Rooflight and skylight installation in Old Heath

The older terraces and cottages

Steep pitches, small plan depths, and coverings that are a mixture of natural slate and plain clay tile depending on when each row was built and whether it has been reroofed since.

Plain clay tiles are the covering we approach most carefully in this trade. They are small, they are laid in double lap, and old ones are brittle. Lifting them to form an opening is slow work and a proportion will break regardless of how carefully it is done. Sourcing matching replacements for a weathered handmade tile is a real task, and the usual answer is to take sound tiles from a rear or hidden slope and put the new ones there.

Underlay is the other question. A roof of this age that has not been stripped and reroofed may have none, and modern rooflight weathering assumes a membrane to lap into. Where there is not one, the detailing is built around the opening instead. It is entirely normal and it needs to be priced rather than discovered.

Rafters in these roofs are often smaller in section than modern ones and irregularly spaced. Where a wider skylight is wanted, trimming is likely, and on a small terrace roof that is a genuine structural consideration rather than a formality.

Condensation, which is not a leak

More relevant in the older Old Heath housing than almost anywhere, and the single most common thing we are called out to that turns out not to be a fault.

An older cottage with modern heating, modern airtightness measures and no ventilation strategy produces a lot of moist air with nowhere to go. It condenses on the coldest surface in the room, which is very often the glass of a rooflight or the plaster reveal around it. Water appears, it runs, and it looks exactly like a leak.

Telling them apart is straightforward once you know what to look for. Condensation appears on cold mornings, is worst in winter, forms on the inside face of the glass or evenly around the reveal, and is unrelated to whether it has rained. A leak follows rain, appears at one point rather than evenly, and often leaves a mark that persists after it dries.

Where it is condensation on the reveal specifically, that usually does point at an installation problem: a missing insulation collar. The collar closes the gap between frame and structure, and without it the reveal is cold enough to condense. It is a separate order line, it is commonly omitted from cheap quotations, and its absence shows up months later when nobody connects the two.

The post war housing

Different roofs entirely. Concrete interlocking tiles, pitches around 30 to 35 degrees, and increasingly trussed rafter structures on the later blocks.

Profiled tiles need a deep flashing kit rather than the flat kit used on slate, and trussed roofs limit opening width to the truss spacing unless a designed trimmer is installed. Both are routine, both change the price, and both are the sort of thing an honest quotation says out loud.

These houses take a straightforward roof window very well and a lot of what we do here is exactly that: one or two units in a rear slope to bring daylight into a landing or a converted loft.

Replacement work

A substantial share of what we do in Old Heath is replacing units that have failed rather than fitting new ones. Sealed units on rooflights last fifteen to twenty five years, and a great many went into this part of Colchester in the 1990s.

A like for like swap into a sound opening is the cheapest job in this trade. The size code is frequently obsolete, which is normal and solvable, usually by adapting the opening slightly to the nearest current size and making good the reveal. What we will not do is force a unit into an opening it does not fit and pack the difference, which survives about a year before the frame goes out of square.

Access and parking

The main practical constraint here. The older terraces have no off street parking, narrow frontages directly onto the pavement, and in places no side access to the rear at all. Where scaffold has to go up at the front over a pavement, a licence from the highway authority is needed and it takes time to arrange.

Where there is no side access, materials and scaffold sometimes have to come through the house, which is entirely normal and needs planning rather than improvising. We would rather establish it at survey than turn up and find out.

The post war roads are much easier, with driveways and space to stand a tower.

Getting a price

A photograph of the roof from outside, one of the front of the property showing the access, and one of any existing unit’s data plate. Between those we can usually tell you what the job is and roughly what it costs.

Sun tunnels in the terraces

The older Old Heath terraces have narrow plans and internal bathrooms and hallways with no external wall and no available slope. That is exactly the situation a sun tunnel solves and it is a large part of what we fit around here.

A rigid mirrored tube runs from a small dome in the roof down to a diffuser in the ceiling and brings genuine daylight into a room that has never had any. It is the cheapest daylight in this trade by a distance, and the roof component is small and low enough that on a rear slope it is effectively invisible from the street, which matters near the older core.

It is not a rooflight and we will not pretend otherwise. There is no view, no ventilation and no sense of sky. What there is, on a dull afternoon, is enough soft light to walk into a windowless bathroom without reaching for the switch, and for the money that is a good proposition.

Size it properly. Output goes with area rather than width, so 350mm passes roughly twice the light of 250mm. And insulate the tube where it crosses the cold loft, because a metal tube through unheated space collects condensation and the water arrives at the diffuser looking exactly like a leak.

Extensions toward the Hythe side

The post war housing on the eastern side of Old Heath has gained a lot of rear extensions, and flat roof skylights over them are steady work.

The first thing we look at is the kerb, because on an older or self built extension there frequently is not one. A rooflight bedded straight onto a flat deck sits in whatever water the roof holds, and every flat roof holds some. A kerb of at least 150mm, insulated on its outer face, with the deck falling away from it, is the difference between a twenty five year installation and a problem in three winters.

The insulated outer face is the detail nobody mentions. A 1200 by 1800 rooflight has six metres of perimeter, and an uninsulated timber kerb punching through the roof insulation presents nearly a square metre of poor performing envelope. It is a sheet of rigid insulation and an hour, it is invisible once the covering is dressed over it, and that is exactly why it gets skipped.

What it costs

The variables here are access and what is found. A rear slope reachable from a tower on one of the post war roads is at the cheap end. A front elevation on a terrace with no off street parking, needing a highway licence for scaffold, is at the other, and the licence is a real line rather than a rounding error.

On any older property we name a contingency for decayed timber rather than pretending it cannot happen. On a unit that has been failing quietly for years it is a real possibility.