Welsh slate
HomeBuilding puts its typical life at 100+ years.
Slate roofing in Farnborough
Slipped slates, tired nails and whole slopes re-hung
We count the slipped and cracked slates, check the nails, battens and lead, then show you the photos and give one written price.
- Photos and measurements
of your roof - One written
price - Repairs, re-roofs
and emergencies - 10-year workmanship
guarantee
What a failing slate roof looks like
- Slates slipped in lines down a slope
- Copper or lead strips holding slates on
- Slates flaking or splitting into layers
- Damp below a valley or chimney
- Light between slates seen from the loft
The slates we lay and repair
Spanish slate
A natural slate HomeBuilding gives 75-100 years.
Fibre cement slate
A man-made slate, listed by HomeBuilding at 30-40 years.
Slate work we take on
Slipped slate refixing
Nail sickness re-hangs
Full re-slating
Slate ridges and hips
Lead valleys on slate
Slate verges
Refix, re-hang or new slate?
Refix
A few slates have slipped and the rest hang firm on sound nails.
Re-hang
The nails have failed across a slope but the slates themselves are still hard.
New slate
The slates are flaking, cracked or too thin to put back up.
Slate roofing, the figures
Slate roofs, measured against the published figures
Pitch limits, slate lifespans, fixing rules, Farnborough's weather, lead codes and the consent tests, each taken from a named standard or guide, with what it means when we survey a slate roof.
| No. | Chapter | The figure it turns on |
|---|---|---|
| 01 | How slate keeps the rain out | 20° minimum for natural slate |
| 02 | Welsh, Spanish, reclaimed or fibre cement | Welsh slate: 100+ years |
| 03 | Nail sickness, tingles and the ridge line | BS 8612:2018 for dry ridges |
| 04 | What Farnborough's weather asks of slate | About 715 mm a year |
| 05 | Lead in valleys, soakers and flashings | Code 4 for valleys and flashings |
| 06 | Re-slating, consent and the 50 per cent line | Under 50 per cent of the roof |
Chapter 01 of 06
How slate keeps the rain out
The limits a natural slate roof is laid within
- 20°Lowest roof pitch for natural slate under BS 5534
- 25°Hooks are ruled out on slopes flatter than this
- BS 5534:
2014 The current code for slating and tiling+A2: 2018 - AD C para 6.8Each slate needs a fixing suited to the job
A slate roof is a set of thin stone plates hung in overlapping rows on battens, the horizontal timber strips fixed across the rafters. Each slate sits over the joint between the two slates below it, so rain running off its face lands on another slate and never on bare timber. The overlap from one course to the course two rows down is called the head-lap, and it is the main thing standing between a driven shower and your loft. Under the battens lies the underlay, a membrane that catches anything blown past the slates and leads it down into the gutter.
The panel sets the limits for that system. BS 5534, the British Standard code for slate and tile roofs, sets 20° as the lowest pitch for natural slate, according to the slate producer Cupa Pizarras. Flatter than that, water can be pushed up through the laps faster than it drains. Cupa adds that hooks are not to be used where a slope is flatter than 25°, so a roof between the two angles is nailed.
The figure25°the lowest pitch at which Cupa says slates may be hung on hooks20° slate minimum25° hooks allowedSource: Cupa Pizarras, citing BS 5534
Nailed slate and hooked slate
A nailed slate hangs from nails driven through holes near its head or part way down its length, depending on how the roof was set out. A hooked slate rests in a wire hook fixed into the batten, and the tail of the hook shows at the bottom edge of the slate. Hooks leave the slate unholed and are quick to fit, but they are visible on the face of the roof, which can matter on a front slope in a conservation area. Our guide to slate hooks and nails compares the two in more detail.
Approved Document C, the part of the Building Regulations covering moisture, asks for every slate, tile and sheet on a roof to be held by a fixing suited to it. BS 5534:2014+A2:2018 is the current code a roofer works to in order to show that a fixing meets that test, although the code itself is guidance and not law.
