Anyone who owns an old building in Bath ends up with the same problem sooner or later: the roof is doing something odd, and nobody can say what is original, what was patched in the twentieth century and what has to be kept. A historic roof survey exists to answer that before a ladder goes up for repairs. It is a careful look at the covering, the lead, the stonework around it and the timbers beneath, with the findings written down and photographed. The record then does several jobs. It tells the owner what is wrong, it gives the conservation officer something concrete to read, and it lets a roofer price like-for-like repairs instead of a generic re-roof. Every street in Bath lies inside the World Heritage Site boundary, roughly half the city is conservation area and around 5,000 buildings are listed, so a good many roofs here fall into this category. Such a survey follows a careful method, and what comes out of it is a record you can plan repairs around.
What sets a historic roof apart
A roof built in the eighteenth or nineteenth century was put together by hand, with materials chosen for the site. Slates were graded by size and hung in diminishing courses, small at the ridge and larger towards the eaves. Stone tiles were selected and sorted by thickness. Valleys and parapet gutters were lined with cast or rolled lead and shaped by the building they served. Nothing was standardised the way a modern roof is, so no catalogue can tell you what you have.
That matters for two reasons. First, repairs have to copy the original's material, size and detailing, or the roof will look wrong and may perform badly. A modern slate pushed into an old roof can stand proud of the courses around it and admit water. Second, older buildings have often been altered. A roof may now carry a patchwork: Welsh slate on the front slope, a clay pantile section at the back, cement mortar on the chimney and a flat felt roof where a dormer was removed. Comments by the Bath Preservation Trust on 33 St James's Square, listed Grade I, mention Welsh natural slate across the pitch and clay pantiles on the rear slope. That kind of mixture is normal on a building that has been looked after for generations, and a survey needs to record it rather than assume uniformity.
Older roofs also tend to hide their problems. A split in a lead valley, a slipped slate behind a parapet or a rotted wall plate under a gutter will not show from the pavement. The only way to find them is a hands-on or camera-led inspection that looks at the details.
Listing, conservation area and who to ask first
The survey starts at a desk. Before anyone goes on the roof, we find out the building's status: listed or not, and in or out of the conservation area. The list entry held by Historic England states the building's grade and summarises what it is. It can be found by address, and sometimes it mentions the roof covering and its form.
Status shapes what happens after the survey. Where a building has a listing, decisions rest with B&NES Council, which wants a phone call before anything begins. Two applications exist and they are not interchangeable. Skipping the listed one is an offence, whatever the builder says. A survey changes nothing about the building, so it needs no consent. The repairs it recommends might.
For an unlisted building in the Bath conservation area, the position is different but still worth checking. Roughly half of Bath sits in the conservation area, and certain streets also carry Article 4 directions, under which certain permitted development rights no longer apply. The examples the council gives do not include roofs, so no blanket rule applies; the answer turns on the street and the work. Our survey notes the status and lists the points to raise with the council. You can find the council's guidance on listed buildings at B&NES, and its conservation team is the right place to ask about a specific proposal.
Whether consent is needed is for the council to say. What we offer is a clear record and a note of the repairs most likely to prompt questions.
Recording the covering
The covering is the first thing that is recorded in detail. For slate that means the type, the sizes, the courses and the condition. The survey records what is actually there rather than assuming a type. We note whether the slates are laid in diminishing courses, whether they are fixed with nails or pegs, and where patching has happened. On one Lambridge Place terrace the Bath Preservation Trust preferred genuine Welsh slate to the artificial substitute, which hints at what the planning side values: the correct material, rather than any covering that keeps rain out.
Nails are a particular concern. Iron or poorly galvanised nails on a slate roof corrode long before the slate fails, and then slates slip. Stirling City Heritage Trust calls this nail sickness. A survey looks for the signs: slates sitting low in their courses, rust staining on the surface and a trail of slipped slates down one slope. Where that pattern is found, the report says so, because it points to a re-fixing job rather than a series of spot repairs. Copper, aluminium or silicon-bronze nails are the choice that lasts, according to the British Standard as summarised by Northern Ireland's Historic Environment Division.
For stone tiles and clay tiles the survey notes tile size, thickness, fixing and the mortar or lime bedding at the ridge and verge. Cotswold stone tiles still appear on some older buildings in the villages of Wellow and Freshford, according to the council's conservation appraisals for them. They are rare, and reusing them is preferable. The report states which tiles are sound, which are failing and whether any can be salvaged.
