Why Lead Still Matters
Nothing has replaced lead for complex detail work — valleys, chimney flashings, soakers under slates, aprons over bay windows, cheeks and tops of dormer windows. It's soft enough to dress into awkward shapes by hand, strong enough to handle a hundred years of British weather, and chemically inert so it doesn't react with surrounding materials. Code 4 (1.80mm) handles most domestic flashings. Code 5 (2.24mm) is used for valleys, bay tops, and anywhere with heavier duty. Code 6 and above are commercial and church roofing.
All the lead we fit meets BS EN 12588 — the current British Standard for rolled lead sheet. We don't cut corners by using sandcast "heritage" lead that's half the thickness of what's required.
Lead Valleys
Where two roof slopes meet at an internal angle, the valley takes the combined runoff of both slopes — huge volumes of water during heavy rain, plus any debris that washes down. Properly fitted lead valleys are bulletproof; botched ones are the single biggest cause of roof leaks on older Sheffield properties.
A correctly formed lead valley uses code 5 lead in maximum 1.5m lengths (longer and thermal movement tears the lead), laid over a timber valley board, with welted edges up each slope and a proper lap between sections. The slates or tiles above are cut to a clean parallel line and bedded so water runs off centrally rather than under the edges. Most lead valleys that fail were either too long between laps, had the laps the wrong way round, or had slates bedded directly onto the lead with mortar (which scours the lead as it weathers).
We re-form lead valleys as a stand-alone repair, or as part of wider roof work. Typical cost for a single valley replacement with scaffold access is £800 to £1,400.
Dormer Cheeks & Tops
Dormer windows — the ones that project out from the main roof plane — have cheeks (the side walls) and tops (the small roof over the dormer). Both need proper lead dressing at every junction. Common problems include cracked lead at cheek-to-top corners (from thermal movement), failed soakers under adjoining tiles, and apron flashings that have slipped because they were fitted with nails through the face rather than chase-wedged in.
We renew dormer leadwork using traditional welted and bossed techniques — no silicone, no lead-coloured flashband patches over the top. It's slower than botched alternatives but results in a watertight finish that will outlast anything stuck on with sealant.
Chimney Flashings
Chimney flashings are covered in detail on our chimney repair page, but the lead-specific points are worth noting here. Flashings need to be chased into the brickwork at least 25mm deep, wedged with lead wedges, and pointed up with lime mortar (never cement, which goes hard and tears the lead as it moves). Step flashings up the sides of a chimney should be cut to lap over the adjacent slates or tiles and turn up the stack at least 75mm. A common botch is a single-piece straight flashing instead of stepped — it never stays watertight.
Lead Theft & Replacement
Lead is still a target for organised metal theft, though less than it was ten years ago. If your property has had lead stolen, the replacement should include lead-marking paste (SmartWater or similar) on every new piece, which makes resale at scrap yards impossible. We also recommend mechanical fixing of ridge and valley pieces beyond what traditional specification calls for — hidden stainless steel cleats bolted into the structure.
Insurance companies handle lead theft claims readily — we provide the detailed loss assessment report and supply replacement quotes in their standard format.
