Rooflight and skylight installation in Weeley

Cut or trussed, the question that sets the price

Establish it before asking anyone for a quotation. It takes two minutes with a torch and it decides more about the cost than the choice of unit does.

Rafters running from eaves to ridge with a horizontal purlin partway up and clear space between them is a traditional cut roof. Forming or widening an opening is ordinary carpentry, wide rooflights are possible, and the loft is convertible.

A repeating pattern of triangular frames with diagonal members crossing the middle of the space, joined by flat pressed steel plates, is trussed rafters. Rafter, ceiling tie and webs act as one engineered unit, and cutting any member sends load somewhere it was not designed to go.

With trusses at the usual 600mm centres, a unit narrow enough to sit between two of them needs no structural work at all. Anything wider needs a structural trimmer designed by an engineer, which is routine and which is the point at which the price steps up. It is also why a trussed loft cannot be converted without replacing the roof structure.

Broadly, the earlier properties here are cut roofs and anything from the 1970s onward is likely trussed. A photograph looking up inside the loft settles it without a visit.

Coverings and pitch

Concrete interlocking tiles dominate, on pitches typically between 30 and 35 degrees, with some clay on the older properties.

Interlocking tiles are profiled and need a deep flashing kit rather than the flat kit used on slate. A flat kit leaves open voids under the tile channels where it crosses them, and water gets under within a season. It is the most common installation fault we find on other people’s work, it is invisible once the job is finished, and it is exactly where a cheap quotation economises.

Ask any quoting installer which kit is specified for your covering by name and part number. A quotation that cannot answer has not been written from a survey.

Concrete tiles of this age are generally robust and lift cleanly, which makes the work quicker than on a fragile clay roof. Some will be at the end of their life and a proportion will break regardless of care, so a small allowance for replacements is sensible. Where an exact match cannot be found, sound tiles are taken from a hidden slope and the new ones go there.

Where the daylight work is

Rear extensions, mostly. A great many properties here have gained a kitchen or garden room across the back, and flat roof rooflights or a lantern over it is the standard job.

On a modest extension, two or three flat units in a row light a long room more evenly than one large one, cost less, and sit lower from outside. On a larger extension with a flat ceiling and normal head height, a lantern gives volume the room does not otherwise have and collects light from more than one direction, so it stays bright as the sun moves round.

The kerb is what decides whether either lasts: at least 150mm of upstand, the deck falling away from it, and rigid insulation on the outer face.

Orientation and overheating

Worth deciding deliberately rather than defaulting to whichever slope faces the garden.

South gets the most sun through the middle of the day and needs solar control glass as standard. West is frequently worse in practice, because low afternoon sun arrives when the building has already been warming for hours and internal blinds struggle most with low angle light. East gives shorter, cooler morning gain, which suits a kitchen and is difficult over a bedroom. North has no direct sun at all, gives even glare free light all day, and should be specified for thermal performance alone, because solar control there would only make a good room slightly darker.

The second half of the answer is an opening at the highest point of the room so accumulated heat can leave. On a motorised unit with a rain sensor, night purge happens without anybody thinking about it.

Permissions and access

Most Weeley properties are permitted development: a rooflight is permitted provided it projects no more than 150mm beyond the plane of the roof and does not sit above the highest part of it, with additional restrictions on side elevations facing a boundary. Individually listed buildings need consent regardless of slope, and flats have no permitted development rights at all.

Access is generally easy, with off street parking on most roads and space to stand a tower at the rear. Single storey extension work rarely needs scaffold, which keeps the cost noticeably below the older towns.

Obsolete sizes

Normal for anything of that age and entirely solvable. Adapt the opening to the nearest current size, usually within 40mm or 60mm, packing out or trimming back then making good the reveal. Invisible when finished and it leaves a standard size for the next thirty years.

Alternatively find another manufacturer at the old dimension, which suits an opening that is awkward to alter, or reframe entirely where the timber needs replacing anyway.

What nobody should do is force a unit into an opening it does not fit and pack the difference. It survives about a year before the packing settles and the frame goes out of square, and where a quotation is noticeably cheaper than the others this is sometimes why.

The free glass upgrade

A unit fitted twenty five years ago has no low emissivity coating, no argon, an aluminium spacer and no solar control. The replacement has all four as standard, so the room will be warmer in winter, cooler in summer and quieter in rain without paying extra for any of it.

Where the window faces south or west, adding solar control glass at this point costs a modest premium because the labour and access are already being paid for. Coming back for the glass alone later costs nearly as much as the whole replacement.

Doing several together

Access is a fixed cost shared across everything done on the same visit, so two units replaced together cost meaningfully less than two replaced a year apart. Units fitted at the same time fail at about the same time, so if two of three have misted the third is not far behind and it is worth asking what it costs now.

Guarantee

Ten years on our workmanship alongside the manufacturer’s warranty on the product. Most rooflight problems are installation problems, which is why the first matters more, and where a unit fails under the manufacturer’s warranty on a job we did, we handle that claim ourselves.