The cost turns on one question that gets asked far too late: are the existing slates going back on, and how many of them will survive being taken off?
Knutsford has a great deal of older slated property, and "our roof is getting on" is one of the most common opening lines we hear. The cost question that follows has an unusual shape on a slate roof, because the biggest single variable is not the size of the roof — it is what happens to the slates that are already on it.
Slate itself does not really age in the way people assume. Good natural slate comfortably outlasts the person who paid for it. What ages is everything holding it on and everything behind it.
The commonest reason a slate roof reaches the end of its life. Every nail on the roof went in at the same time and has sat in the same conditions since, so they corrode at broadly the same rate and fail at broadly the same time. The symptom is slates slipping in ones and twos, in unrelated places, with no storm to blame.
Once that is general there is no repair that solves it. Refixing the slate that slipped does nothing for the several hundred either side of it that are on the same clock, and you are paying for access every time.
Poorer-quality slate can split into layers as water gets into the cleavage planes and freezes. Slates go soft, flake at the edges, and eventually break up. This one is a property of the material rather than the fixings, and where it is widespread the slates are not worth reclaiming.
The battens carry the fixings; the felt behind them is the second line of defence. Old bitumen felt embrittles and tears, especially at the eaves. Once it has gone, every slipped slate is a leak indoors rather than an inconvenience.
On a slate re-roof there are three routes, and they price quite differently.
The old covering is stripped and disposed of, and the roof is covered in new material. Simplest, quickest, and the most predictable to price. The finished roof is uniform — which on a building that stands alone is fine, and on one of a pair or a terrace can look conspicuously new beside its neighbour.
The slates are sorted as they come off. Sound ones are kept, the rest discarded, and new or reclaimed slate bought in to make up the difference. Often the reclaimed material goes on the prominent elevation and the new goes on the back, so the face the street sees keeps its character.
This is the route that suits most Knutsford period property, and it is worth being clear that it is not a saving. Sorting, grading and re-holing all take labour, every slate is handled twice, and you are still buying material for the shortfall. What you are buying is continuity of appearance.
Where the existing slates will not survive but a weathered appearance is wanted, reclaimed slate can be bought. Good reclaimed slate is in demand and priced accordingly, its remaining life is unknown in a way new slate's is not, and every piece needs re-holing.
| All new | Reclaim and supplement | Bought-in reclaimed | |
|---|---|---|---|
| Material cost | Known and predictable | Reduced, partly | High |
| Labour | Lowest | Highest — double handling | High — re-holing |
| Appearance | Uniform, obviously new | Retains character | Weathered |
| Predictability | Best | Depends on survival rate | Depends on supply |
| Remaining life | Full | Mixed | Unknown |
| Suits the conservation area | Case by case | Usually best | Usually good |
The whole of Knutsford town centre is a conservation area, and the St John's conservation area carries an Article 4(2) direction confirmed in 1995, which withdraws permitted development rights that would otherwise apply.
For a straight re-slate this changes nothing: putting slate back on a slated roof does not materially affect external appearance, so under section 55 of the Town and Country Planning Act 1990 it is not development and no permission arises. Where it matters is if you are thinking of using something other than slate — and that is a conversation to have with the council before ordering materials, not after.
If the building is listed, listed building consent applies separately and does cover roof coverings. That should be resolved before the work is priced.
Re-slating renews a thermal element, which engages regulation 23 of the Building Regulations 2010: the thermal performance of a renewed element must be improved where technically and economically feasible. Approved Document L Volume 1 gives 0.16 W/(m²K) for a roof in an existing dwelling. The work is notified to building control or self-certified under a competent person scheme, with a certificate issued on completion.
We will get on the roof, handle some slates, and give you an honest view of how many are likely to survive being taken off — because that number, more than anything else, determines what your roof will cost. If reclaim is not worth doing on your slates, we will tell you that rather than quote for it and discover it later.
We will tell you honestly what proportion is likely to be reclaimable and whether reclaim is worth doing on your roof.
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It varies enormously with the original quality and the age of the roof, and nobody can give you a reliable figure without handling them. Expect meaningful losses, and expect every surviving slate to need re-holing because it will not line up with new battens at a new gauge.
Not usually, and this surprises people. The material is free but the labour is not — sorting, grading, re-holing and double handling all take time, and you still have to buy new slate to make up the shortfall. Reclaim is done for appearance and continuity, not for economy.
The tell is slates slipping in different places over several years with no storm to explain them. That is nail fatigue — the fixings reaching the end of their life across the whole roof at once — and no repair addresses it.
Not for a like-for-like re-slate: it does not materially affect the external appearance of the building, so it is not development at all under section 55 of the Town and Country Planning Act 1990. Changing to a different covering is another matter, particularly inside the town centre conservation area or the St John's Article 4(2) area.
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 Knutsford, 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
