Skylights for Victorian houses in Mirfield, and rooflights for the attic, stair and inner rooms

When the loft becomes a room

Turning a loft into a bedroom above two storeys brings in fire-safety rules about the way out, and a protected stair is what Approved Document B asks for there. A roof window does not stand in for it. Those rules belong to the conversion as a whole, and the survey is where we talk them through.

What suits the stair

• A roof window over the stairs and landing in a size matched to the width of the flight.
• A sun tunnel if the top landing is small and the run is straight.

Slate and the angle of the roof

The roof pitch in a Mirfield terrace can be steep, and we check it against the range of pitches the maker gives for the unit. The covering may be Welsh slate or the older stone slate, and the flashing is made to suit whichever is on the slope. The frame is fixed to the rafters, with trimmers across the opening to take the load.

Indoors, the light well is lined with plasterboard and plastered, so the reveal is clean. The stair keeps its dust sheets until the plaster is dry enough to be cleaned around.

Which way the glass should face

Mirfield stands on the valley side, and its roofs face every point of the compass. A slope that gets afternoon sun will light the stairs well in the evening, while a north-facing slope gives an even, cooler daylight through the day. Either works for a stair. We note which way the slope faces so the glazing can be chosen to suit, and a solar-control coating is on the table where the sun is strong.

What changes the answer

• Listing. Consent of a separate kind applies to a listed building, even for a unit on the back slope.
• A conservation area, particularly one with an Article 4 direction.
• A flat, a maisonette or a house split into flats, where rights for roof alterations do not apply and permission is usually needed.
• The side of the roof. A rear slope is far less visible.

The kind of unit that sits well

A conservation rooflight has a thin frame, usually black, and often a single central bar. It lies close to the roof, so the slates run right up to it, and from the road it looks like part of the roofing. For a unit that will be seen, it is a safer choice than a tall roof window frame.

Where the glass can face the back garden instead, a standard roof window can be the right choice.

Working on the older stone houses

Mirfield's older houses are built of local stone, with thick walls and roofs of stone slate or slate. The thickness of the wall means a window sits in a deep reveal, which shades the glass, so the rooms inside can be gloomy even where there is a window. A rooflight on the slope avoids that problem completely, since the roof has no reveal to shade it. Old timbers, though, need a careful look: some roofs have been altered over the years and the rafters are not always where a plan would put them.

Before anything is ordered

We check designation first, then settle the slope and the unit. If an application is needed, the size on the quote is what goes to the council, so the application and the order match. With the unit already chosen, the application is a short one, and the answer is in hand before anything is made.

Glass only, or the whole unit

If the frame is sound, a new sealed glazed unit can go into it. That keeps the opening, the flashing and the lining as they are. If the frame is warped, rotten or leaking, the whole rooflight comes out and a new one is fitted in the same opening, with a new flashing set into the slates.

We look at the frame, the flashing, the timbers around it and the ceiling lining, because a unit that has leaked for years can leave damp in the reveal.

A chance to do better

A modern replacement must meet current limits: a roof window 1.4 W/m²K or band B, a rooflight 2.2 W/m²K. Against an old single-glazed unit, that is a large step. The attic room underneath loses less heat, and the glass no longer drips onto the sill in winter. Warm-edge spacers, an argon fill between the panes and a low-emissivity coating on the glass all help a replacement unit in a Mirfield attic reach those figures.

Matching the old size

A like-for-like replacement keeps the roof as it was and changes little from the street. If a larger unit would help the room, that is a bigger step: the opening grows and the rafters are trimmed to suit, and the council may have to be consulted. The quote states which of the two you are getting, so that choice is made on paper before any work starts.

Reading the old unit

Before any quote, we look at the frame from below and the flashing from outside. We check the lining for stains, press the timbers around the opening to see whether they are sound, and measure the opening so a replacement can be matched. If the unit is a VELUX, the code on the label in the frame tells us its size, and the matching replacement can be ordered from that.

Access to an attic

Attic rooflights sit high, and the room beneath is often small with sloping walls. Dust sheets go down over the floor and furniture, and the old unit is lowered out through the house. The room is left clean and the plaster around the reveal is made good.