Conservation Rooflight Installation
Slim cast frames set flush, for stone slate, listed and conservation roofs.
the Cotswolds
Rooflight and skylight installation in Andoversford, surveyed first, and fitted once.
Andoversford, and the roofs around it: small village on the wolds, exposure. Everything below is what that means once the covering comes off.
- Covered from Gloucester
- 15 years on Gloucestershire roofs
- 10 year workmanship guarantee
- From Gloucester by road
- 15 to 30 milesApproximate, and inside the 30 mile radius
- Dominant roof stock
- Cotswold stone slate in diminishing coursesWhat the covering is decides the detail
- The usual constraint
- Conservation consent and matching the stoneSettled at survey, before anything is ordered
- Local character
- small village on the wolds, exposureRecorded for Andoversford specifically
In Andoversford
Rooflights we fit around Andoversford
VELUX Window Installation
VELUX fitted alongside Fakro, Keylite and Roto, chosen to suit the roof.
Electric and Opening Rooflights
Actuated openers, rain sensors and controls, wired and commissioned.
Energy Efficient Rooflights
Specified on U-value and g-value for the way the roof actually faces.
Replacing a Failed or Misted Rooflight
Misted and tired units taken out, and the opening made good underneath.
Walk-On Rooflight Installation
Structural glass rated to stand on, over rooms below a terrace.
The local detail
Fifteen things worth knowing about Andoversford roofs, worth reading before the survey.
Andoversford is a working village on the A40 rather than a showpiece, and that makes it one of the more straightforward wolds addresses to put a rooflight into. It grew around a road junction and later a railway junction, it expanded through the twentieth century, and a good proportion of its housing is post-war and later, in brick or reconstituted stone with concrete interlocking tile over it. There is an older stone core and there are farm buildings around it where the full Cotswold method applies. But for a large share of the village, the honest answer to an enquiry is that the roof is ordinary, the work is a day outside and a day inside, and no planning application is needed at all. Severn Skylights Gloucester reaches Andoversford easily from Gloucester, and the constraint that actually matters here is not consent. It is the weather.
The most straightforward wolds address in this part of the county
Every other Cotswold page on this site opens with a constraint. This one opens with the opposite, because it is true and because homeowners here regularly assume a Cotswold postcode implies a heritage problem they do not have.
Outside the historic core, a great deal of Andoversford housing is undesignated, roofed in a manufactured covering with a matching flashing kit available off the shelf, built with a roof structure that is either a straightforward cut roof or a trussed one with known dimensions. That means no reclaimed stone to source, no torching to negotiate, no conservation officer to consult, and a lead time set by the unit rather than by a reclamation yard. The Building Control notification still applies, and it is handled as part of the job.
A village built around a road junction rather than a market place
The shape of Andoversford explains its housing. It sits where the A40 meets the roads running north and south across the wolds, and it developed as a place people passed through and stopped at rather than as a market town with burgage plots running back from a square.
So the plan form is linear and loose rather than tight and medieval. Houses have space around them, driveways, and in many cases a route to the rear that a scaffold lorry can actually use. Compared with Chipping Campden or Bibury, where tube and boards frequently have to be carried through the house, that difference alone is a meaningful part of the price. Where Severn travels and what each part of the county involves is on the areas pages.
The former railway junction, and the housing that came after it
Two lines met at Andoversford and the village had a station and a junction serving them until the closures of the 1960s. The railway is long gone and the earthworks are mostly absorbed into fields, but the period of building it prompted is still standing.
That gives a spread of stock across several decades: railway era cottages, interwar and post-war housing, later twentieth century infill and modern development. Each of those brings a different roof. Small format slate or clay tile on the oldest, concrete interlocking tile from the 1950s onwards, trussed construction from roughly the 1960s, and attic trusses on the newest houses where the loft was designed as a room from the start. Identifying which one is standing over you is the first survey question, and it is answered from inside the void rather than from the drive.
The covering
Cotswold stone slate laid in diminishing courses on torched battens, the covering that decides the whole detail.
Cotswold stone slate in diminishing courses, which is what the survey is looking at before it looks at the glass.
Concrete interlocking tile, and the easiest opening Severn forms
A concrete interlocking tile roof at 25 to 35 degrees is the most predictable covering in the county to put a unit into, and it is worth setting out why rather than just asserting it.
The tiles are a repeating module, so the gauge is uniform and a course boundary is in a known place every 300 to 350mm up the slope. They unclip and lift without breaking, so the covering is stripped back and stacked for re-use with almost no loss. There is a manufactured flashing kit pressed for the profile, so the apron, side flashings and head flashing arrive matched rather than being formed on the scaffold. And replacements are available new rather than needing to be hunted for. What that adds up to is an opening formed, a unit set, flashings dressed and the covering re-laid within a single day outside, with the reveal, insulation and plaster following on a second day.
