Leadwork

BS EN 12588 Code 3–8: thicknesses (1.32mm to 3.55mm), weights (14.97 to 40.26 kg/m²), colour coding system (green=3 to orange=8), application guide by element, thermal expansion calculations

LEADSKILLS Levels 1–3 (introductory to heritage), approved training centres, NVQ equivalencies, CSCS card routes, LCA membership vs individual certification, why heritage clients specify LCA certified leadworkers

Lead vs zinc (severe corrosion), lead vs aluminium (severe), lead vs copper (mild), lead vs stainless (negligible), separation methods (bituminous felt, EPDM, neoprene), run-off separation requirements

Internal and external angle bossing step-by-step, wood-cored roll with copper rivets (max 150mm spacing), annealing at 150–200°C, tool list (bossing mallet 450g, bossing stick, chase wedge), Code 4 minimum for bossing

Four-element chimney set (back gutter, step-and-cover sides, front apron), Code 4 throughout, back gutter 75mm wide minimum, step soakers at each tile course, front apron 150mm up chimney and 150mm onto tiles

Cheek flashings, back gutter (75mm depth, 150mm width minimum, Code 4), back gutter outlets, step-and-cover at cheek/roof junction, thermal movement provision per element, common failure modes

Copper clout nails (40mm × 3.35mm) or stainless clips, 500mm maximum centres (450mm exposed), lead tack minimum 50mm × 50mm Code 3, why zinc/galvanised fixings cause electrolytic failure, substrate pull-out values

Code 5 minimum, bay maximums (Code 5: 2,250mm × 675mm; Code 6: 3,000mm × 850mm), hollow roll 50mm × 50mm minimum, drip 50mm minimum, dog-ear corners, fall 1:80 recommended

Code 4 minimum, 1,500mm maximum bay, tack fixing at 500mm centres, bossing vs machine-forming, saddle and gusset pieces at valley/hip junctions, common split and lifting failure modes

Minimum 150mm width (225mm for catchments over 50m²), Code 5 standard, falls 1:80 minimum, drips at 1,500mm maximum, outlet sizing by BS EN 12056-3 catchment calculation, mandatory overflow sump

EWC code 17 04 03 (hazardous), consignment notes and registered carrier, scrap value £1–£1.80/kg, CLAW Regulations 2002 OEL 0.15 mg/m³, no dry cutting/grinding, blood lead monitoring thresholds

Code 3 soakers with Code 4 cover flashings, soaker sizing formula (gauge + lap + 25mm), cover flashing 65mm minimum into joint, 75mm lap, maximum 1,500mm bay length, pointing materials (lead wool preferred)

Lead expansion coefficient 29.3×10⁻⁶/°C, UK roof temperature range −10°C to +80°C, bay limits by code (Code 3/4: 1,500mm; Code 5: 2,250mm; Code 6: 3,000mm), failure diagnosis from undersized bays

Open vs closed vs swept vs woven valley types, minimum 150mm clearance width, Code 4 standard (Code 5 for large catchments), maximum 1,500mm bays, 50mm drip height, catchment area calculation method

Listed Building Consent for material substitution, like-for-like code weight matching (Code 6–8 on pre-1900 buildings), LCA Heritage certification, conservation officer pre-application advice, natural vs artificial patination