Skylights, roof windows & rooflights in Macclesfield

A roof window is a hole cut in a working roof, so all of the risk sits in the detailing round it rather than in the unit. Fitted properly with the correct flashing kit for the covering, it is as watertight as the roof it sits in. Fitted with the wrong kit, or with lead dressed over the top because the right kit was not ordered, it leaks — usually at the top corners, usually within two winters.

Most 'my skylight is leaking' calls turn out not to be the glazing at all. It is the flashing apron below it, the soakers at the sides, a failed seal on a twenty-year-old unit whose gaskets have simply gone hard, or condensation running off cold glass and pooling on the sill — which looks exactly like a leak and is fixed with ventilation rather than lead.

Replacement is often much easier than people expect. The major manufacturers have kept their frame sizes stable for decades, so a tired unit can frequently be swapped into the existing opening with a new flashing kit and no structural work at all. Whether that is true of yours is a five-minute check of the size plate on the sash.

Cutting a new opening is a different job, because it usually means trimming a rafter, and that is structural. It needs a proper trimmed opening and, depending on the span and the covering, it may need Building Control involvement. On a flat roof the equivalents are lanterns and flat-glass rooflights, where the upstand height and the fall around it decide whether it works.