Re-slating means removing the slates from a roof, renewing what lies under them where needed, and fixing slates back on, some old and some new. It is a bigger job than a repair, and it follows a fixed order because each layer depends on the one beneath. The slope is stripped from the top down, the slates are sorted, the underlay (the membrane under the slates) and then the battens (the cross-timbers that carry each course) go on, and only then do the slates return, fixed and lapped, followed by the ridge and the lead details.
This guide is the process from first survey to final clear-up, plus the regulations that can apply. It does not argue whether you should re-slate at all; that decision is covered in repair or re-slate. For the wider service, see our slate roofing in Stroud page.
The survey that sets the plan for the whole job
Before there is any scaffold, someone has to look at the roof closely, and the findings drive every decision that follows. We measure each slope, note the pitch, and record the slate size and how far the slates overlap. We look at the battens and rafters from the loft where we can, and at the state of the lead, the ridge, the chimney flashings and the eaves.
The survey also answers the question of reuse. Some slates will be sound enough to go back; others will be cracked, laminated or thin from age. How many is only clear once the slope is open, so the written quote prices the new slate that is certain to be needed and states how any extra will be charged if more fails than expected. The survey photographs show your own slopes as they stand, so the starting condition is on record.
Access on a valley-side street
In and around Stroud many houses sit on steep lanes or in terraces with no room for a lorry. We plan scaffold, deliveries and skip placement at survey, because a pallet of slates that cannot reach the house changes the programme. Those arrangements are priced into the written quote rather than found on the first morning. On scaffold, MyBuilder's 2026 guide gives about £1,125 for a re-roof; your own figure depends on height and footprint.
Stripping the old slates and sorting them
With the scaffold up, the roof comes off in stages. Taking the whole slope off in one go would leave the house open to the first shower, so the work is split by slope or by section, and what is stripped in a day is normally covered again by the evening. The lower courses are removed last, so the roof keeps shedding water for as long as possible.
Each slate is lifted by hand, not thrown, and inspected as it comes down. A sound slate rings when tapped and shows no hairline splits. A slate that sounds dull, flakes at the edge or has a nail hole torn through its head is rejected. Slates are then stacked by size, because a roof of mixed lengths cannot be laid at a single batten spacing.
What goes back and what does not
Reusing the good slates keeps the weathered colour of an older roof and cuts the amount of new material needed. The rejects go to the skip, and new slates are brought in to make up the shortfall. On an older roof, new slates are chosen to agree with the old in size, thickness and colour so the slope reads as one. Our slate roof repairs page explains how single replacements are fitted.
Everything that comes off the roof is waste or stock. The old underlay, rotten battens and broken slate are cleared from site as the job goes, and not left in the garden.
New underlay, new battens and the ventilation path
This is the stage that often goes unseen once the roof is finished, and it matters a great deal. With the slates off, the old underlay is stripped and the rafters are checked for rot, movement and woodworm. Any timber that has failed is repaired or sistered before anything new goes on top.
The new underlay is rolled across the rafters from eaves to ridge, each course lapping over the one below, and it is draped slightly between the rafters so water can run off it and not pool. Marley's guidance on cold-roof ventilation, which refers to BS 5250, distinguishes two kinds. A non-breathable (HR) underlay needs a continuous 25 mm gap along the eaves on pitches of 15 degrees or less and 10 mm above that. A breather (LR) underlay above a sealed ceiling asks for much less: ordinary eaves construction at 3 mm is enough. So the underlay we choose decides how the loft is vented.
Battens set to the slate, not the other way round
New treated battens are fixed across the rafters at a spacing worked out from the slate length and the headlap. The first batten at the eaves is set so the bottom slate overhangs the gutter, and the top batten is set so the ridge course sits correctly. A batten gauge that is a few millimetres out at the bottom grows into a visible error by the ridge, so the lines are checked as the roof rises.
Holing, fixing and lapping the slates
New slate is usually supplied holed. Old slate that is going back on may need re-holing, because its original nail holes can be worn or broken. A slate is holed near its head, or about the middle of its length for centre-nailing, and the position decides how much of the slate lies under the course above it.
Nails, not pegs
Slates are fixed with corrosion-resistant nails, normally copper or stainless steel, driven so the head holds the slate without crushing it. Over-driving cracks a slate and under-driving lets it rattle. Nail fatigue, where the fixings corrode and let go, is a common reason an older roof needs re-slating in the first place, so the choice of metal matters. Hook fixings are not for use below 25 degrees, according to Cupa Pizarras' summary of BS 5534, so on a shallow roof a slate that would have been hooked is nailed.
