Rooflight and skylight installation in Highnam, and the roof it has to sit in.

Four miles west of the river, and the two Highnams a survey finds

The older Highnam is an estate village: Highnam Court and its park, the church beside it, and the cottages and lodges built to serve them. The building character is deliberate and consistent. Steep roofs, prominent gables, decorative bargeboards, tall chimneys and brickwork with contrasting bands. The roofs are cut, not trussed, with rafters, purlins and struts, and they are steep enough that a roof window in them stands well proud of head height inside.

The later Highnam is the housing laid out along and behind the Newent road from the nineteen seventies onwards, and it keeps growing. Detached and semi-detached houses on cul-de-sacs and closes, brick with concrete interlocking tiles, garages either attached or integral, pitches usually between 25 and 35 degrees, and factory-made trussed rafters at 600mm centres holding the whole thing up.

Between the two sit the farmhouses, the converted agricultural buildings and the individual houses along the lanes towards Lassington, Over and Rudford. Those are the ones where the survey takes longest, because the covering, the structure and the designation all have to be established rather than assumed.

The later housing off the Newent road, and the trusses inside it

A trussed rafter roof is a triangulated frame assembled in a factory with punched metal nail plates, and it works as a whole. The webs and the chords carry load in a designed path and they stay whole. Cut a web to make room for a wider window and the truss deflects, and the evidence turns up months later as a line in the ceiling rather than as a noise on the day.

So the opening works with the module. Between two trusses at 600mm centres there is roughly 550 to 570mm of clear width, and the manufacturers make units to suit: 550mm wide by 780, 980 or 1180mm long. One of those needs a head and cill trimmer between the two trusses and nothing else, and it goes in inside a day. Two in adjacent bays give more glass than one wide unit would and light a room more evenly. Anything wider means part of a truss carried on a designed beam spanning to the trusses either side, which is an engineer’s calculation and a Building Control approval before the tiles come off. The full picture is on rooflights in a trussed roof.

Some of the newest houses in the village were built with attic trusses, where the loft was designed from the outset as a room. Those have a clear rectangle down the middle by design, and an opening in one is among the most straightforward jobs available.

Wind off open ground west of the Severn, and the headlap that answers it

Highnam sits on flat open land with the river to the east and fields on the other three sides, and there is very little between the village and the weather coming up the vale. Driving rain arrives from the south west with nothing to slow it, which has a specific effect on a roof opening.

Wind driven rain does not fall onto a roof, it travels across it, and at the sides of a new frame it will be pushed uphill against the direction the covering wants to shed it. The answers are all in the detailing. Side flashings are taken wider than the kit minimum. Head laps are increased above the manufacturer’s stated figure rather than set at it. The underlay is cut as a tongue and dressed up over the head of the frame and into the frame’s own drainage channel at the sides, so anything crossing the covering lands on membrane and runs down outside the timber. That last detail is invisible for the life of the roof and it is the one that decides whether a mark ever shows on a ceiling.

Barns, stables and outbuildings on the Highnam side of the river

The land around the village is farmed, and there are agricultural ranges in stone, brick and corrugated sheet, some still in agricultural use and some converted or being converted. Rooflight enquiries on those come with two conditions attached that a house does not carry.

The first is designation. Listing extends to structures within the curtilage of a listed building that were standing before 1 July 1948 and were in the same ownership when the listing was made, so a barn a hundred metres from a listed house can be listed by association without ever appearing under its own name. That is discovered late far more often than it should be, and the full position is set out on conservation areas and listed buildings in Gloucestershire.

The second is the conversion route. A barn converted through the agricultural to residential prior approval process has no permitted development rights for roof alterations at all, so an application is needed whatever the size of the unit. Conversions granted through full planning permission very often carry conditions capping the number, size and type of rooflights, and those conditions sit on top of everything else. Reading the decision notice before choosing a unit saves a great deal of time.

