Rooflights and skylights in Bassingbourn

That consistency has a structural side. Housing from the middle of the twentieth century onward is the era in which prefabricated trussed rafters became standard, and a truss cannot be cut into without an engineer redesigning how the roof carries its load. A roof window sized to sit between two trusses goes in with no structural work at all; a wider opening across a truss means a trimmed structure agreed in advance and carried through Building Regulations. We check the loft on every one of these houses before we draw a size, rather than assume the roof will take whatever the room seems to want.

Ceiling heights in this housing tend to be modest and the rooms square rather than long, which suits a single roof window over a landing or a small bedroom better than a large lantern. Where a bathroom or hallway sits in the middle of the plan with no outside wall at all, a compact sun tunnel reaches between the trusses and lights it from a section of roof that would otherwise do nothing for the room below. Owners converting a loft in this housing usually want two smaller openings either side of a truss rather than one wide one, which keeps the structure simple and lights the room from both ends.

The roof covering on this housing is usually a plain concrete or clay tile laid at a gentle pitch, chosen originally for cost and speed rather than character, and it takes a standard roof window comfortably once the pitch has been measured against the manufacturer's range. Where a house has since had its loft boarded out as a home office or a spare bedroom, the existing water tank and pipework often sit exactly where the best opening would go, so we plan the position around what is already up there rather than moving tanks unnecessarily.

Some of these houses have gained a single-storey rear extension over the years, sometimes with a flat roof, sometimes tucked under a catslide. That rear roof is usually the best place to bring in daylight, because an opening overhead sees far more open sky than a window in a wall ever will, especially where the next-door garden or an outbuilding closes off the view sideways. Where the roof above the original house is the one being opened rather than an extension, the older rafters are rarely on a tidy spacing, and a conservation-style rooflight with a slim central bar sits low into a plain tile or slate roof without looking like a modern box dropped onto an old one.

We do not assume a conservation designation for any particular street here. Some of the older lanes around the church may fall inside a conservation area and some may not, and the honest answer sits on the planning authority's own map rather than in a general description of the village, so we check it before recommending a product.

Room use in these older houses has usually changed several times over. A back bedroom becomes a home office, a scullery becomes a utility room, a loft that once held nothing but a cistern becomes a child's bedroom. Each change moves where the light needs to fall, so we ask what the room is for now rather than design around what the original builder had in mind.

Whichever route applies, the rooflight itself still has to satisfy Building Regulations, for its thermal performance, the structure around the opening and, near a boundary, fire spread. Our Building Regulations guide explains what is checked, and we handle the Building Control notification ourselves wherever the work is notifiable.

Outside, we check the compass direction of the slope in question and look at anything nearby, a neighbouring gable, a mature hedge, an outbuilding, that could shade it at particular hours. Inside the loft or above the extension ceiling, we look for trusses or older rafters, measure the pitch, and note the roof covering so the flashing detail is right from the start. Where a listed building or a conservation area might be involved, we check the position on the planning authority's own map before the light plan is drawn.

• The position, size and type of unit, chosen for the room and the slope
• The glass and any shading needed for that particular orientation
• The structural approach, including engineer input on trussed roofs
• Whether the work is notifiable, and how we handle that notification

Everything above goes into a written light plan alongside the quote, so you can see what you are paying for and why, before anything is cut. Our costs guide sets out the general factors that affect price. Every installation carries our 10-year workmanship guarantee. To arrange a visit, book a light survey or message us on WhatsApp, and see the fuller list of areas we cover around Cambridge.