That makes the detail round the frame more important than the glass. The flashing has to lap properly over the tile, the upstand has to be high enough to shed water off the glass, and the frame has to sit on a sound, insulated kerb.

Rain on glass is also a sound. A flat rooflight over a kitchen extension can make a room noisy in a downpour, because raindrops strike a hard, resonant surface. The remedy uses the same means as for the train. A laminated pane damps the impact, a deeper frame gives the drops less to drum on, and the cavity is sized to break the ring. Our page on reducing rain noise under a flat rooflight explains each step.

Each of Coulsdon's house types tends to suggest a product. Three examples show how the choice follows the room.

A rear extension on a 1930s semi is usually flat-roofed. A rooflight set into it gives the room daylight deep from the garden door. A large fixed unit on a low upstand can work, and a roof lantern adds height and a more traditional shape. Our flat roof rooflight installation and roof lantern installation pages explain the difference in use.

A loft bedroom on a Victorian villa calls for a roof window. It should be large enough to admit daylight and sit low enough to open easily. Ventilation matters too, because a bedroom under the tiles can be stuffy in summer. An opening unit, manual or electric, gives a controlled way to clear the air. Our page on electric and opening rooflight installation covers those.

These are the questions a Coulsdon address tends to raise, each answered for the town.