Tibshelf is a village with a long working history. It was recorded in Domesday in 1066, and in the nineteenth century coal was discovered, which pushed mining past agriculture as the main industry and brought a local railway system. A place that grows quickly in one era tends to have houses of similar age and construction, and then a ring of later additions. We do not claim to know each street, but we can describe what a loft survey usually looks for in that kind of housing.
In an older house, the roof is often a cut roof with purlins and common rafters. The timbers carry the roof covering and resist the weight of tiles or slate. A roof window set between the rafters is the cleanest fit, as it needs the least cutting, and a window sized to the rafter gap saves trimming. Where a window needs to be wider than the gap, a pair of rafters is cut, and a proper header carries the load around the opening.
In newer houses the roof is often trussed. The webs between rafters limit the position of the opening, and sometimes the window has to move a little to avoid them. A trussed roof also means the loft is less usable as a room, so a roof window there tends to light a landing, a stair or a first-floor room through a short light well.
Extensions have flat roofs more often than not. A flat roof asks for a joisted opening, an upstand built up from insulated timber, and the roof covering dressed over it. Done well, it is as watertight as any pitched slope. Done badly, it leaks within a winter, which is why the build-up is described in the quote.