Skylights & rooflights in Frampton Cotterell Pennant walls, village lofts and sunny back extensions

That difference explains why a roof window works so well on these houses. The wall windows cannot do much, because they are small and set into a deep reveal, and opening them gives a thin draught at best. A roof window above the bed changes the picture. It adds daylight from overhead, and the sash can open wide to release the heat that has gathered along the ceiling. Where the cottage already has a dormer, an opening unit beside it can set up a cross-flow, so air moves through the room instead of sitting in it. A dormer window and a roof window do different jobs: the dormer gives a view and headroom, the roof window gives overhead light and a high vent.

Matching the unit to the cottage

Some older homes here may be listed or lie in a conservation area, so the first step is finding out. The council in charge is South Gloucestershire, and the rooflight planning guide lists the questions to put to it. If a cottage is in a protected setting, the answer is a slim conservation rooflight, since it lies low and flush in the slope in the manner of a traditional slim iron rooflight. Many of them open on a hinge or a winding arm.

Rafters, slates and what lies beneath

Cottage roofs have had many hands on them. Stone slates, clay tiles and later concrete have each been used, sometimes on the same roof, and the timbers under them are often uneven. We assess the structure from inside the loft before proposing any size, because a wide window needs a rafter trimmed and framed, and in an old roof that is a job to do carefully. What a new opening requires, and when a replacement becomes notifiable, is covered in the rooflight Building Regulations guide.

Cottage owners sometimes assume the stone limits them to the tiniest unit, but the walls are not the issue; the roof is. A cottage that never had a rooflight can take a very small one and benefit from it. A single narrow window in a rear slope, set between two rafters, avoids most of the structural work. It will not change the house, but it gives the bedroom a place to breathe, and it keeps the cost sensible. If you later want a second, larger unit, the first one tells you how the room behaves, which is useful evidence before you spend more. For ideas on how much the work might cost, see our costs page.

Flat-roofed extensions and the greenhouse effect

On newer houses, and on older ones that have been extended, the rear kitchen is where heat builds. Big glazed doors let in the sun; a fixed rooflight lets in more. The result is bright, and by late afternoon it is also close. Exchanging a fixed unit for an opening one, or adding an opening unit next to it, relieves that without losing the daylight. An electric opening rooflight can be tied to a rain sensor, and the control can be a wall switch beside the door.