Small roofs, shallow angles
Pitch is easy to overlook on the smaller roofs of a house: a porch, a bay, a lean-to over the kitchen or the cheeks of a dormer. Those are the places where slate laid too flat shows itself, with damp at the wall junction or a stain a short way into the ceiling below. No repair can change the angle of a slope. Where a small roof sits below 20°, the options narrow to a covering made for that lower angle or rebuilding that small roof in another form. We put a gauge on the slope before suggesting either.
The rest of the roof is detail work. The ridge is the capped line along the top, the hips are capped outside corners, the valleys are the inside corners that carry water off two slopes at once, and the verge is the finished edge at a gable end. Each has its own fixing rules, and chapter 03 sets them out.
Chapter 03 of 06
Nail sickness, tingles and the ridge line
| Part of the roof | Published rule | Source |
|---|---|---|
| Ridge and hip units | Mortar alone no longer relied on since the 2014 revision | BS 5534, as Marley explains it |
| Dry ridge, hip and verge | Systems tested to the specification | BS 8612:2018 |
| Every slate and tile | Fixed in an appropriate manner | Approved Document C, para 6.8 |
| The code itself | Installing to BS 5534 isn't required by law | Marley |
Slate rarely wears out first. The nails that hold it often do. When nails corrode through, slates let go one by one and slide down the slope, and because nails of the same age fail at much the same time, the slipped slates tend to show in lines or scattered across a whole elevation. That pattern has a name in the trade: nail sickness. The slates may still be hard, flat and good for many more years. What has failed is the fixing.
Tingles: the fix for a few slates
A single slipped slate cannot be renailed in place, because the nail holes sit under the course above. The usual repair is a tingle, a strip of copper or lead nailed to the batten through the gap between two slates, then folded up over the tail of the replaced slate to hold it. One or two tingles on a slope are a normal, tidy repair. A slope covered in them is a different matter: it tells you the nails have gone across the roof and more slates are on their way.
At that point, refixing one slate at a time costs more over a few years than stripping the slope, setting the sound slates aside, renewing the battens and underlay, and hanging the slates back on new nails. Our guide to nail sickness on slate roofs walks through how that decision is reached.
Ridges, hips and verges on slate
The table lists the rules that apply when the top and edges of a slate roof are worked on. Ridge and hip units used to be bedded on mortar alone. Since the 2014 revision of BS 5534, as Marley explains it, mortar on its own can no longer be relied on to hold them, so each unit also gets a mechanical fixing. A dry ridge, held by clips and a roll in place of a mortar bed, is the other route, provided the system has passed testing to BS 8612:2018.
Ridge fixing
2014BS 5534 revision: mortar alone no longer relied on
BS 8612:2018 The test specification for dry ridge systems
A slate verge, the edge at a gable, is usually finished with a mortar fillet or a slate undercloak. Cracked verge pointing lets wind under the end slates, which is where storm damage on a slate roof often starts.
Marley also notes that installing to BS 5534 isn't required by law. The legal duty sits in Approved Document C, whose requirement is that every slate is secured in a suitable way. Slating to the standard is the recognised evidence that it was.
From inside the loft, nail sickness can show as rusty nail tips, slates sagging between battens or chinks of light along a course. We look from both sides of the roof before deciding which repair fits.
Chapter 04 of 06
What Farnborough's weather asks of slate
Met Office long-term averages for the South Farnborough climate station
- 715 mmRainfall in an average year
- 118 daysDays with 1 mm or more falling
- 53 daysDays with an air frost, on average
- 1991-2020The period the averages cover
The Met Office station at South Farnborough records average rainfall of about 715 mm a year, spread over around 118 days with a millimetre or more, plus around 53 air-frost days. Those are the averages for 1991 to 2020. They do not make Farnborough unusual. They do describe what a slate roof across Rushmoor and the Hampshire and Surrey border works through every year: plenty of wet days, and enough frosty nights that trapped water can freeze and do damage. A slate that sheds water quickly copes with that easily. A slate kept wet by moss, a blocked valley or a sagging batten does not.
