CareHomeDeskCareHomeDeskWhat a full strip-and-recover re-roof actually involves, what triggers Building Regulations approval, and whether the salvaged tiles or slates coming off the roof are worth putting back.
A full strip-and-recover follows the same broad sequence regardless of covering type: strip the existing tiles or slates, underlay, and (where present) old battens back to bare rafters; inspect the exposed rafters, purlins and any timber sarking or decking, and repair or replace anything defective before covering it again; install new underlay; fix new battens to the correct gauge for the new covering; then refix tiles or slates, including all ridge, hip and verge detailing. The inspection-and-repair step in the middle is the reason a full re-roof takes materially longer than a patch repair and isn't simply 'the same job but the whole roof' -- it's the only point in the roof's life where the structure underneath the covering is actually visible and can be properly assessed, and skipping a thorough check at that stage to save time is a false economy that shows up as a problem again within a few years.
UK Building Regulations approval is specifically required where 50% or more of a roof's area is being replaced, or where the works alter the roof's insulation or ventilation arrangement -- this is a genuine regulatory trigger, not a discretionary judgement call, and it should be factored into the programme and cost of any re-roof being scoped at or near that threshold. A spot repair covering a small percentage of the roof, by contrast, doesn't typically trigger this. If a quote describes 'repairing' a large section that in practice amounts to half the roof or more, treat it procedurally as a re-roof requiring the appropriate approval, not as a repair.
There is no single published British Standard or NFRC age threshold that says a pitched roof must be re-roofed at a specific number of years -- the trigger is the extent of deterioration, not a birthday. Widespread, distributed defects (multiple slipped or cracked tiles across different areas of the roof, degraded battens found during any access, repeated flashing failures) point toward a full re-roof being the better long-term value than an accumulating series of patch repairs, each of which carries its own access and scaffolding cost. A roofing trade term worth knowing, with a caveat: 'nail sickness' is commonly used to describe corrosion of the original fixing nails in an older slate roof, causing slates to slip as the nail head corrodes away -- this is widely used trade terminology, but it could not be verified against any British Standard, HSE, NFRC or BRE document in this research, so treat it as a useful diagnostic concept from experienced contractors rather than a defined technical term with a formal test behind it.
It's tempting to assume the tiles or slates coming off a roof during a strip-out can simply go back on a new underlay and battens, but the realistic salvage rate is commonly around half of what comes off, because cut pieces at hips, valleys and abutments generally can't be reused, and further breakages happen during removal and handling regardless of how carefully it's done. Complex roof shapes with more hips and valleys yield a lower salvage percentage than a simple gable roof. For natural slate specifically, there are concrete viability rules worth knowing before assuming reuse is an option: fixing holes must be re-drilled 50-60mm in from the original hole position rather than reused, slates narrower than 250mm generally can't be reused at all, and a slate that has already been re-holed once before cannot be reused a second time. Beyond the mechanics of reuse, every salvaged tile or slate has already been through however many decades of freeze-thaw cycling the original roof endured -- a slate that looks sound isn't necessarily one with decades of remaining service life left in it. And matching salvaged material to what's already on a roof -- colour, source quarry or manufacturer batch, weathering pattern -- is genuinely difficult to do at any scale without an uneven, patchwork result becoming visible from the ground. None of this is a reason to rule out reuse on principle (it can be the right call, particularly on a conservation or heritage building where matching the existing material matters more than uniform new stock), but it should be treated as a genuine trade-off to discuss with the contractor up front, not an automatic cost saving.
A full re-roof is the point at which the underlay type gets decided, and that decision changes how much roof-void ventilation the roof needs under BS 5250 (see the companion Underlay and Felt article for the detail). Because this is decided once and then lives under the tiles for decades, it's worth getting right at the point of a full re-roof rather than defaulting to whatever the contractor's standard spec happens to be -- ask specifically which underlay classification (breathable/LR or traditional/HR-equivalent) is being installed and what eaves and ridge ventilation provision goes with it.
A full re-roof is a longer, more disruptive undertaking than a spot repair by the nature of the extra inspection-and-repair step described above -- the roof structure is genuinely open to the weather for longer, and scaffolding stays up longer. I could not find a verifiable published figure (from HSE, NFRC or BRE) for typical re-roof duration or noise levels to quote here, and none is given as a result -- any duration estimate should come from the specific contractor's programme for the specific roof, not a general figure. What is worth planning for regardless of duration: while any part of the roof structure is exposed, HSE's core fragile-roof principle applies directly -- 'all roofs, once fixed, should be treated as fragile until a competent person has confirmed that they are non-fragile' -- meaning access and fall-protection precautions should if anything be more conservative during a strip-back than during routine maintenance on an intact roof, not less.
CareHomeDesk gives you compliance checklists, maintenance logs, and contractor management tools built around exactly this kind of knowledge.