Skylights and rooflights for bungalows and semis in Dodworth and the streets around it

Crossing the loft

Bungalow roofs from the later part of the last century are often framed from trussed rafters, which are engineered timbers that carry the roof's load in a set pattern. They are not cut to suit a fitting. The tube is therefore placed between two trusses, and we find where they sit from the loft before choosing the position of the dome.

Rigid or flexible

A straight run uses a rigid tube, which passes on more daylight. A bend, or an offset to dodge a truss, takes a short flexible length. The comparison of rigid and flexible tube routes sets out the choice. Insulation is wrapped around the tube where it passes through the cold loft, which stops the tube sweating.

Roof window or tunnel

A roof window is the larger of the two options, and it needs a light well. A tunnel suits a narrow hall, since a window over it would lose most of its glass to the walls on either side. The comparison of tunnels and roof windows weighs the two.

The tiles at the dome

A bungalow roof in concrete tile gets a collar made for the tile profile, set into the course and lapped so that rain runs off it onto the tiles below. The dome stands only a little proud of the roof. Barnsley Council is the authority for any planning question, and the rules for rooflights on houses cover flats and listed buildings, where the answer changes.

Why a hall suits a tunnel

A hall has no furniture to shade and no bed to disturb, and people pass through it all day. Daylight from a single diffuser reaches every door, so the bedrooms, the bathroom and the living room all gain a little when their doors are open. That makes the hall a better candidate than any one room off it.

Inside the hall

The diffuser fits flush with the ceiling, and the plasterboard around it is finished to match the ceiling. If a light fitting hangs in the hall already, the two can sit side by side, so the passage is lit by day from the roof and by night from the fitting.

What an escape window has to do

Approved Document B covers means of escape. A window that serves as an escape route must open wide enough for a person to climb through, and it must sit low enough to reach. It serves only rooms within 4.5m of ground level, measured to the floor of the room. A bungalow's roof room falls inside that height, so a roof window can do the job. The document gives the minimum opening sizes, and they are checked against the unit you choose.

Two storeys is different

A two-storey house with a new room in the roof is another case. The new room has to be reached by a protected stair, and an escape window cannot replace one. A bungalow avoids the problem.

Which sash for the bedroom

A top-hung sash hangs from hinges at the head and swings out, which keeps the opening clear of the head and makes it easier to climb through. A centre-pivot sash rotates and sits better above a bed or a desk. Which you choose depends on how the room is laid out. Planning for either is covered in the guide to roof window permission.

Headroom under the slope

A roof room is often tight, with the ceiling following the rafters. A window set too low in the slope can leave the sill at knee height, and one set too high is out of reach. We mark the sill position from inside the room, standing at the height of whoever uses it.

Light as well as a way out

The same window does two jobs, and the daily one is lighting a room that otherwise depends on the dormer. A pair of units gives balanced light across a longer room. A larger bedroom under the slope may take two smaller windows better than one big one, because each sits between its own pair of rafters.

The roof window section sets out the sizes and options for a room like this. Spacing between windows on the same slope is worth planning, because each unit needs clear slate or tile on every side.

One bay or several

Before any of that, the roof is opened a little so the joists can be measured. What the drawings say and what is on the roof do not always match in an extension of some age, so the real spacing is the one we use.

An opening that fits in one gap between joists is the simple case. The kerb is built around it, the covering is lapped up the kerb, and the rooflight is set on top. Wider than that, and one or more joists are cut and carried on a doubled joist on each side. That is structural work, and we frame it properly before the covering goes back.

Reading the maker's sizes

A maker's size list may refer to the inside of the kerb or to its outside, depending on the maker. That difference affects whether a unit fits the opening you have, and the written quote names the exact unit. The flat rooflight sizes page goes through the common ones.

A lantern in place of a rooflight

A roof lantern stands well above the roof, and it usually rises past the 150mm that permitted development allows. It may need the council's permission, or the extension's planning permission may already cover it. Barnsley Council can say which. The roof lantern sizes guide shows the range.

The room beneath

A bigger opening gives more daylight, but a south-facing flat rooflight over a kitchen can raise the heat on a sunny day. Solar-control glass is the answer, and so is leaving a little shade. The overheating guide explains how.

The beam and the cabling

A flat roof over a modern extension often carries a steel beam above the patio doors, with joists running back from it. Downlights and cables sit in the ceiling below. We check both from the room and from the roof, because the opening has to miss the beam and the cabling, or the cabling has to move.

Dropping the ceiling

A bedroom or bathroom with a flat roof above it will take the same treatment, with a kerb on the roof and a splayed lining below.

The ceiling around the opening is lined with a splayed upstand so the light spreads into the room. A deeper roof build-up gives a deeper well, and the plasterboard is finished so that the edge looks the same as the rest of the ceiling.