If you're after a roof that'll outlast everything else on your property, natural slate is the answer. A well-laid Welsh slate roof can last 100 years or more — they were building with Penrhyn and Ffestiniog slate in the Victorian era, and those roofs are still going strong today. We lay slate roofs across Hertfordshire for both new builds and heritage restoration projects, and we take genuine pride in getting the craft right.
Slate roofing — whether natural or man-made — requires specialist knowledge that goes beyond standard tiling. Natural slate comes in different grades, thicknesses, and sizes, and each type has its own laying requirements. We work with the main slate types available in the UK: Welsh slate (Penrhyn, Ffestiniog, and Cwt-y-Bugail quarries), which is the finest and longest-lasting but also the most expensive; Spanish slate (SSQ, Cupa, and Del Carmen brands), which offers excellent quality at a more accessible price; and Brazilian slate, which varies significantly in quality and needs careful specification. For each project, we advise on the right slate for the budget, the property style, and any conservation requirements. Natural slate is typically centre-nailed to treated battens over breathable membrane, with copper or stainless steel nails — never galvanised, which corrodes over time. Head nailing is used on lower pitches or more exposed sites. Slates are graded and sorted by thickness before laying, with thicker slates at the eaves and thinner ones towards the ridge — a technique called diminishing courses on traditional roofs. For properties in Watford, where a major town in south-west Hertfordshire with a wide range of housing from Victorian terraces to modern high-rise developments and suburban estates, slate roofing is often the expected material on older properties and may be required by conservation officers. Man-made slate alternatives — such as Marley Edgemere Slate, Tapco, Breedon, and SSQ Riverstone — use composite materials to replicate the appearance of natural slate at roughly 40-50% of the cost. They're lighter, more consistent in thickness, and easier to cut and fix, making them a practical choice where the look of slate is wanted without the premium.
On older slate roofs, the original iron nails corrode over decades, losing their grip on the slates. Individual slates start slipping out of position, leaving gaps in the covering. If nail sickness is widespread, the only real solution is a full strip and re-slate with modern copper or stainless steel nails. Patching with tingles (small metal clips) can buy time but isn't a permanent fix.
Lower-quality slates — particularly some Brazilian and cheaper Spanish imports — can delaminate over time, with the layers of stone separating and flaking apart. This is a material quality issue and usually means the slates need replacing. Welsh slate and high-quality Spanish slate (like Cupa or SSQ) are far more resistant to delamination.
We often see slate roofs where previous repairs used completely wrong slates — different thickness, wrong colour, artificial where the rest is natural. This looks terrible and can cause performance issues if the replacement slates don't sit at the right angle or lap correctly. Matching slates properly matters for both appearance and weatherproofing.
Valleys on slate roofs can be open (lead-lined), swept (slates cut and shaped to follow the valley line), or laced (slates interwoven). Each method needs specific skills. Poor valley work on a slate roof is a common leak point, and swept or laced valleys are a specialist craft that not every roofer can do well.
New slate roofing costs more than standard tiles but the lifespan justifies the investment. Man-made slate on a semi-detached in Watford runs £7,000-£10,000 — comparable to premium concrete tiles. Natural Spanish slate is £10,000-£15,000 for the same property. Welsh slate — the premium choice — is £15,000-£25,000 or more depending on the quarry and grade. Per square metre, expect £70-£100 for man-made slate, £100-£140 for Spanish natural, and £140-£180+ for Welsh natural, all fully installed. These prices include scaffolding, stripping (if re-roofing), breathable membrane, battens, slate, ridges, and fixings. Reclaimed Welsh slate — sourced from demolition or re-roofing projects — is sometimes available at lower cost than new, and we can source this for period restoration work.
Natural slate: SSQ Del Carmen and Domiz (Spanish, 500mm x 250mm standard, blue-black), Cupa 12 and Cupa R12 (Spanish, blue-grey), Penrhyn Heather Blue and Bangor Blue (Welsh, premium), Cwt-y-Bugail (Welsh, mid-range). Man-made: Marley Edgemere Slate, Tapco, Breedon, SSQ Riverstone. Nails: copper clout nails for natural slate (never galvanised — copper outlasts the slate itself), stainless steel ring-shank for man-made. Battens: 25mm x 50mm BS 5534 graded treated softwood. Membrane: Tyvek Supro breathable. Valleys: code 5 milled lead for open valleys, with slate cutting for swept valleys. Ridge: dry ridge system with angular ridge tiles to match the slate aesthetic.
