A roof in the Five Valleys can be older than anyone who has ever owned the house beneath it. Stone slates hang on oak pegs, the timbers were cut by hand, and the joints are often lime rather than cement. Surveying a roof like that is a different job from checking a modern tiled house. The aim is not only to find faults. It is to record what is original, what was replaced along the way, and what can be kept, so that any repair leaves as much of the old roof in place as possible.
This guide is about the survey itself: how we get a view of the roof, what we look for in the stone, the pegs, the mortar and the frame, and how the findings are written up. It covers protected and stone roofs only. For dating any roof, see our answer on estimating roof age. The wider service sits on our roof inspections and surveys page.
Why a stone roof is surveyed differently
A concrete tile is one of thousands cut to the same size. A stone slate is one of a kind, and a stone roof is graded, the longest slates along the eaves and the shortest under the ridge. Each slate has a place in the pattern, so a survey has to read the roof as a whole before it judges any single piece.
Weight changes how we work. Cotswold District Council's 2000 guidance gives roughly 1,000 kg across every 10 m² of stone slate, and the timbers underneath were sized to carry that. We use ladders and roof ladders to spread our own load, and we avoid stepping on slates that look sound but may be cracked beneath the face. On an old roof a careless boot can do more damage than a season of weather.
The three questions
For a protected roof the survey answers three things. What state is the covering in, slate by slate where that matters? What is happening in the structure below? And what is the smallest intervention that will make the roof sound? The last one shapes the whole report. A line that says "replace the roof" is of little use to a planning officer. A line that names the slopes needing re-laying, the slates that can be reused and the timbers needing repair is something the council can actually weigh.
Perished slates, seen from outside and from the loft
Stone does not fail like clay. A perishing slate splits into thin layers along its bed and the face flakes off. That same guidance records about 50% of slates as commonly perished when an old stone roof is stripped, which tells you why a survey from outside can only ever estimate, and why the report states its limits.
From the ground and the ladder
Binoculars and a long lens show slipped and missing slates, sagging courses, wavy tail lines, patches of newer stone that does not match, and moss thick enough to hold water. At the eaves we study the doubled bottom course, the first place where a failing slate lets rain reach the wall head. Up close we check for cracks, flaking faces, chipped corners and slates that have rotated out of line.
The underside tells more
Inside the loft, torch and camera in hand, we check for daylight, for staining down rafters and battens, for rot, and for the state of the pegs. A slate that seems fine from outside can hang on a rotted peg. Seeing its back, the peg hole and the batten beneath is the only way to judge how much of the covering is truly reusable, and you receive photographs of your own roof's underside, not a general description.
Many old roofs also have torching, a lime mortar pushed up between slates and rafters from inside to stop wind blowing through. It sheds dust and fragments as it ages, and its condition says something about the roof's history, so we record it.
Pegs, nails and the signs of earlier patching
Each slate rests on its batten by an oak peg driven through a hole at its top edge, so pegs are one of the first things we examine. Oak rots, splits and wears through the hole, and a slate whose peg has failed creeps down its course. One creeping slate opens a gap above it. A row of them shows from the lane as a ragged tail line. In the loft a dropped peg can sometimes be found lying on the batten.
Nails, clips and sealant
Plenty of old roofs have been patched by someone chasing a leak with nails, metal clips or sealant. We note each one. A nailed stone slate can crack along the nail line, and sealant trapped between slates can keep water against the stone. Neither is a repair a conservation officer wants to see on a roof that should stay reversible, so the record matters. Roofing felt pushed beneath slipped slates is another giveaway: it shows where an earlier hand tried to stop water and failed.
Following a failure to its cause
A patch of slope where many slates have slipped often points past the slates. A batten may have rotted, or a rafter may have deflected under load. We trace the line of the failure into the loft to see whether the cause is the covering, the fixing or the timber. Treating the symptom alone, by replacing slipped slates and leaving a rotted batten, is how a repair gets repeated two winters later.
Our seasonal inspection guide explains how routine checks catch slipping early between full surveys.
Lime, ridge stones and chimney flaunching
The edges of a stone roof are where survey time pays back. Ridge stones are bedded in mortar, and on old roofs that mortar is lime. Lime is softer and more breathable than cement. Where someone has repaired it with cement, the harder mix can hold moisture against the stone and crack it. We check the pointing along the ridge, open joints between ridge stones, and the junctions with chimneys and gables.