Headlap in a laid roof
The headlap is the overlap between a slate and the slate two courses below. It is what keeps wind-driven rain from being blown under the slate, so it widens as the pitch falls. For a 500 x 300 mm slate in moderate exposure, Cupa Pizarras gives 115 mm at 20 degrees, 105 mm at 22.5 degrees and 95 mm at 25 degrees. Our slate sizes and headlaps guide covers the whole system, so we keep to the practical point here: the gauge is checked against the laps as each course goes on.
Ridge, hips, valleys and leadwork
The ridge caps the apex. A hip slopes down each outward corner of a hipped house, and a valley is the inward fold that gathers water from two slopes into one channel. Each is a place where slates stop and another material takes over, so each gets its own care.
Ridge and hip fixings
Since BS 5534:2014, a mortar bed is not relied on by itself; ridge and hip pieces are held with mechanical fixings too, and BS 8612 covers dry-fix systems that clip or bolt in place without a mortar bed. We fit whichever system suits the roof and the look of the house, and we say which in the quote. On price, MyBuilder gives dry ridge at £40 to £60 per metre, typically £500 to £1,000 a job.
Lead details
Lead is used for flashings (the strips that seal the roof where it meets a wall or chimney), soakers (small pieces that interleave with the slates at an abutment) and valley gutters. Leadworx calls Code 4 its usual pick for flashing, and lists Code 3 for soakers. The code is a thickness: Code 4 is 1.80 mm and Code 5 is 2.24 mm. New lead is normal on a re-slate, because old lead that has been lifted rarely lays down flat again. MyJobQuote describes lead flashing as capable of lasting over 80 years when fitted correctly.
A swept slate valley is formed with cut slates and no lead showing. Our page on slate valleys goes into those details.
How long a re-slate takes
We do not publish a stock number of days, because no two slopes behave alike. The programme is set by the roof area, the number of slopes, how many dormers and chimneys interrupt them, the state of the timbers once the roof is open, and the weather. A small plain gable and a hipped roof with a valley and two stacks are different jobs.
What we can describe is the sequence and where time goes. Scaffold goes up first and comes down last. Stripping and sorting is quick compared with laying, because laying slates course by course, with the gauge checked as it goes, is the slow part of the work. Rafter repairs, if needed, add time, and so does lead, because each flashing is cut and dressed on site.
Weather is part of the schedule
Slating stops in high wind and in heavy rain, since slates and the people carrying them should not be moved on a wet scaffold in a gale. Strong wind also makes it unsafe to leave a slope uncovered. The stripped section is closed with underlay or sheeting every evening, so a delay costs time and not a leak. We give you an expected programme with the quote and tell you as soon as the weather moves it.
Cost scales with area. MyBuilder's slate cost guide gives £100 to £180 per m2 installed, with Spanish slate at £100 to £130 and Welsh slate at £140 to £180, and notes a semi with Spanish slate at £7,000 to £10,000.
When Building Regulations apply to a re-slate
Re-roofing is not always notifiable, but a full re-slate often is. The Planning Portal sets the line at less than 25 per cent of the building envelope and less than 50 per cent of the roof, below which approval is not normally needed. A whole-roof re-slate is over the 50 per cent line, so a Building Regulations application normally applies. We explain what is required and handle the notification, so you are not left chasing it.
Thermal upgrade under Part L
Approved Document L treats stripping a roof down to the rafters and rebuilding as renovating a thermal element. Once more than 50% of the element is renovated, the entire roof should reach the Table 4.3 U-value, 0.16 W/(m2.K). The document notes that if this would limit headroom a lesser standard may be appropriate. So a re-slate can come with added insulation, and your building control body decides what is reasonable for the house.
Weight and listed roofs
The Planning Portal also says approval is needed if the new covering increases roof weight by 15 per cent or more. Heavier replacement slate on a roof built for something lighter calls for a structural check; see Approved Document A. Planning rules seldom bite on a like-for-like re-slate, but a listed house needs the conservation officer consulted before slate is ordered. For the official wording, see the Planning Portal re-roofing page.
The finished roof carries our 10-year workmanship guarantee, in writing.