Castleford skylights and rooflights for rear extensions and estate bungalows

Where it should sit on the roof

The lantern goes above the zone of the floor that the doors reach least, usually the dining table or the island. We check that position against the roof joists, the line of the old house wall and any downpipe or vent that has to stay where it is.

Height and permission

Planning decisions for Castleford sit with Wakefield Council, and a lantern stands well clear of the roof surface, so the council needs asking unless the permission granted for the extension already took the lantern into account; the conditions can be found on the planning permission and Building Regulations page. We tell Building Control about the lantern opening ourselves.

The kerb under the glass

The lantern stands on a timber kerb built up from the roof deck, and the roofing membrane is turned up the kerb on every side. Whether the deck is covered in felt, rubber sheet or fibreglass, the turn-up is detailed to suit that material. We also confirm that the joists below can carry the glass, because a lantern weighs more than a flat pane of the same footprint.

Choosing the frame

Aluminium frames have slimmer bars and are stronger, and uPVC frames cost less. The two frames are compared under aluminium or uPVC for a roof lantern, and the way footprint and height are given is explained in roof lantern sizes.

Summer sun

A glass roof over a kitchen gathers the afternoon heat. Glass with a solar-control coat keeps part of it out, and the choices are gone through under whether rooflights make a room too hot.

Under the lantern

Inside, the underside of the kerb is lined and plastered so the lantern sits in a clean white well. The lining slopes slightly outward, which lets the light spread over the table below instead of dropping in a narrow column.

On the fitting day

The kerb goes up and the membrane is turned up it, the lantern is lifted into place and sealed, the ceiling opening is trimmed and plastered.

What a sun tunnel is

A dome on the roof gathers daylight, a reflective tube carries it down, and a diffuser in the ceiling spreads it into the room. It needs no wall, so it suits a room that only has roof above it.

Straight runs and bends

Light is lost at every reflection, so a rigid tube with few bends serves a long drop better than a flexible tube does. Where the roof is directly over the room we use the shortest, straightest run, and where the bathroom sits off to one side of the ridge line we work out whether an angled section is worth it. The trade-off is explained in rigid or flexible sun tunnel routes.

Setting the dome in concrete tile

Concrete tiles interlock in a profile, and the dome's flashing is shaped to follow it. A few tiles are lifted around the position of the dome and laid back over the flashing so rain runs off the slope. The dome's footprint is narrow enough to sit within the rafter spacing in the ordinary case. If the tube cannot miss a rafter, the framing round it is altered and we treat the job as structural work.

The ceiling end

Under the tube, the diffuser is fixed to the bathroom ceiling and sealed, so steam from the room does not run up into the loft. That seal matters in any bathroom, and we leave the diffuser as neat as the ceiling around it.

Choosing the dome position

The dome should face the sky as openly as the slope allows, with no chimney or neighbouring ridge shading it for much of the day. We look at the tiles above the room, at what stands to the south of them, and at how the tube can leave the loft floor without crossing the hatch. A position that looks right from inside the bathroom is checked against what is above it.

A hall as well

A hall with a loft above it is also a good candidate, and a bungalow often has one where the front door opens straight into a passage with doors on both sides. Where the loft has been boarded as a room, a roof window may light the space better than a tube, and the cases are set out in sun tunnel or roof window for a bungalow loft.

Taking the old dome out

The old dome is lifted off its kerb and the kerb is looked over. A timber kerb that has stayed dry can be re-used, and a soft or split one is rebuilt. The roof covering round it is lifted back, so we can see whether it still lies tight against the upstand.

The new rooflight

A flat rooflight is a glazed panel in a frame on the kerb, and it can be fixed or opening. In a utility room, an opening unit also lets steam out of the room. Part L caps the U-value of a replacement rooflight at 2.2 W/m²K, so a modern unit holds in more warmth than an old single skin of plastic.

Same size or larger

A bigger opening is tempting once the old dome is out, because the room is small and the roof is flat. Enlarging the opening means new framing, so the joists are looked at first. The guide to fitting a larger rooflight in place of the old one goes through what changes.

Matching the roof covering

The roof covering is the part that keeps the rain out, so it is turned up the new kerb in the same material as the rest of the roof. We match what is already there and do not mix felt, rubber and fibreglass on one roof, since each takes its own turn-up detail.

Fixed or opening

In a utility room, the washing machine and the dryer put steam into the air, and an opening rooflight gives it somewhere to go. A fixed pane suits a lean-to used as a store, where the aim is light and nothing else. Either type takes the same kerb, so the choice can be made late.

Under the opening

The lining of the opening is renewed in plasterboard and plastered, and the plaster is left ready to paint as quoted. The room keeps its ceiling height and gains a clear pane where the cloudy dome was.