Slate roofing in Bognor Regis

Slates only keep water out when each one is held to a sound batten at the right overlap and on a steep enough pitch.

A slate roof is a stack of layers, and the slate is only the visible one. Rafters carry the battens. Underlay, a membrane laid under the battens, catches whatever wind pushes past the slates. The slates hang above in overlapping courses, each held at its holes or at its tail. The overlap between one slate and the course two rows below is the headlap, and it is what stops driven rain being pushed upwards and under the slate. It is set from the slate size, the pitch and how exposed the site is. Cupa Pizarras, a slate supplier, gives 115 mm for a 500 by 300 mm slate at 20 degrees in sheltered or moderate exposure. That figure is for that one case, and the headlap for your roof is worked out for your roof, with a little extra where the weather is likely to be hard on it.

2.1 Pitch limits and the low slopes

Slate needs a slope steep enough to shed water. For a 500 mm slate in moderate exposure, Cupa Pizarras reads BS 5534:2014+A2:2018 as setting a floor of 20 degrees, and it also rules out hook fixings on any pitch under 25 degrees. Low slopes are where this bites: a porch roof, a shallow dormer, the lean-to at the back of a terrace. A slope below the limit is better covered in something made for that pitch, such as lead or a flat roof membrane, than in slate that lets the weather back in. The answer on the minimum pitch for a slate roof sets out how the limit works, and it is the first thing we measure on a new extension.

2.2 Nails, hooks and the old-roof caveat

Nails through the holes in each slate are the traditional fix. A hook holds the slate by its tail instead, and the pitch limit above applies to it. Where a roof has fixings of both kinds, the survey notes it and shows the photographs, because mixed fixings often mean an earlier repair that was done differently from the original build. Eaves are checked with the same care. The bottom course has to project over the gutter, and a slate cut too short there sheds water behind the gutter and onto the fascia, a fault that stays out of sight until the timber behind it is soft. Our page on nails or hooks compares them on cost and grip.

BSI itself cautions that BS 5534's advice may not fit some old roofs, especially those laid with traditional or reclaimed slate. So on an older roof we apply the standard with judgement, matching the original build where it still works and improving it where it does not, and we explain the difference in the written quote.

A few slipped slates are a repair. Slates sliding across a whole slope mean the fixings have failed and the roof wants relaying.

Slate fails slowly and in ways you can learn to read. The covering often outlasts the things holding it, so the signs sit on the roof and in the gutter rather than in the stone. Slates on the path, a dark gap in a course, a slate hanging at an angle: each says a fixing has given way. We begin in the loft, where daylight through the roof, damp rafters and wet battens show what the underside is doing, and then go out onto the slope to see what lies behind it.

4.1 One slipped slate or a failing slope

A single slate slips for plain reasons: a gust, a branch, a knock from a ladder, a nail that has finally let go. The remedy is a replacement slate held by a tingle, a thin tongue of lead or copper fixed to the batten above and turned up under the slate's tail so that it cannot slide. Where slates are slipping in different places across the same slope, the nails themselves are failing, a condition called nail sickness, and replacing slates one at a time only postpones the bigger bill. Our guides to why slates slip and what a slate tingle is show each repair step by step.

4.2 Flaking, layering and cracked stone

Some slates fail in the stone itself. They flake, split into thin layers, which is called delamination, or crack across the middle. A handful can be replaced and the roof carries on. When the slates themselves are reaching the end of their life across a slope, the honest answer is a re-roof. Reclaimed slate is one route to a matching repair, though it needs sorting, and a new roof in fresh slate is the other.

4.3 Deciding to re-slate

Re-slating means stripping the slates, sorting them by condition, renewing the underlay and any soft battens, then relaying the good slates with new ones making up the shortfall. It is a replacement of the covering, not a new roof from the rafters up, and it keeps the character of the original. We give the verdict as repair, patch or replace, and we recommend the least work that sorts the fault out for good. Our guide to re-slating a roof follows the stages from the scaffold to the last course.

After a gale, make the roof safe first, photograph the damage and tell your insurer before arranging a repair, keeping receipts for any temporary work. Which? quotes Financial Conduct Authority data showing that a payout followed only 32 per cent of 2024 storm claims, and ordinary wear and tear is normally excluded, so nobody can promise cover. If you disagree with the outcome, take it to the insurer's complaints team and, failing that, the free Financial Ombudsman Service. Our guides to slate roofs in storms and to whether home insurance covers slipped slates go through the steps, and a slipped slate that is left will usually be joined by its neighbours in the next blow.

Like-for-like re-slating rarely needs planning permission, but Building Regulations, listed buildings, scaffold licences and old materials can each apply.

Planning comes first. Under section 55 of the Town and Country Planning Act 1990, work that leaves the outside appearance of the building materially unchanged is not development, so re-covering a roof in matching slate does not usually need planning permission. Listed buildings and Article 4 areas are the caveats. None of Arun's Article 4 directions around Bognor takes away roof rights, but a change from slate to another material can alter the look of a street. The Steyne and Waterloo Square conservation area dates from August 1979, with Waterloo Square added in July 1994, and Aldwick Road was designated in July 1994. Check with Arun District Council's planning team before you change a covering, and send photographs of the roof with your question.

6.1 Listed buildings and the South Downs

Nobody may alter a listed building in a way that affects its character without consent. The Park authority treats routine maintenance and small like-for-like fixes as outside listed building consent. Inside the National Park, the authority decides planning in the Arun and Horsham parts, while the district council deals with applications for it in the Chichester part, so the right door depends on the address. Our answer on listed building consent for re-slating goes through the cases.

6.2 Building Regulations on a re-slate

Under the Planning Portal's tests, re-covering is usually outside building control only when the work touches less than 25 per cent of the building envelope and less than 50 per cent of the roof. A new covering that makes the roof 15 per cent heavier or more also brings building control into play, and the structure is checked before the slates go on. Arun District Council's own page names replacing roof coverings as work it expects applications for, so ask its team or your roofer to confirm. Where the job is notifiable, we explain the consent route and handle the Building Regulations notification. Re-slating can also bring an energy efficiency upgrade: Approved Document L 2021 applies until 24 March 2027, when the 2026 edition takes over. Our guide to re-slating and Building Regulations sets it out.

A scaffold that sits on a pavement comes under the Highways Act, and the licence is issued by the county as highway authority; ask your roofer who puts in the application. West Sussex County Council asks for at least 10 working days' notice and charges £266 for one month; Hampshire County Council, which covers Havant, wants a ten-working-day gap before the start date and charges £211.90 for the first two weeks. Two more checks come before stripping. HSE guidance regards any property built or refurbished before 2000 as likely to contain asbestos, which matters for old garage roofs, soffits and sheet products attached to a slate house. Bats are protected by law as well, and a roost under the slates is easily disturbed by stripping, so we check for signs of one before the first slate comes off. Neither check takes long, and both are far easier to deal with before the scaffold is up than after the roof has been opened.