Re-slating means taking the old covering off a roof and putting a new one on, and on a slate roof that is a slower, more exacting job than a tile re-roof. Every slate is cut, holed and nailed by hand, the laps between courses are measured with a gauge, and the details at the hips, valleys and abutments are formed on site. Most of what decides whether the new roof lasts is hidden under the slates and done before the first one goes up. This guide walks through the stages in the order they happen, so you know what to expect from the scaffold going up to the last bucket of rubbish leaving the drive.
Before anything comes off: the survey and the decisions
A re-slate starts on paper. Someone has to go up, look at the roof close to, and decide what is wrong and what has to be done about it. On a slate roof that means checking whether the slates are sound or delaminating, whether the fixings have rusted, how the battens and any sarking (the boards or felt laid across the rafters) have fared, and what condition the lead, chimneys and ridge are in. Some roofs turn out to need only repair, and our guide to whether a slate roof is worth repairing covers that choice.
If a re-slate is the right answer, three decisions follow. The first is the covering: the same type of natural slate, a different origin, reclaimed slate, or a man-made product. Our comparison of natural and man-made slate covers that choice. The second is what goes under the slates, because a new underlay and ventilation arrangement is part of a proper job. The third is the paperwork, which depends on the extent of the work and the type of house.
The written quote should set all this out, with the slate named by origin and size, the fixings named, the underlay named and any provisional items for timber repairs identified. A quote that says only re-slate roof, price, tells you nothing about the quality of what you will get.
Permissions and building control
Re-covering a roof does not always need a building control application. The Planning Portal's test is that work affecting under 25% of the building envelope and under 50% of the roof is not normally notifiable. A whole-roof re-slate goes past the 50% line, so approval is generally needed, and the insulation of the roof as a whole may have to be upgraded. Heavier slate than the old covering, by 15% or more, also means the structure is assessed. You can read the detail in the Planning Portal's re-roofing guidance, and your building control body confirms how it applies. The application and the inspections are ours to arrange when your job needs them.
If the house is listed, or stands in a conservation area, a change of material or appearance may need consent. Like-for-like replacement is usually acceptable, but check with your council's conservation officer before you order anything. Nesting birds and bats in a roof are protected, so work may need to be timed or surveyed first.
Scaffold, protection and stripping
Slating is done from a full scaffold with a working platform at eaves level and a boarded stage or edge protection at the lifts. Slates are heavy and sharp-edged when broken, and nobody should be working on a steep pitch from a ladder. The scaffold also gives a place to stack materials and a safe route for waste. Gutters and ground-level plants are protected before work begins, and neighbours should be told when the scaffold is going up.
The strip is done a slope at a time, not all at once. The old slates are lifted off by cutting or pulling the nails, sorted into piles and either set aside for reuse or discarded. Ridge and hip tiles come off at the top. The battens are removed along with the old underlay. By the end of the day the exposed roof is covered with tarpaulins or a temporary membrane, because rain on an open slope can do more damage in an hour than the old roof did in a year. This is the stage where a good roofer works methodically and a rushed one leaves the loft open to the weather.
What the stripped roof reveals
With the slates gone, the roof structure is visible in a way it has not been for decades. This is when the hidden problems turn up and the quote's provisional items come into play. We look for rafters that have rotted at the feet where a leaking gutter has soaked them, wall plates that have gone soft, timbers eaten by woodworm or beetle, and old repairs that were done in a hurry. Where sarking boards are damp or rotten, they are replaced. Where there is no sarking and the roof has felt, the felt is renewed.
Fascia boards, eaves details and bargeboards can be replaced now, while the access is in place. So can the lead flashing around chimneys and dormers, because new lead should be installed at the same time as the new slates, not squeezed in after. If the chimney needs repointing or a new flaunching at the pot, the scaffold makes that cheaper than at any later date. The aim is for the new covering to sit on a sound, true structure, with every detail around it renewed to last as long as the slates.
The depth of this stage is why a fixed quote has to be honest about unknowns. A good estimate includes a sum for timber repairs and says how extra work will be priced if it is needed, with photographs, before it is done. Surprises are normal on old roofs. What matters is how they are handled.
Underlay, ventilation and battens
Next comes the layer most people never see again. A breathable underlay or a traditional membrane is laid over the rafters, running horizontally from the eaves upwards, with overlaps that shed water. It is the second line of defence if wind-driven rain or snow gets under a slate. At the eaves it dips into the gutter so that water is carried out and not onto the fascia. Ventilation is detailed at the same time, with eaves vents and ridge or slate vents so the roof space can breathe. Our guide to underlay and ventilation on slate roofs explains why a slate roof that cannot breathe suffers from condensation and rot.
Battens then go on. These are timber laths, treated and graded, nailed across the rafters at a spacing worked out from the length of the slate and the head lap, which is the amount each course overlaps the slate two courses below. The spacing is called the gauge, and on a slate roof it is calculated for the roof, not read off a chart. The bottom batten is set to the correct height at the eaves, and the first course is doubled so that water runs off the lower edge cleanly. Accurate battens give straight courses, even lap and a roof that looks right as well as shedding rain.
Laying the slates
With the battens fixed, slating begins at the eaves and works up. Each slate has two nail holes, drilled in the factory or punched on site, and is fixed with copper or stainless steel nails. Where a roof is exposed, or the slates are thin, a hook or clip at the tail may be used as well; our page on slate hooks and nails sets out when each is right. Slates are laid in broken bond, meaning that the joint between two slates sits over the centre of the one below, so water cannot find a straight line down.
The edges and junctions are where the skill shows. At a verge, the slates may be cut to follow the line of the gable, bedded and pointed, or fixed dry with a purpose-made system. Hips can be finished with a mitre (slates cut and set to meet in a clean angle) or with a ridge-style cap. Valleys carry lead or a manufactured valley trough with slates cut tight to its edges. Around chimneys, soakers (small lead tabs that interleave with each course) and stepped flashings keep the abutment dry. Slate vents, where used, are set in the slope in line with the courses. This is slow work, and it is the reason a re-slate takes longer than a tile roof of the same size, as our page on how long re-slating takes explains.
Cost and what moves it
Published guides give typical UK ranges of £120 to £180 per m² for a natural slate re-cover and £90 to £130 per m² for man-made slate; the survey comes first and the firm price after it. Those ranges cover the labour and materials for the strip, battens, underlay, slates and finishing. They rarely include scaffold, which is priced separately and rises with the height and the number of sides of the house, or the extra cost of timber repairs, lead renewal and chimney work. Complex roofs cost more per square metre than plain ones, because every hip, valley, dormer and abutment needs hand-cut slates and lead. The cost of getting the detail right is mostly labour, which is why the price of the slate alone is a poor guide to the price of the job. Our page on what a slate roof costs takes the figures further.
Ridge, finishing and handover
The ridge is the last major job. Under current practice, ridge and hip components are fixed mechanically, with BS 5534:2014 expecting mechanical fixing and not mortar alone, and dry-fix systems tested to BS 8612:2018 are common. The ridge can be capped in clay, slate or lead, depending on the house. Roof lights, vents and flue terminals are fitted back in line, and the lead is dressed and checked.
Before the scaffold comes down, we walk the roof, check every course and every detail, clear the gutters of slate dust, and make sure nothing is left behind. Then the scaffold is struck, the drive and garden are swept, and the old slates and timbers go away with us. You are shown photographs of the finished work, and the written guarantee follows. If you want a visit to talk through your own roof, pick up the phone on 01256 213956 or write to us on WhatsApp, and have a look at slate roofing in Basingstoke for the rest of our slate work.
