Skylights for older village houses in Darfield, and rooflights for bathrooms and back bedrooms

Opening or fixed

An opening unit lets that air out. A handle or pole works a roof window, while an electric opening rooflight answers to a wall switch or handset, which suits a bathroom where a pole would be in the way beside the bath. Many models carry a sensor and shut themselves if rain lands on the glass. A fixed unit still brings light, and a small extractor fan can deal with the steam.

Condensation on the glass

Any cold surface in a warm wet room will collect moisture. A sealed double- or triple-glazed unit with warm-edge spacers stays warmer on the inside than a single pane, so less condensation forms on it. A low U-value limits the warmth passing out through the glass, which keeps the inner pane from chilling. The frame matters too: a thermally broken frame keeps the cold from the room side.

Where in the bathroom

A unit is positioned to put light on the mirror and the washbasin, and not directly over the shower where it would be wetted constantly. In a room with a sloping ceiling the opening splays down to the plaster, and the light well is lined with a smooth, washable finish.

Getting through the ceiling

A bathroom ceiling in an older house is often lath and plaster, or plasterboard fixed to joists that run across the room. The opening is cut with the floor protected, the edges are tidied, and the light well's lining runs up to the frame in a finish that stands up to wet. Any pipework or cable in the roof space is checked before the cut, so that nothing is damaged on the way through.

Privacy

A rooflight in a pitched roof looks up at the sky. Nobody can see in from the ground, and a blind or frosted glazing handles the rare overlooking from a higher window. In a bathroom that makes it the most private way to add daylight.

What comes out and what stays

The old frame is released from the roof, along with the flashing around it. The timber opening stays where it is, since the rafters have already been trimmed round it. A new frame is set into the same gap, with new flashing laid in to suit the covering. Inside, the light well and the plastered reveal usually remain untouched, although the lining at the very top is renewed where the old frame was fixed.

Matching the size

Rooflights are made in standard sizes, and a replacement has to fit the existing opening. If the old unit is a VELUX, a label on the frame carries its size code, with the width in the letter and the height in the digits. A different make can be fitted if its size matches. Where no label survives, we measure the opening and name the unit and its size in the written quote.

Weathering the new frame

The flashing is the part that keeps water out, and it is laid in to suit the covering: a slate kit for a slate roof, a tile kit for a tiled one. Where the old flashing has corroded or lifted, that can explain a stain on the ceiling below. The new set is lapped under the covering above and over the covering below, so water runs round the frame and onto the roof. The tiles or slates beside it are re-laid tight against it.

A chance to improve the glass

Glazing has moved on a long way. A new sealed unit meets the current energy standard: a roof window must reach 1.4 W/m²K, or Window Energy Rating band B, and a rooflight 2.2 W/m²K. An old single-glazed unit will fall short of both, so the room below loses far less heat once it is replaced.

When the whole frame has to go

Sometimes the sealed unit alone cannot be changed, because the frame is rotted or the rooflight is an early design with no spare glass. Then the complete rooflight is replaced, and misted rooflight replacement sets out how that choice is made.

The slope matters

A slope that faces the afternoon sun delivers strong light and a good deal of heat on a bright day. A slope facing away gives softer light that changes little through the day, which is what most desk work wants. If the only option is a sunny slope, solar-control glazing and an internal or external blind keep it comfortable.

Which way the window opens

Centre-pivot frames swing on a midpoint pivot, which works over a desk or other furniture. Top-hung frames swing out from the upper edge and keep the head clear, which helps where the ceiling slopes low and people stand near the glass. Our roof window page covers both, and you can compare the coatings on energy efficient rooflights.

Blinds and control

A blind fitted to the frame cuts glare and heat when needed and leaves the room bright when it is not. Some blinds are cranked by hand; others run on a motor and are operated from the same remote as an electric opening unit. At the desk, a blind that lowers from the top of the glass shades the screen but leaves the lower part open for light.

Position over the desk

The best place for the unit is usually beside the desk and not directly above the screen, so the light falls across the work and not onto the monitor. A tall person at a standing desk wants the glass above head height. These points are settled on site when the position is marked out against the furniture.

Heat in summer, warmth in winter

The same glass that lets in summer sun also has to hold the heat in once autumn arrives. A unit with a low U-value and a warm-edge spacer does both jobs, and the blind handles the brightest days. Working in the room all year, you notice both ends of that range.

The planning side

A house roof window normally stays within permitted development provided it rises no higher than 150mm above the roof plane and stays under the ridge. The conditions are in our planning guide, and Barnsley Council can confirm a particular address.