We assess your Watford property's roof — measuring up, checking the existing covering and structure, and discussing your requirements. If it's a conservation area or listed building, we'll advise on the slate specification likely to be required.
We source samples of suitable slates for you to see and compare. We'll explain the differences between Welsh, Spanish, and man-made options — appearance, lifespan, and cost — so you can make an informed choice.
Full scaffolding is erected for safe access. The existing roof is stripped and the timbers inspected. Any rafter or purlin repairs are carried out. New breathable membrane and battens are fixed at the correct gauge for the chosen slate size.
Natural slates are graded and sorted by thickness on site. Laying starts at the eaves with the thickest slates, working up to thinner slates at the ridge. Every slate is individually nailed with copper nails. Valleys, hips, and verges are finished with the appropriate traditional or dry-fix details.
Ridge and hip details are finished, all flashings are fitted, and the roof is checked thoroughly. Scaffolding comes down, the site is cleared, and you receive your guarantee documentation — typically 10 years on workmanship, plus the manufacturer's material warranty.
Slate roofs are found on older properties across Watford, particularly Victorian and Edwardian terraces, villas, and cottages. Watford is a major town in south-west Hertfordshire with a wide range of housing from Victorian terraces to modern high-rise developments and suburban estates. Where the original slate is still in good condition — which is common with Welsh slate, even after 100+ years — maintenance and spot repairs can keep it going indefinitely. Where the slate has reached end-of-life (more common with cheaper original materials or poor-quality imports), a full re-slate is a significant but worthwhile investment. In conservation areas across Hertfordshire, natural slate is often a requirement, and the planning authority may specify the type and source. We're experienced in working within these constraints and liaising with conservation officers on the appropriate specification.
Laying natural slate is a specialist skill, and our team has years of hands-on experience. We grade, sort, and lay slate properly — the traditional way — so it looks right and performs for generations.
We work with the full range of slate options and can help you choose the right one for your Hertfordshire property — factoring in appearance, lifespan, budget, and any planning requirements.
We understand the requirements for listed buildings and conservation areas, including material specifications, approval processes, and the need for sympathetic craftsmanship.
We use copper clout nails on all natural slate work — they outlast the slate itself. Galvanised nails corrode, causing nail sickness. It's a detail that matters enormously for long-term performance.
Welsh slate can last 100-150 years or more — some of the roofs laid in the 1800s are still going strong. High-quality Spanish slate lasts 75-100 years. Man-made slate typically lasts 50-60 years. The lifespan depends on the quality of the slate, the quality of installation, and the exposure of the site. Either way, slate outlasts every other roofing material by a significant margin.
Man-made slate: £7,000-£10,000 for a semi-detached. Natural Spanish: £10,000-£15,000. Welsh slate: £15,000-£25,000+. The cost is higher than concrete tiles, but spread over a lifespan of 75-150 years, slate is actually excellent value. We provide detailed quotes after a full survey, with no hidden extras.
Welsh slate — from quarries like Penrhyn and Ffestiniog — is the finest roofing slate available. It's incredibly dense, splits cleanly, and has a beautiful blue-grey or heather colour. It lasts 100+ years. Spanish slate is also excellent quality, slightly less consistent in colour and thickness, and costs roughly half as much. Both are natural products and far superior to cheap imports.
Often, yes. Conservation area rules in Hertfordshire typically require roofing materials to match the existing character of the area. If surrounding properties have natural slate, the planning authority will usually insist on the same. We can liaise with your local conservation officer to confirm the requirements for your specific property.
Yes — reclaimed Welsh slate is available from specialist salvage suppliers and can be a cost-effective way to get premium slate at a lower price than new. The slates need sorting and grading carefully, and some wastage is normal, but reclaimed Welsh slate still has decades of life left in it. We can source and assess reclaimed slate for your project.
Modern man-made slate is excellent. Products like Marley Edgemere Slate and SSQ Riverstone look very convincing on the roof and come with 40-50 year warranties. They're lighter than natural slate (which is easier on the roof structure), more consistent in thickness, and significantly cheaper. If you want the slate look without the premium price, man-made is a solid choice.
Copper clout nails — always. Copper doesn't corrode and will outlast even the longest-lived slate. Galvanised nails seem fine initially but corrode over decades, leading to nail sickness where slates start slipping. We've re-roofed properties where the slate was perfect but the galvanised nails had rotted away. Using copper from the start avoids this entirely.
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