Lead Weathering Regulations

  • BS 12588 – specifies the codes and standards for sheet lead
  • Lead Sheet Association publishes “Rolled Lead Sheet – The Complete Manual
  • Control of Lead at Work Regulations 1980

Lead Sheets

  • Cast sheet Lead
    • Historic buildings
    • No BS number
    • Sizes and thickness vary
  • Rolled (milled) Sheet Lead
    • BS 12588:06
    • 5% MAX variety
    • Width: 150-600mm (30mm step)
    • Normally 3 or 6m length (12m MAX)

BS12588 Code No

Thickness mm

Weight kg/m2

Color code

Max Length m

3 (lead soakers)

1.32

14.97

Green

1

4 (flashing, chimney back gutter by welding; slate)

1.8

20.41

Blue

1.5

5 (bossing)

2.24

25.45

Red

1.5

6

2.65

30.05

Black

 

7

3.15

35.72

White

 

8

3.55

40.26

Orange

 

Characteristics of Lead

  • Malleability – easily shaped
  • Fatigue – can crack over a period of time caused by expansion and contraction due to temperature change
  • Thermal Movement – high coefficient of linear expansion (29.3×10-6)
  • Creep – will stretch under its own weight
  • Fire-resistant – melts at 327°C
  • Recyclable – 100%
  • Patination – forms a film of a strongly and highly insoluble patina
  • Durability – last for long
  • Corrosion – in contact with mortar, lichen
  • Density – 11.34g/cm3
  • Thermal Conductivity – 34.76W/mºC

Lead Weathering Tools

  • Flat Dresser
  • Bossing Stick
  • Bending Stick – to bend into square or round
  • Setting-in stick – forming corners
  • Bossing Mallet
  • Snips
  • Lead Knife
  • Chase Wedges – moving a sheet lead into a corner or straightening corners
  • Drip Plate
  • Seaming Pliers – folding the lead
  • Soldering Irons – to join 2 lead pipes
  • Shears – to cut a lead sheet
  • Split Rule or Sliding Bevel – to transfer the pitch of the roof to the lead sheet
  • Plugging Chisel – to drive Wedges into the brickwork
  • Shave-hook – to clean welding surface

75mm – MIN vertical overlap for lead parts
1 cement to 4 sand – recommended mortar mix
Large Headed Copper Nails – for fixing sheet lead weathering components
Liver Disorder – long term exposure to lead without protection
Saddle – two parts of an abutment meets at the ridge of the roof

Not to reduce in thickness of more then 25% when bossing

Lead Weathering Fixings

  • 450mm – MAX clip distance (500mm – for shelter conditions)
  • 450mm – MAX space between Wedges
  • Tinned Copper Clips (Lead Clips – for shelter only) MIN 50mm – the most suitable fastening for Code 5 lead
  • 20-25mm – recommended width for lead wedges
  • Brass – used in the manufacture of screws for fixing sheet lead components
  • Stainless Steel Screws + Washer to fix lead into joints > 18mm
  • Lead Silicone Sealant – to fill joints
  • 19mm – MIN length of fixings

Lead Weathering Fabrication

Front Apron

  • 150mm – MIN marking out up stand (75mm – MIN installation up stand)
  • 25mm – into brick-work
  • 150mm – recommended overlap of tiles (200mm – for low pitched roofs) which should be clipped
  • 300mm – MIN size of the roll
  • Lead Welded (Code 4)
    • 150mm– MIN marking out turn around the chimney (100mm – MIN installation)
  • Bossed (Code 4 but Code 5 is preferred)
    • Width of chimney + 300mm - 400mm = recommended length
    • 150-200mm – turns around the chimney
    • 200mm – MIN projects at the sides onto the roof tiles

Step Flashing (Abutment Flashing)

