Skylight and rooflight fitting in Seven Sisters

The village of Seven Sisters, a community in its own right, stands in the Dulais Valley, in the heart of the South Wales Coalfield. The pit's name has its own story. David Evans, of the Evans-Bevan coal partnership, wanted to name it after his daughter Isabella Bevan, who cut the first sod at Bryn Dulais farm with a silver spade on Monday 11 March 1872. His own six sisters were at the ceremony, superstition got into the conversation, and he agreed to call the mine Seven Sisters.

The pit shaped the place. In 1923, 607 men worked there. A little of that history can still be seen: the pit head winding gear lies sunk in the ground beside the site of the old colliery, and five pairs of preserved railway sections show the scale of the operation. The railway still passes through, though the station was taken away and the line now carries freight only.

Housing followed the work. The first dwellings put up in the village were single-storey buildings for the miners, called Brick Row, and they are still standing. Before the 1930s, all the housing was for coal miners, brick workers and railway employees. That is the village's own record of its homes, and we stop there. We do not know the roof above any particular house until we have looked at it.

Seven Sisters is 17.62 miles from Swansea by road, to the north-east, comfortably within the reach of our survey visits. Within reach are Ystradgynlais and Banwen, and also Abercraf and Coelbren.

A low house changes the daylight question. Where the roof space above the ceiling is shallow, a sun tunnel can be an easier route for light than a roof window, since the tube between dome and ceiling has little distance to cover. Where the roof space has been fitted out as a room, a roof window lights it directly. Treat both as general patterns until the roof itself has been seen.

Houses in mining villages of that era were often built close together, in rows. A tight row has party walls on both sides, so the roof is the only place left to bring daylight in from above, and the front and rear slopes are usually the only slopes there are. Where a roof window can go depends on which slope has clear room, and a visit shows that.

Take the middle of a single-storey row house: a hallway or a back kitchen with walls all round and no window of its own. A sun tunnel suits that spot well. Up top sits a small dome; below it a mirrored tube drops the light to a diffuser in the ceiling. In drizzle the dome sheds the water at once, and the hall beneath gets an even grey-white light.

A kitchen at the back wants more glass. If it sits under a pitched slope, a roof window goes into the slope, level with the slates or tiles. If a rear addition has a flat roof, the options are a roof lantern with pitched glass, or a kerbed flat roof rooflight with nothing between it and the sky. A rooflight in Wales should reach 2.2 W/m²K under Approved Document L (Wales), and VELUX says its flat glass rooflights come in double or triple glazing, which helps with warmth and with sound.

The bathroom is where steam does its worst, because vapour climbs straight to the roof. A window there needs a sash that opens, and an extractor that carries on after the shower is off. On its solar and electric models VELUX fits a sensor that closes the sash when rain begins, so the room is not left open to the weather. Our page on electric opening rooflights explains the motor and the controls.

Glass low down, or close to people, calls for a thought about breakage. VELUX lists laminated safety glazing among its options, with an inner pane that holds together if it breaks. Which glazing a given window can take depends on the model.

Some roofs already carry a unit that has given up. Cloudiness between the two panes normally points to a failed sealed unit, and replacing misted rooflights is part of our work alongside new fittings.

A word on the dome itself: a size that suits a hall may not suit a stairwell, and the length of the tube depends on the distance between roof and ceiling. That distance is measured at the survey, because it cannot be read reliably from the street.

Planning for a Seven Sisters address goes to Neath Port Talbot Council. Seven Sisters sits outside the Gower AONB boundary, so that designation has no say in a job here. Whether a new rooflight can go in without an application comes down to the house and its roof, and the conditions are set down in our guide to planning permission for skylights in Wales. Read it before you spend anything, and put the question to the council if you are unsure which side of a condition your roof falls.

Not every home begins on equal terms. A flat or maisonette falls outside the householder permitted development rules altogether, and a house can lose its rights when the council makes an Article 4 direction, or when its first planning permission came with a condition removing them. A listed house needs listed building consent for any change that touches its special interest, and that application is made to the council as well.

A lantern normally rises high on its upstand, which is why fitting one over an old flat roof normally means a planning application. A lantern that belongs to a new extension is a separate case, and we confirm it with the council.

Building Regulations run alongside planning as their own track. Expect approval to be required for a new rooflight, since the roof has to be opened and must take the unit's weight. A like-for-like swap still counts as building work. Where the work is notifiable, we handle the Building Regulations notification with local authority building control or a registered building control approver.

Everything begins with the survey. The order is a free survey, a fixed written quote, then the work, and a 10-year workmanship guarantee in writing at the end of it. Ask for a survey, or call 01792 929062.