Moss, delamination and frost
Moss grows where a slate stays damp, often on the shaded side of a roof and around chimneys and valleys. It holds water against the slate and can lift the tails, and when it washes down it ends up in the gutters and valleys, where it chokes the flow. Hand brushing is the gentle way to shift it. Marley's guidance rules out high-powered jet washes: they are not recommended, it says, as the force can spoil a slate's surface and cut its life considerably.
Some slates also start to come apart in layers, a fault called delamination. The face flakes or blisters, and the slate thins until it cracks. Delaminating slates cannot be put back on a re-hung roof, so we count them before deciding how many new or reclaimed slates a job needs.
The gutter takes every litre that runs off the slates. A gutter full of moss or silt overflows down the wall or backs up under the bottom course, and a slate roof can be blamed for a leak that began at the eaves. Clearing the gutters is part of any slate repair we carry out, and the fascia boards behind them are checked at the same visit.
When a storm brings slates down
Wind gets under a slipped or loose slate and can strip more from around it. If slates come down, ring your insurer before anything else, photograph the damage, keep every receipt and get a temporary repair in place. Whether the event qualifies is a matter for your policy's own storm definition, read alongside the facts. The Financial Ombudsman says rain, hail or snowfall by itself can constitute a storm. The Ombudsman's guidance adds that a complaint is unlikely to succeed where the roof was already in bad condition and the owner knew about it, so slates lost to long-standing nail sickness may not be covered. We make a leaking slate roof safe first and send you close-up photos of every gap.
Chapter 05 of 06
Lead in valleys, soakers and flashings
| Code | Thickness | Royston lists it for |
|---|---|---|
| Code 3 | 1.32 mm | Soakers only |
| Code 4 | 1.80 mm | Soakers, flashings, pitched valley gutters, dormers |
| Code 5 | 2.24 mm | Flashings, pitched and box valley gutters, dormers |
| Code 6 | 2.65 mm | Flashings, pitched and box valley gutters, dormers |
Slate and lead go together on older roofs. Wherever a slate slope meets a wall, a chimney, a dormer or another slope, lead does the waterproofing. Valleys, the internal corners where one slope runs into another, are lined with lead that the slates on either side overhang. A soaker is a small bent piece of lead slipped under each slate where a slate slope abuts a wall. A flashing is the strip dressed over the top of the soakers and tucked into a mortar joint in the brickwork, called the chase. Between them, these three pieces keep water out of the joints a slate cannot cover on its own.
Choosing the code
Each lead code stands for a weight and a thickness, and Royston Lead's figures for the codes found on slate roofs are in the table. Royston restricts Code 3, the thinnest at 1.32 mm, to soakers. Code 4, at 1.80 mm, is the lightest it lists for flashings and pitched valley gutters. Codes 5 and 6 cover flashings and valleys too, and box valley gutters as well. Approved Document C points to BS 6915:2001 for lead sheet roofing.
Lead flashing can last for over 80 years, on MyJobQuote's figure, which makes that a lower bound rather than a promise. Lead grows and shrinks with the seasons and needs room to do so. Over-long pieces, or lead nailed down too hard, split along the folds or tear at the fixings, and that is where an otherwise sound valley starts to let water through.
When the leak is not the slate
A damp patch by the chimney breast, or a stain on the ceiling directly below a valley, often points to the lead rather than the slates. The faults we find are flashings that have dropped out of a chase where the mortar has failed, valley lead that has split or thinned, and soakers cut short or never refitted by an earlier roofer. Debris matters as well: anything collecting in a narrow valley pushes water sideways under the slates on either side.