Bungalows and dormer bungalows around the village

There is a fair amount of single storey and chalet housing in and around Highnam, and a bungalow is an unusually good candidate for daylight from above. Every room has roof over it, so there is no first floor in the way, and a rooflight can be put almost anywhere the structure allows rather than only over a landing.

The structural picture is usually straightforward. A bungalow of this period is either a cut roof with purlins, in which case rafters can be trimmed in the normal way, or a trussed roof, in which case the 600mm module applies exactly as it does in the two storey houses. The ceiling is at the bottom of the roof void rather than following the slope, so a rooflight needs a lightwell: an insulated shaft from the frame down through the loft to the ceiling line, plasterboarded and plastered inside, with the sides splayed so the daylight spreads rather than dropping in a column. A splayed shaft over a hallway or a bathroom is one of the most effective things you can do to a bungalow, and where the run is long and the aperture wanted is small, a sun tunnel does the same job with far less disturbance to the ceiling.

Consent at Highnam, and the authority that is not Gloucester City

Highnam is a parish outside the Gloucester city boundary, so an application for an address in the village does not go to the city council even though the city is four miles away across the river. That sounds like a technicality and it is not: submitting to the wrong authority costs weeks, and the correct one is confirmed against the address before anything is prepared.

Most rooflights in a house in the village go in under permitted development. The limit that catches people is the projection: an alteration to the roof of a house must not project more than 150mm beyond the plane of the existing slope, and it must not be higher than the highest part of the existing roof. An in-plane roof window satisfies that comfortably. A bulky kerb-mounted unit on a pitched slope may not. Side facing windows serving a room in the roof carry an extra condition of obscure glazing and no opening part below 1.7 metres from the floor.

Where a property in the village is listed or sits inside a designated area, the position changes and pre-application advice is worth far more than it costs. The unit that satisfies an officer is usually a slim dark framed conservation rooflight, specified before the application rather than after it.

What a day at a Highnam address looks like

Scaffold or a tower goes up first. Inside, floors and furniture are covered before anything is cut, and the loft hatch is closed and sealed while cutting happens so dust stays in one place. The opening is set out from inside so the reveal lands where the room wants it, then transferred outside by drilling through at the corners.

The covering is stripped back and stacked for re-use, the underlay cut and dressed, the opening formed and trimmed, and the unit set, fixed and flashed. The covering is then re-laid into the flashings. On a straightforward roof window in an accessible slope, that is one day outside, with the insulated reveal, vapour layer and plaster following on a second day. On a steep plain tile roof at the estate end of the village it takes longer, because the disturbed area is larger and the tiles are handled one at a time.

The Building Control notification is submitted as part of the job, the inspections are booked, and the completion certificate comes back in the homeowner’s name. Keep it. It is the document a buyer’s solicitor asks for, and its absence is a much larger problem at the point of sale than dealing with it now.

Two figures, and how a Highnam enquiry starts

Nothing is priced from a postcode. A conservation unit into a steep plain tile roof on an estate cottage and a 550 by 980 window between two trusses on a nineteen nineties detached are not the same job, and one figure covering both would be wrong for both.

What moves it: the covering and how much of it has to come off, whether any structural work is needed, the size wanted against the rafter or truss spacing, how many units and whether one scaffold covers them all, how far material has to be carried from where a lorry can stop, the glass specification, whether the unit is fixed, manual or electric, and how far the internal finish is taken.

Then two figures in this order. An indicative range by email first, based on a photograph of the roof from outside, a photograph of the room from inside, the covering if you know it, a rough size and the address. Then, after a survey, a fixed price itemised so it is clear what is unit, what is labour, what is scaffold and what is Building Control. That figure holds unless the scope changes at your request or something structural is uncovered that was flagged as a risk in the survey notes beforehand. Send photographs to info@severnskylightsgloucester.co.uk. The costs page explains how a range becomes a fixed price, and the written guides go further into individual questions.