Horbury skylights and rooflights for the town's older stone houses and later estates

The listing is checked first

A listed Horbury house needs listed building consent before even a small new rooflight goes in, and permitted development makes no difference to that. If an older Horbury house turns out to be listed, the plan changes from a quick fit to an application, so the status is looked up before a unit is chosen. What an application involves is set out in listed building consent for a rooflight.

Which side of the ridge faces the road

On an older street the slope that faces the road matters most. A unit on the rear slope barely shows from the pavement, and a stairwell or an attic room can be lit from either slope. Choosing the rear slope where the room allows it is the easiest way to keep the roof line as it was. Where both slopes are in sight, as on a corner house, the useful question is which slope already has chimneys or roof windows breaking it up, because a new unit that lines up with them looks like part of the pattern.

What a conservation rooflight looks like

Where the roof is slate in a protected street, a conservation rooflight is the unit officers often ask for. The frame is slim and normally black, there is often one glazing bar running down the centre, and the whole unit sits close to the slates instead of standing proud of them. From the street it looks like part of the roofline rather than an addition to it.

Limits that apply to any house

Under permitted development a rooflight must stand out no further than 150mm from the roof slope, and it must not stand above the top of the roof. Both limits are easy to meet with a roof window or a conservation rooflight, because those lie close to the slope. If the work does need an application, the council is asked about one named unit of a known size, which keeps the discussion short.

When another floor sits above the bathroom

On a lower floor, a rooflight cannot reach the room without passing through the floor above. A tube would have to run through a bedroom or a cupboard, which is rarely worth the loss of space. For a bathroom like that, the question moves to the nearest part of the house that does reach the roof, and sometimes the better gain is the landing outside it. Light from a roof window over the landing then spills through a glazed door panel.

Bathroom steam and the unit above it

A bathroom produces steam, so a roof window over a bath or shower is chosen with a frame that handles damp. Fitting a rooflight does not replace the extractor fan, and the two work together. A sun tunnel's diffuser is sealed, so steam does not travel up the tube into the loft.

Obscured glass is the usual choice where the room is overlooked by neighbouring bedroom windows, and a roof window set high on the slope is rarely overlooked at all. Whichever unit is used, the ceiling opening is plastered and finished neatly so the bathroom is ready to tile or paint around it. A top-floor bathroom with a sloping ceiling gains the most from a roof window, because the glass can be set over the bath or basin where the light is wanted, and the lining of the opening can be angled to throw it across the room.

The kerb under the old rooflight

The weather-tightness lives in the kerb and its flashing. Where the kerb is sound and the covering up its sides is intact, it is kept. Where it has softened or the covering has lifted, that part is rebuilt before the new unit goes on, because a new rooflight on a tired kerb would soon let the same water in. A kerb that sits too low for the roof covering is raised to the correct height at the same time.

A better unit in the same hole

Kitchens in a rear wing are also where a rooflight sees the most condensation, since steam from the hob rises straight to the glass. A unit built with warm-edge spacers and good seals keeps its inner pane warmer, which reduces the condensation that forms on it.

The replacement is a chance to improve on the old one. Double glazing, a low-emissivity coating and a warm-edge spacer lose less heat than the single glazing found in older rooflights, and a replacement rooflight must meet the Part L limit of 2.2 W/m²K. If the old unit is a roof window, the limit is 1.4 W/m²K or band B. For matching the new unit to the old one, see like-for-like roof window replacement.

What the kitchen sees on the day

On fitting day the old unit is lifted out and the new one fitted, with a temporary cover over the opening if the weather turns. Worktops and units under the opening are covered, and the debris goes out through the roof rather than through the house.