Trussed roofs on the newer Andoversford estates
Where the house is 1960s or later the roof is very likely trussed: factory made triangulated frames at 600mm centres, joined with punched metal nail plates, designed to work as one structure. The rule is simple and it is not negotiable. The webs and the chords stay whole.
Between two trusses at 600 centres there is around 550 to 570mm of clear width, and the manufacturers make units precisely for that gap, commonly 550mm wide by 780, 980 or 1180mm long. A unit in that range needs a head trimmer and a cill trimmer between the two trusses and nothing more, and two of them in adjacent bays give a good spread of light on a rear slope. Anything wider means carrying part of a truss on a designed member spanning to the trusses either side, which is a structural engineer’s calculation, a deeper timber or a small steel, and a Building Control approval before the covering comes off. That is often the right thing to do for a loft room, and it is a different job with a different programme. The detail is on rooflights in a trussed roof and what cannot be cut.
Conservation here is not a formality. It is the reason the stock still looks like this.
The older stone core, where the Cotswold method does still apply
The older part of the village and the farmsteads around it are limestone with stone slate over them, and there the work is a different trade entirely.
The slates are graded and laid in diminishing courses, largest and thickest at the eaves and reducing continuously to the ridge, on riven battens and frequently torched underneath with lime mortar in place of any membrane. An opening is formed by stripping the courses back up the slope, setting the frame, and re-laying downwards to the original gauge, with reclaimed stone matched for thickness and weathering colour where slates break. The unit is a slim framed conservation type rather than a standard roof window, because a standard frame and kit cannot bed onto a 25mm irregular slate. Those two subjects are on rooflights in natural slate roofs and conservation rooflight installation.
Exposure on the high wold, and what wind does to a specification
This is the Andoversford constraint. The village sits high and open, the wolds around it carry very little shelter, and the prevailing wind comes across them from the south west with nothing much in the way.
Wind acts on a roof as uplift rather than as pressure, and the worst of it is at the verges, the ridge and the eaves, which is where suction peaks. An opening in the middle of a slope introduces two new vertical edges and a new horizontal one into a covering that was designed as a continuous surface, and those edges become local pressure concentrations. The response is mechanical rather than clever: every cut tile or slate at the perimeter of the opening is mechanically fixed rather than relying on its own weight and its interlock, clips are used where a nail cannot be reached, and the fixing specification around the opening goes beyond what the same roof needs in its uninterrupted field.
On an exposed wold roof, every cut piece around the opening is mechanically fixed, because an interlock alone is not a fixing.
Driving rain from the south west, and headlap above the minimum
The second consequence of exposure is water travelling upward and sideways rather than simply downward. Wind driven rain climbs a lap that would be perfectly adequate in a sheltered valley.
So the laps get increased. On a slate covering, a headlap of 100mm is a general figure for a moderate pitch in a sheltered position, and on an exposed wold slope a roof will often be found running 115 or 125mm instead. On an interlocking tile the minimum lap for the profile goes up rather than being taken at the manufacturer’s floor. Around a rooflight this is a quantity rather than an opinion: the interleaved soakers down each side lap each other by the same figure the covering does, so an increased headlap means deeper soakers and more lead per course, worked out from the measured lap rather than assumed. Side flashings are taken wider for the same reason.
Solar gain on a south facing wold roof, and the coating that earns its money
An open site cuts both ways. What it costs in wind it gives back in daylight, because there is nothing shading these roofs, and a south or west facing slope at Andoversford takes direct sun for as much of the day as anywhere in Gloucestershire.
That is excellent for a north facing room and a problem for a loft bedroom, where the glass is overhead and the sun is on it at the hottest part of the afternoon. A solar control coating on the outer pane brings the g-value down from around 0.5 to roughly 0.25 to 0.3, which on a west facing conversion is the difference between a usable summer bedroom and an unusable one. It costs very little at the point of order and cannot be added afterwards. An external awning blind, fitted above the glass rather than behind it, does more again, because it stops the heat before it reaches the pane. The numbers are on energy efficient rooflights.
the Cotswolds
Torched battens are the reason a stone slate roof is opened carefully and closed properly.
Farm buildings and barn conversions around Andoversford
The land around the village is arable wold with farmsteads on it, and stone barns converted to houses are a recurring enquiry. They are also the one Andoversford building type where the consent position is more complicated rather than less.
