Bath has around 5,000 listed buildings, and many of them rely on lead to stay dry. It lines the gutters behind the parapets, covers the flat tops of bays and porches, turns the corners at chimneys and runs down the valleys between pitched roofs. When that lead wears out or splits, the owner of a listed house faces a question that an unlisted neighbour does not: how much of the repair is routine and how much needs the council's agreement? This guide explains how leadwork is renewed on a listed building. It covers what like for like means in practice, which details matter most, how the consent question is approached, what the Bath Preservation Trust has supported on comparable roofs, and how the job is run. Treat it as background reading rather than legal advice. Whether consent is needed is for B&NES Council to decide.
Why leadwork is treated carefully on a listed building
Listing protects a building's special character, and the roof is part of that. In a Georgian terrace the parapet, the hidden gutter behind it and the pitch of the slope behind that were designed together. The lead is not an add-on. It is the material that makes the arrangement work, because it carries water from the slopes and the flat roofs over to the downpipes without showing from the street.
When lead is renewed, the aim is to leave the building looking and behaving as it did. That means the same lengths and positions of joints, the same shape of rolls and drips, the same pattern of falls, and a metal that weathers to the same grey. A change in any of these can alter how water moves across the roof as well as how the roof looks.
There is a practical side too. Old lead often shows its age in a characteristic way: cracks at the drips, creep down the slope, splits across the rolls. Understanding why the old work failed is part of the specification for the new. Our page on the causes of a leaking valley goes through the common failures in one of the most exposed positions.
Consent: the question to ask the council first
Listed building consent in Bath is granted by B&NES, and it sits apart from planning permission. Its own guidance says to speak to the planners before work begins and warns that going ahead without consent is a criminal matter.
What the guidance does not do is set a list of repairs that are automatically exempt. We do not decide this on the owner's behalf, and neither should a roofer. Instead, the sensible approach is a short sequence.
- Find out what is there. A survey of the lead, with photographs of each area, shows what exists, in what condition, and in what detail.
- Describe the proposed work. A written specification says what will be removed, what will be laid, in which material and to what pattern.
- Ask the council before ordering. The B&NES conservation team can say whether the work as described needs consent. The council publishes how to reach them on its listed buildings web page.
- Keep the answer in writing. Whatever the council decides, keep it with the paperwork for the house.
A repair that mirrors the existing metal and layout is simple to put to the planners, whereas a change in material, thickness pattern or detailing is the kind of proposal that most clearly needs agreement. The question is always the council's to answer.
If consent is needed, allow time for it before the scaffold is booked. A roof that is leaking now can be made safe in the meantime without changing its character.
What like for like means for lead
Like for like is a description of the work, not a guarantee of approval. For lead, it has several parts.
Same metal
New sheet lead replaces old sheet lead. It is laid in the same positions and weathers in the same way. A substitute such as GRP or zinc is a change in material, and on a listed building that is a conversation with the council. Our comparison of lead substitutes sets out what each can and cannot do, and the page on alternatives on a listed roof deals with the exceptions.
Same weight, chosen on evidence
Lead is graded by code, the standard marking for sheet thickness, and each position on a roof has a code that suits it. We do not publish code thicknesses on this site, because they belong with the specification for your roof. What we do is measure and record what the old lead was, check it against the position it sits in, and say whether it was right. If the original was too light for its job, a like-for-like replacement would repeat the failure, and the explanation to the council is that the new code is chosen to last in the same detail.
Same joints and falls
On a traditional lead roof, sheets are limited in length so that they can expand and contract without tearing. Joints run with the fall as rolls, and across it as drips or steps. The Lead Sheet Association guidance reproduced by the Building Conservation Directory sets cover flashings to be wedged into the wall at intervals of no more than 500 mm. Following those patterns is what keeps a new roof moving freely. Squaring up or lengthening sheets to save time is the most common source of early cracks.