At a chimney, the stack has its own top. Flaunching is the angled bed of mortar the pots sit in, shedding rainwater away from the crown of the stack, and cracked flaunching lets water down inside the brickwork, where it can show as a stain that looks like a roof leak. We check it while the scaffold is up.
When slates are stripped for a re-hang, the lead at the valleys and abutments is checked and replaced where needed while the slope is open. For lead beyond the slate, such as bay tops and flat lead roofs, see our lead roofing and leadwork service.
Chapter 06 of 06
Re-slating, consent and the 50 per cent line
The Planning Portal's re-roofing test and its weight rule
- Under 25 per centof the whole building envelope affected
- Under 50 per centof the roof affected
- 15 per centor more heavier: approval and a structural check
These are the Planning Portal's figures for when re-roofing needs a Building Regulations application. Normally none is needed if less than 25 per cent of the total building envelope and less than 50 per cent of the roof is touched by the work. A full re-slate takes the job over the 50 per cent mark, which brings in building control, either through the local authority service or a registered building control approver. For addresses in Rushmoor and Hart, the council service is the Hart and Rushmoor Building Control Partnership, which works from Rushmoor's offices in Farnborough and answers on 01252 398715.
Further afield, Bracknell Forest Council includes new coverings on pitched and flat roofs in its list of jobs that may also need approval, so we check before re-slating a house there. The weight rule applies everywhere: if the replacement outweighs the old covering by 15 per cent or more, approval is needed, and the Planning Portal wants the rafters looked at first by a structural engineer or surveyor. That test matters when fibre cement is swapped for natural slate, since the rafters were sized for the lighter roof.
Planning, listing and conservation areas
Swapping the covering on a house usually falls under Class C permitted development, which means planning permission is not required. Flats get none of those rights. Listed homes keep their Class C rights, but listed building consent is needed for any work that changes the character of the building. Rushmoor has nine conservation areas, among them St Michael's Abbey, South Farnborough and the two 2025 areas, Farnborough Hill and Farnborough Street, and in Hart the 1998 Article 4 directions cover works affecting a frontage roof slope in most of its conservation areas. Hart also says repairs to non-listed buildings need no permission when carried out in a traditional manner with the same materials. Our post on re-slating a period home in a Farnborough conservation area follows that route in detail.
The figure50%of the roof: re-slating past this line brings building control in25% of the envelope50% of the roofSource: Planning Portal, re-roofing guidance
What a re-slate involves
On a re-slate, the slates come off by hand and the sound ones are stacked on the scaffold for reuse. Battens and underlay are renewed, lead is checked, and the slates go back on new nails, topped up with matched slate, before the ridge and verges are fixed. Where scaffold stands on the highway, Hampshire County Council requires the scaffold firm to apply for the licence for you, at least ten clear working days ahead. GOV.UK bat guidance lists re-roofing and roof repairs among the jobs where bats can be disturbed, so we look for signs of them before the first slate is lifted. Our guide to re-slating a roof covers each stage, and our roof replacement service covers a change of covering.
Standards this slate guide draws on
- BS 5534:
2014 Code of practice for slating+A2: 2018 - BS 8612:
2018 Dry ridge, hip and verge systems - BS 6915:
2001 Lead sheet roofing, via Approved Document C
Find out what your slates need
Book a slate survey: we count the slipped slates, test the nails and lead, and send you the photos from every slope.
Typical UK prices for slate roofing
| Job | Typical UK range |
|---|---|
| Fitting a slate roof, national average (MyJobQuote) | around £7,800 |
| Welsh slate, supply only (HomeBuilding) | £185 per m² |
| Spanish natural slate, supply only (HomeBuilding) | £72 per m² |
| Reclaimed Welsh slate, supply only (HomeBuilding) | £90 per m² |
| Three-bedroom semi re-roofed in plain concrete tiles, for comparison (HomeBuilding) | £10,000 to £15,000 |
Source: MyJobQuote slate roof cost guide (October 2026); HomeBuilding new roof cost guide (September 2025)
These are national cost-guide figures for the UK, not what we charge. Your own figure is one total price, put in writing once we have surveyed the roof; check any quote includes VAT and scaffolding.