Three things stack up. A barn within the curtilage of a listed farmhouse, present before July 1948 and in the same ownership at the date of listing, may itself be listed by association without appearing under its own name anywhere. A conversion carried out under the agricultural to residential prior approval route has no permitted development rights for roof alterations at all, so consent is needed regardless of size. And a conversion granted through full planning permission very often carries a condition restricting the number, size and type of rooflights, which sits on top of everything else. All three are checked from the planning history for the address before any unit is specified, and the general position is on conservation areas and listed buildings in Gloucestershire.
Consent for an ordinary Andoversford house, and the limit worth knowing
For an undesignated house in the village, a rooflight is permitted development and the application is simply not needed. The limits are still real and there are two of them worth knowing.
The alteration must not project more than 150mm beyond the plane of the existing roof slope, and it must not be higher than the highest part of the existing roof. The 150mm figure is why an in-plane roof window is almost always inside the limit and why a bulky kerb mounted unit on a pitched slope may not be. A side facing unit in a room in the roof needs obscure glazing and must be non-opening unless the opening part is more than 1.7 metres above the floor. Flats and maisonettes have no permitted development rights for roof alterations at all. Where a sale is anywhere in prospect, a lawful development certificate is a modest fee for a document a solicitor will accept. Full detail on permitted development limits for rooflights.
The covering
Cotswold stone slate laid in diminishing courses on torched battens, the covering that decides the whole detail.
Cotswold stone slate in diminishing courses, which is what the survey is looking at before it looks at the glass.
Frost, wind and a winter date on an exposed site
A job here in January is planned differently from the same job in a sheltered valley, and it is better to say so than to move a date at short notice.
Two practical limits. Lead is dressed cold, and a bossed detail formed in a hard frost with numb hands is not the same piece of work as one formed at ten degrees, so genuinely freezing mornings shift the start of outside work rather than cancelling it. And wind speed governs whether anybody is handling a large sheet of glass on a scaffold at all. A made-to-size flat roof unit or a lantern pane behaves like a sail, and there is a wind speed above which lifting it is not sensible. The rule that the roof is never left open overnight applies through all of it: an opening is not started unless it can be closed and made watertight the same day, and if the forecast turns during the morning, work stops at a point where the covering is whole.
Getting scaffold to an Andoversford address
Access here is usually good and occasionally awkward, and the difference is worth establishing on the survey rather than on the morning.
Most of the village has driveways, verge or a side route to the rear that a lorry can use, and the A40 gives an easy approach. What causes trouble is a farm track in wet weather, a shared access with a passing place that a scaffold lorry cannot use, and any position where the scaffold has to stand on the highway and a licence is needed. Where the roof faces the A40 itself, deliveries and lifts get timed away from the busiest hours. None of it is difficult, and it is all cheaper than in the valley villages, which is one of the reasons an Andoversford quotation looks different from a Bibury one for the same unit.
Conservation here is not a formality. It is the reason the stock still looks like this.
What a loft room here needs, and the rules behind it
Where the space under the new opening is a habitable room in the roof rather than a loft void, several requirements engage at once and they are handled as part of the job.
- Structure. Trimming designed before anything is cut, with a calculation where the opening crosses more than one bay or involves a truss.
- Fire. Where the unit is the escape opening, a clear openable area of at least 0.33 square metres, minimum 450mm each way, bottom of the opening 800 to 1100mm above the floor.
- Thermal. The unit inside the current limiting standard, with insulation continuous around the reveal and the vapour control layer taped to the frame.
- Ventilation. Purge ventilation of at least one twentieth of the floor area, plus background ventilation from the vent flap in the head of the unit.
- Glazing. Toughened outer and laminated inner wherever there is habitable space, a stair or a bath below.
The notification goes in, the inspections are booked, and the completion certificate comes back in the homeowner’s name. It is the document a buyer’s solicitor asks for, and finding it missing at the point of sale is a worse problem than dealing with it now.
On Andoversford roofs Conservation consent and matching the stone.
From an Andoversford enquiry to a date in the diary
Email photographs of the roof from outside and the room from inside, the covering if you know it, roughly where the daylight is wanted, and the address, to info@severnskylightsgloucester.co.uk. On most Andoversford addresses the indicative range comes back quickly, because there is no designation research holding it up.
A survey follows, taking the covering, the pitch off a digital level, the rafter or truss centres, the purlin positions, the insulation and the ventilation path, plus the access route and the exposure of the slope. The fixed price after that is itemised: unit, labour, scaffold, flashing kit, Building Control, and internal finish. It holds unless the scope changes at your request. The workmanship carries a ten year guarantee, neighbouring Northleach and Cheltenham have their own pages, and the costs page sets out how the two figures work.
Also covered: the Cotswolds