Lead, stonework and chimneys
On older Bath buildings the lead is often where the roof fails first. The valleys, the gutters behind parapets and the flashings round chimneys all depend on sheets of lead laid in lengths with joints and drips. Lead is worked by temperature, swelling in warmth and shrinking in cold, and after many years it cracks at the folds. The survey checks each lead run for splits, cracks at drips, lifting at the edges and signs of patching with the wrong material.
The parapet gutter, lined with lead, runs behind the stone upstand at the front or side of a building. A valley, where two slopes meet, is a close relation. Each drains a big area, and you will not spot either from the pavement. Where they cannot be reached without risk, we use a pole camera or a drone so nobody has to kneel on fragile lead. The Bath Preservation Trust supported the re-leading of the central and side valley gutters on the Grade I house at 33 St James's Square, and that is routine work on a well-kept building.
Chimneys come next. The survey looks at pointing, the condition of the flaunching, the sloping mortar collar around the pots, and the stone itself. At 7 Walcot Buildings the Trust wanted repointing in lime mortar, which lets old stone breathe, and noted that cement can worsen stone damage. We record whether past repairs used cement, because lime and cement behave differently and repairs in the wrong one accelerate decay.
Parapets, copings and the stone below the roofline are recorded as well. Water from a failing coping or open joint soaks into the wall and, in time, into the roof timbers.
Timbers and the roof space
The inside of an old roof tells you as much as the outside, and often more. Where the roof space can be entered safely, we look at the rafters, purlins, ceiling joists, wall plates and any trusses. We are checking for dampness, decay, insect damage, old repairs, sagging and daylight where there should be none. In a lime-plastered building the plaster ceiling below is part of the picture too, since staining there shows where water has been getting in.
Timber condition decides whether a roof can be repaired or has to be stripped back. Sound timbers mean the covering may often be repaired or relaid. A wall plate rotted under a leaking gutter is different: the bad section must be cut out and new timber spliced in first. The report records which of these cases applies. It never guesses where it cannot see, and it lists the sections that could not be reached.
Roof spaces suit bats and nesting birds too. Both roosting bats and active nests have legal protection. If we see signs of either, the report says so and the work plan allows for it, with Natural England as the contact for licensing. This is one of the reasons the survey comes before the repair rather than after the first leak.
Insulation and ventilation are noted last. Old roofs were built to breathe, and a well-meant layer of foam or tightly fitted membrane can trap moisture against ancient timber. The survey records what is in the roof space now, because any new insulation has to suit the structure it is going into.
Getting access without harming the roof
Old coverings are fragile, so the survey is planned to avoid walking on them where possible. Slate and stone tiles crack under boots, and lead dents under knees. The lightest method that gives a good view is used first: ground-level photography with a long lens, then a pole camera, then ladders and roof ladders, and a tower or scaffold only if the roof warrants it. Our guide to pole camera inspections explains what that equipment shows and where it stops.
Some access is unavoidable. A parapet gutter cannot be judged from below, and a valley between two slopes needs a closer look. In those places the work is done from a safe position with edge protection where the roof has drops. Should a roof be too delicate to bear any weight, the survey is limited to what can be seen from other positions, and the report states the limits.
Large buildings add another layer. A Georgian terrace converted into flats has several owners and a common roof. The same methods apply, with the extra step of agreeing access with each occupier and the managing agent, as described in our guide to surveying blocks of flats.
Photography is thorough on every historic survey. We photograph your own roof from every position we can reach, and number the pictures so that each can be matched to a plan. If a conservation officer later asks to see the condition of a valley or the type of nail, the picture exists.
The record, and what it leads to
The report that follows is written to be used. It contains a description of the roof by area, a plan or annotated sketch, a photo schedule and a list of defects ranked by urgency. It names the materials found, with sizes where they matter, and it lists those that should be kept, repaired or replaced. A section on consent lists the points to raise with B&NES before any work begins. Where we recommend a repair, we say whether it is like for like, because that determines how the council will see it.
The same record helps in other ways. It supports a listed building consent application with evidence. It gives an insurer a baseline if a claim is made later. It also gives future owners a history of the roof. A conservation architect or structural engineer can use it as a starting point if the roof needs more specialist attention.
The time it takes depends on the building. A modest terrace roof with easy access takes less than a large townhouse with several roofs, a parapet gutter and a roof space reached through a narrow hatch. For a sense of the range, see our guide on how long a roof inspection takes.
After the survey, a fixed price in writing follows for the recommended repairs, with the scope and materials set out item by item. Where repair does the job, repair is the advice. Our roof inspection service sets out the broader approach, and it is wise to share the survey with the conservation officer before work starts, as it shows the repairs are like for like.