Slate roof guides and answers
Nail sickness, tingles, reclaimed and fibre cement slate, costs and re-slating, each written for owners of a slated house.
Guide · 9 min read
How Much Does a Slate Roof Cost?
Fitting slate costs more than fitting concrete tile, and published supply prices for the slate alone run from…
Guide · 9 min read
Natural vs Fibre Cement Slate
Natural slate outlasts fibre cement slate by decades on published figures, and it usually looks right in conservation…
Guide · 9 min read
Nail Sickness on Slate Roofs
Nail sickness is what happens when the nails holding slates rust through while the slates themselves are still…
- How Long Does a Slate Roof Last?
- Re-Slating a Roof: What Is Involved
- Welsh vs Spanish Slate
- Reclaimed Roof Slates: Pros and Cons
- Can a Slate Roof Be Repaired? What Can Be Fixed
- Slate Hooks vs Nails
- Victorian Slate Roofs: Repair or Re-Slate
- How to Cut Slate Roof Tiles
- Re-Slating a Period Home in a Farnborough Conservation Area
- What Is the Minimum Pitch for Slate?
- What Is a Tingle on a Slate Roof?
- Why Is My Slate Roof Leaking?
- Can Roof Slates Be Reused?
- How Heavy Is a Slate Roof?
- Slate vs Tile Roof
- What Is Slate Head-Lap?
- How Long Do Fibre Cement Slates Last?
- Moss on a Slate Roof
- What Causes Cracked Slates?
- Slate Roofs on Listed Buildings
- Ridges on Slate Roofs
- Felt and Membranes Under a Slate Roof
- Matching Slates for a Repair
- Is a Slate Roof Worth It?
- Can Slating Be Done in Winter?
- What Is Slate Delamination?
- Ventilating a Slate Roof
- Copper vs Aluminium Slate Nails
- What a Slate Roof Survey Should Check
Other roof services for slated homes
How a slate job runs
- Send a photo or describe it
- Slates counted and photographed
- One written price
- Work done, waste cleared, handover
Slate roofing in Farnborough: your questions
What is nail sickness on a slate roof?
It is the point where the nails holding the slates have corroded, so slates slip out of place even though the slate itself is sound. It tends to show as slipped slates across a whole slope. A few can be held with tingles; widespread failure means stripping the slope and re-hanging the slates on new nails.
Should natural slate be swapped for fibre cement to save money?
It can cost less to buy, but HomeBuilding gives fibre cement 30-40 years against 100+ years for Welsh slate. In a conservation area a switch may not be accepted; Basingstoke and Deane says artificial slates are unlikely to be acceptable in four of its areas. We price both where both are allowed.
Is a slate roof dearer than a tiled one?
Usually, on HomeBuilding's September 2025 figures: a three-bedroom semi re-roofed in plain concrete tiles comes in between £10,000 and £15,000, and choosing Welsh slate for that home could push the figure to £18,000. Reclaimed or Spanish slate narrows the gap. What sets your price is the area, the access and what lies under the slates.
Can the slates that come off go back on?
Often, yes. Slates that are still hard, flat and whole can be re-hung on new nails and battens, with matched reclaimed or new slate making up the shortfall. Slates that are flaking, cracked or have worn through at the nail holes are set aside. We count both piles and show you.
Where do the old battens, felt and broken slates go?
They are taken away, not left in your garden. Timber, felt and broken slate go off site as waste, and the scaffold and drive are swept clean before we leave each evening. If old fibre cement slates may contain asbestos, they are wrapped and removed on a consignment note, never thrown in an open skip.
Get your free roof quote
Book a survey of your slate roof
Tell us where slates have slipped or water is coming in, and we will survey every slope.
10-year workmanship guarantee, in writing.