Under BS 5534:2014, ridge and hip pieces on new work are fixed mechanically too, with mortar no longer relied on alone. On a listed roof, any change to the way a ridge is fixed is something to raise with the conservation officer, because it can alter the profile and the bedding.
Valleys and verges
The traditional valley is swept in stone, with specially cut slates turning the corner. We check whether a valley is still original stone or has been replaced by lead at some point, since that decides how it should be repaired. Along a verge (the roof edge at a gable end) we look at the pointing and the slate undercloak beneath the edge.
Chimneys and abutments
Where roof meets chimney we look at the lead flashing and at any mortar fillet that stands in for it. Flaunching, the mortar cap that sheds water from around the pot, is often the first thing to wear. On bigger buildings, a method such as the one in our thermal roof survey guide can show damp that a hands-on look misses, though it supports the close inspection and never replaces it.
Timbers, movement and the load of stone
A heavy roof depends on its frame. Oak rafters, purlins, wall plates and tie beams are often original. We study rafter feet where they meet the wall plate, because water from a failed eaves collects there. We check purlins for sag, joints for movement, and timber for softness, rot, beetle damage and old repairs, including rafters that have been doubled up to shore up weakness.
Settled or still moving
Old buildings move. Walls bulge, rafters spread, ridge lines dip. A slightly wavy ridge is often part of a roof's character and not a fault. We look instead for recent movement: fresh cracks in masonry, rafters that have visibly shifted, slates that have dropped within a season. Those point to a cause that has not stopped.
When the covering would change
If a repair would change the material, weight matters. According to the Planning Portal, a replacement covering that is 15 per cent heavier or more than the one it replaces needs Building Regulations approval, and a structural check is advised. Stone is already heavy, so a like-for-like repair seldom raises it. Putting stone onto a roof built for something lighter can. On a listed building, changing the material would also involve listed building consent, and English Heritage policy, as the district council's guide repeats it, rejects artificial stone as a stand-in on historic buildings.
We also note any insulation, boarding or membrane added over the years. Extra layers add load and can hide the timbers, so we say what we could not see.
Listed status, conservation areas and the report itself
Listed status applies to the whole building at every grade, says Stroud District Council. Alterations that would change its special character need authorisation under the 1990 Listed Buildings Act. Whether a given repair counts is for the conservation team to decide, not us, so we advise asking them first. Garden walls and outbuildings may be curtilage structures; the conservation department can confirm their status.
The district has 41 conservation areas, with Article 4 Directions covering five of them. Nothing the council has published confirms whether roofs fall under those directions, so ask the planning team before work is planned. The Cotswolds National Landscape covers over half of the district, and it restricts additions such as dormers but not like-for-like repair.
What a protected-roof report holds
Ours is written so a planning officer can read it. It records the roof slope by slope, with photographs of each, then lists the coverings, the ridge, hip and valley details, flashings, eaves, verges and visible timbers. It separates what is sound, what is worn but repairable and what has failed, and it states how much original material can stay and which repair route keeps most of it.
In our written quote, scaffold, stripping, stone, labour, waste and making good each carry a figure of their own, which lets you weigh the cost before applying for any consent.
Scraping, patching or re-laying: where a survey usually lands
The council's guidance makes a point worth repeating: scraping a stone roof clean each year can double its life, and with regular care a Cotswold roof may stand for a century or more. A survey often ends in a modest list of jobs rather than a new roof.
Three usual outcomes
Some roofs need small repairs: a few perished slates replaced, pegs renewed, a ridge repointed in lime, a flashing relined. Others need a slope re-laid, with the slates stripped, sorted by length and replaced in their own courses, with fresh stone mixed into the courses wherever old slates have perished. A few need the whole roof lifted. Our guides to re-laying a Cotswold stone roof and to reclaimed or new stone slates cover those jobs in depth.
Figures worth knowing
The Checkatrade slate cost guide (body text dated September 2026) gives stone slate at about £160 to £210 per m², varying with source, new or reclaimed stone, and location. It is a national range with nothing specific to the Cotswolds. MyBuilder's 2026 inspection guide gives a typical £150 to £500 for a survey nationally, with thermal surveys at £300 to £500. Your own price follows our visit, in writing, with VAT shown.
Our work carries a 10-year workmanship guarantee in writing. Tell us the address, whether the building is listed and roughly how old the roof is, and we can plan access before we arrive.