Slate roofs get replaced too early more often than too late. The covering and the things holding it on have wildly different lifespans, and confusing the two is expensive.
Macclesfield has a great deal of older slated property, much of it silk-era and much of it originally covered in Welsh slate. Welsh slate is among the most durable roofing materials ever used in this country, and that fact is the source of most of the confusion about when these roofs need replacing.
The confusion is this: people treat "the roof" as one thing with one lifespan. It is not. It is several systems with wildly different lifespans, stacked on top of each other — and the one you can see from the street is usually the one that lasts longest.
| System | What it does | Typical life |
|---|---|---|
| The slates | Shed water | Longest by far — a century and often much more in good Welsh slate |
| The fixings | Hold the slates on | Decades; the usual first failure |
| The battens | Carry the fixings | Decades; fail with water or old nail damage |
| The underlay | Second line of defence | Shortest, in older bitumen felt |
Read that table again, because it contains the whole answer. In a typical old slate roof, three of the four systems will need renewing several times before the slates themselves are worn out. A roof that is failing is usually a roof whose fixings, battens and underlay have gone — with a covering on it that has decades left.
Slates slipping in ones and twos, in different places, over several years, with no storm to account for them. Every nail on the roof went in at the same time and has sat in the same conditions since, so they fail together. Once it is general there is no repair: the slates either side of the one you refix are on the same clock, and you pay for access each time.
Visible from the loft on a bright day. Old bitumen felt goes brittle and tears, particularly at the eaves where it has been carrying water and taking daylight through the gutter gap. Once it has gone, a slipped slate is a leak indoors.
Split along the nail line, or soft where water has been sitting. If the battens have gone, everything above them has to come off to renew them.
Press the rafter ends where they meet the wall plate — the first place to go, because that is where a failing gutter deposits water. Soft timber means the job has grown beyond roofing.
A different question, and the one that decides whether you are buying new slate or relaying your own.
A handful of poor slates on an old roof is entirely normal and means nothing. What matters is the proportion. Where most of the roof rings sound and looks solid, the slates are worth keeping.
If the roof has failed but the slates are sound, there is a third route between patching and a full new covering: strip the roof, renew the battens, underlay, fixings, lead and insulation, and relay the original slates.
It is not a cheap option — every slate is handled twice, sorted, graded and re-holed, and you buy in material to cover the losses. But it can come in below a full roof of new Welsh slate, and it keeps the appearance of the building exactly as it was. Inside the High Street or Christ Church Article 4(2) areas — where Cheshire East states that owners will find it necessary to apply for planning permission for most external alterations — keeping the appearance unchanged has value beyond the aesthetic.
It is worth asking for it to be priced alongside a new covering, so you can see the difference rather than assume it.
Everything above pushes towards not replacing a slate roof prematurely, and that is the right instinct. But there is a real cost to leaving it too long, and it is not about the slates.
Once the underlay has perished and the fixings are going, water reaches the battens and then the rafters. At that point the job stops being a re-roof and becomes a re-roof plus carpentry, and the slates you were protecting get handled during structural work rather than a clean strip — which is when breakage rates climb.
The sweet spot is the point where the fixings have clearly gone but the timbers are still sound. That is when the slates come off cleanest, the survival rate is highest, and the job is purely roofing.
Whichever route you take, renewing the covering renews a thermal element and engages regulation 23 of the Building Regulations 2010, which requires thermal performance to be improved where technically and economically feasible — 0.16 W/(m²K) for a roof in an existing dwelling under Approved Document L Volume 1. Where the roof space is a habitable garret room rather than a loft, that insulation has to go at rafter level, which needs planning into the specification from the start.
The work is notified to building control at Cheshire East Council or self-certified under a competent person scheme, with a certificate issued at the end.
If your slates have years left in them, we will tell you — and price the job that keeps them.
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Very much longer than the nails holding it on. Good Welsh slate on a well-built roof will comfortably see out a century and frequently a good deal more. It is normal for a roof to need renewing two or three times over the life of its slates.
The roof, probably. The slates, probably not. Slipping across the whole roof with no storm to explain it is nail fatigue — the fixings failing. That means the battens, underlay and fixings need renewing, but the slates themselves may be perfectly sound.
Tap one. Sound slate rings; a dead thud suggests it has taken on water and is delaminating. Look for flaking at the edges, slates splitting into layers, and slates that have gone soft or lost thickness. A handful of poor ones is normal; widespread delamination is not.
Water reaching the timbers. Once rafter ends and battens start to rot, the cost of the eventual job rises and the work extends from roofing into carpentry.
Apex Roofing covers Cheshire and the surrounding area for complete roof replacement, new slate and tiled roofs and re-roofing.
Apex Roofing Cheshire · 105 Fence House, Fence Avenue, Macclesfield SK10 1LM
Tell us about the property and the roof in Macclesfield, and we will come back to you — usually the same day.
Prefer to talk? Call 07377 461095 · WhatsApp +44 7465 861265 · Email apexroofing14@gmail.com