  • Code 4 – Blue (Code 5 – Red when dressing down over deeply profiled tiles)
  • No cuts below 65mm – Water Line
  • 75mm – front apron overlap
  • 150mm – front up stand (200mm – in exposed situations or over deeply profiled tiles)
  • 85mm – steps
  • 100mm – overlap of each peace of length
  • 1.5m – MAX length of flashing
  • Should have Soakers if no Cover Sheet
  • Lead Cleat – securing a step flashing
  • 12mm – gap between the bottom edge and the surface of the tile/slate

Soaker

  • Code 3 - Green
  • 75mm – MIN up stand
  • 100mm – MIN cover of tile/slate
  • 175mm – MIN overall width
  • Margin – slate that can be seen when the roof is completed
  • Gauge – the distance from batten to batten
  • Lap – amount of cover given to a tile/slate
    • The shallower roof – the greater the lap
  • Length of a soaker =
    • (tile/sate length-Lap)/2+Lap+25mm(for fixing) OR
    • Gauge + Lap +25
  • Number of soakers required = (Length of the roof (m))/(Gauge (m))

Back Gutter

  • Cover flashing – the last one to fix
  • 100mm – MIN up stand at rear of chimney behind Cover flashing
  • 200mm – extends to the side onto the roof
  • 100mm – MIN turns around at sides of chimney (Step Flashing overlap)
  • 150mm – sole for collecting debris
  • 500mm – lead roll size
  • Tilting Fillet – wooden strip that supports a lead sheet

Lead Slate

  • Fabricating using Code 4
  • 150mm – MIN vertical up stand at the back and other sides
  • 400x400mm – MIN base plate
    • 150mm – MIN from the up stand to the edge (200mm – in case of single lap tiles)
  • 100mm – MIN slate behind up stand under the tiles
  • 5mm tolerance around pipework (circumference of a circle = πD)
  • Storm Collar – solvent weld to plastic soil or vent pipes
  • Flange – the base of the tube
  • Welt – folding at the back to stop capillary action

Welding

  • Under Cutting – holding the flame in the pool for too long
  • Copper with Acetylene Gas – can produce an explosive compound
  • Size 2 and 3 Blow Torch Nozzles – used for lead 3,4,5 Codes
  • Butted Seam
    • Seam is ½ to 1/3 of sheet lead thickness
    • Penetration is through to underside
    • 10mm – MIN width of the weld for Code 4 Flat Butted weld F
  • Lapped Seam
    • Penetration is not through to underside
  • Acetylene supply should be turned off first
  • Oxidizing and Carburizing flame
  • 0.14bar – pressure on oxy-acetylene bottles

Lead Weathering Health and Safety

  • Employer
    • Access the risk of your health
    • Put in place systems of work and controls (extraction ventilation equipment)
    • Provide washing and changing facilities
    • Tell you about the risk to your health from working with lead
    • Train you how to use protective equipment
  • Employee
    • Make sure you have all the information and training you need to work safely
    • Make full use of all the control measures (barrier cream; lead apron)
    • Follow good and well-tested work practices:
      • Keep your work area clean
      • Clear up and get rid of any lead waste at the end of the day (shift)
      • Do not take home any protective clothing for washing
    • Wear any necessary protective clothing and respiratory protective equipment
    • Report any damaged or defective clothing and respiratory protective equipment to your supervisor
    • Eat, drink and smoke in provided areas
    • Practice the high standard of personal hygiene
    • Keep your medical appointments with the doctor

Lead Joining Methods

  • Wood-cored Roll – flat roofing, pitched and cladding
  • Hollow Roll – pitched roof
    • Laps to join across
    • No abutments
  • Welts – steeply pitched roofs, wall cladding
  • Standing Seam – pitched roofs (≥80º), vertical cladding without angles
    • Where not vulnerable to mechanical damage
  • Drips – flat or low-pitched roof up to 10º
  • Haps – vertical cladding, pitched roof (≥10º)

Lead Weathering Maintenance

  • Patination oil
    • Coat 50mm underside from the edge
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