Roof coverings part 03 - Lead sheet coverings and flashing

Lead sheet coverings and flashings 

Milled lead sheet is manufactured to BS 1178:1969 'Milled lead sheet and strip for building purposes'. A range of six sizes of lead sheet, defined by thickness in millimetres, is provided for in this Standard (see Table 9.5). A colour coding system is used to enable easy identification of thicknesses. 

Lead sheet is supplied by the manufacturer cut to the dimensions required, or in large sheets, the largest sheet size being 2.4 m wide by up to 12 m long. Lead strip is defined as cut to widths from 75 to 600 mm. 

Lead strip is supplied in coils and is the most common form of lead sheet used, being convenient for flashing and weathering applications. 

Fixing accessories for external leadwork 

The following accessories are normally associated with the fixing of lead sheet in the traditional manner.

Copper clips 

Copper clips should be cut from copper sheet not less than 0.6 mm thick and conform to BS 2870.

Nails 

Nails should be copper clout nails with jagged shanks conforming to BS 1202 Part 2, Table 2. They should not be less than 25 mm long or 10 SWG shank diameter. 

Screws 

Screws should be of brass or stainless steel to BS 1210. They should be not less than 25 mm long or 10 SWG. 

Solder 

Solder for making fixing dots, angles and other seams should conform with BS 219 grade D or grade J. 

 Lead sheet sizes

Outputs in m2 -hour for fixing

Underlay 

The underlay used to isolate lead roofing, cladding and gutter linings from their substrates is impregnated felt or waterproof building paper. Impregnated felt should be used where the surface is not perfectly even. Where the surface is even, waterproof building paper to BS 1521 class A would be suitable. 

Outputs 

Ranges of squad outputs for lead sheet coverings are given in Table 9.6. The outputs include hoisting, cutting and fixing lead per square metre as measured. Ranges of squad outputs for lead flashings are given in Table 9.7. The outputs include hoisting, cutting and fixing lead per linear metre as measured. 

Outputs in metres-hour for fixing