Same surrounding material
Lead is only as sound as the stone and mortar it is tucked into. Lime mortar is the usual partner for lead in old walls, since hard cement can damage the stone around it. A lead cover flashing set in a hard modern mortar is a mismatch, and the repair should use lime to stay in harmony with the walls.
Traditional details worth keeping
Much of what makes old leadwork last is in the detail, and these are the features a good specification records.
- Wood-cored rolls. A timber batten sits under the lead, which is dressed over it to form a raised joint. Water runs either side of the roll, and the lead can slide at the join.
- Drips. On a flat or low-pitched lead gutter, a step in the deck at set intervals shifts water from one level to the next and lets each sheet expand separately. They are not decoration. A gutter laid without them, or with too few, will stretch and crack.
- Welts and seams. Where lead meets lead at a joint across the fall, a folded seam locks the sheets without solder.
- Stepped and cover flashings. At a chimney or against a wall, lead is turned into raked-out mortar joints and wedged with lead wedges, then pointed. The flashing sits over soakers (small lead pieces interleaved with the roof covering) so that water is carried out and over rather than in.
- Secret gutters. A concealed gutter between a parapet and a slope is part of Bath's roofscape. Our page on the secret gutter covers how that works.
- Fixings. Non-ferrous clips and copper nails are used, because steel fixings rust and stain the lead.
These details do not show from the pavement, and that is exactly why they are sometimes lost when an inexpensive repair is carried out in a hurry. A modern strip stuck over a failed joint may keep out the water for a season, but it takes the original detail out of service.
What the Trust has supported on comparable Bath roofs
We found no published B&NES policy on re-leading listed roofs, so there is no rule to quote here. What exists is casework: the Bath Preservation Trust comments on individual applications, and those comments show how the question is approached. They are examples, not policy.
Its comments on number 33 St James's Square, a house with the highest listing grade, welcomed the valley gutters being relaid in new lead and the asbestos slates being stripped out. It took the opposite view of artificial slate on a terrace at Lambridge Place and backed natural Welsh slate there. The common thread for leadwork is that the Trust looks at what shows from outside, what the original material was, and whether the work keeps it. Where lead is concerned, the original is what it favours.
Reading cases like these helps if you are preparing an application, because they show what a consultee notices: the covering, the visible edges and the soundness of the stonework around the lead.
Patination, appearance and the first year
New lead is bright and silvery. Over months it dulls to the familiar soft grey as a surface layer forms. In the first weeks, rain can wash a white deposit from new sheet onto stone below, and on a listed building with soft limestone that staining is unwelcome. A treatment of patination oil applied at the end of the job can prevent it. We set this out in our page on lead patination oil and white staining.
Appearance matters on a listed building for another reason: a conservation officer will look at how the finished work sits against the old. Lead that goes on in a flat, uniform sheet looks different from lead that has been dressed over rolls and into drips. Lead that has a protective coat on the day of completion weathers more evenly than lead left bare to the first rain.
Tell the council what you intend to do about finish when you describe the work, and tell your roofer too. It is a small item on the specification and avoids a surprise after the scaffold has gone.
How we run listed leadwork
Our approach on a listed roof is to record first, specify second and work third.
- Survey. We inspect the lead from the roof, photograph each area of your own roof, and note the code, the joint pattern and the condition.
- Specification. We write up what is to be renewed and what kept, in the same terms the council will read.
- Consent route. You take that document to B&NES, or we help you prepare it. We explain what is needed, but the decision belongs to the council.
- Make safe if needed. A leaking valley or gutter can be covered while consent is sorted out. Leaks are dealt with ahead of everything else.
- Work. The lead is laid to the agreed detail, the surrounding stone is pointed in lime where that is part of the job, and we clear the site and carry off the waste.
Before the survey, photograph any old lead you can see from the ground, along with drip marks or staining inside, because those pictures help the officer judge the original detail. Our lead roofing hub lists every lead job we take on. Call 01225 285181 or use the enquiry form to arrange a survey.