Lead in construction

[edit] What is lead?

Lead is a naturally occurring chemical element and a dense, soft, malleable metal. It has been used in construction and engineering for thousands of years due to a combination of properties that make it easy to work and durable in service, including:

• High density.
• Low melting point.
• Ductility and malleability.
• Resistance to atmospheric corrosion.
• Good acoustic insulation properties.
• Ability to provide protection against ionising radiation.
• Ease of fabrication and recycling.

The harmful effects of lead have been recognised since antiquity, although scientific understanding of chronic lead poisoning and regulatory controls developed primarily during the nineteenth and twentieth centuries. As a result, the use of lead has become more restricted, particularly in applications where human exposure may occur.

[edit] Construction applications

Lead was used for making water pipes in the Roman Empire, and production subsequently expanded throughout Europe and Asia. Across Europe, lead production revived during the eleventh and twelfth centuries, when it was increasingly used for roofing and plumbing.

Historically, lead and lead compounds were used for roofs, flashings, cornices, tank linings, electrical conduits, cladding, gutters, parapets and water pipes. Lead was also incorporated into soft solder, an alloy of lead and tin used for joining metals.

Although many traditional uses have declined because of health concerns and regulatory restrictions, lead remains an important construction material. Current applications include:

• Roof coverings.
• Flashings and weatherings.
• Valley and parapet gutters.
• Soakers and damp-proof courses.
• Stained-glass construction and restoration.
• Heritage and conservation projects.
• Radiation shielding in hospitals, laboratories and specialist industrial facilities.
• Acoustic insulation in specialist applications.

Lead continues to play an important role in the conservation and repair of historic buildings, particularly churches, cathedrals and listed structures where traditional materials and detailing may be required. Historically, lead-based paints were widely used to protect iron and steel from corrosion. Although their use is now heavily restricted, many older structures still contain lead-based coatings that may require specialist management during maintenance, refurbishment or demolition.

[edit] Health risks

Lead dust, fumes or vapour can be generated when lead-containing materials are cut, heated, abraded, removed or recycled. The body absorbs lead primarily through inhalation and ingestion. Once absorbed, lead circulates in the blood and can accumulate in bones and organs, where it may remain for many years.

Short-term exposure to elevated levels of lead may cause headaches, fatigue, nausea and abdominal pain and anaemia.

Long-term or repeated exposure can result in more serious health effects, including:

• Kidney damage.
• Damage to the nervous system.
• Memory and concentration difficulties.
• Peripheral nerve disorders.
• Elevated blood pressure.
• Reproductive and fertility problems.
• Developmental effects in unborn children.
• Impaired cognitive development in children.

Some inorganic lead compounds are classified as probably carcinogenic to humans.

Pregnant workers and young children are particularly vulnerable to the effects of lead exposure.

[edit] Working with lead

Lead may be encountered in existing buildings, particularly older properties containing lead roofing, flashings, pipework, tanks, solder, stained glass or lead-based paint systems.

Activities that can generate hazardous lead dust, fume or vapour include:

• Abrasive blasting or burning of lead-based paint.
• Removal of old paint coatings.
• Hot cutting during demolition and dismantling.
• Scrap processing and recycling operations.
• Lead roofing work.
• Lead smelting, refining, alloying and casting.
• Manufacture and restoration of stained-glass windows.
• Processing and recycling of lead-containing materials.

In the UK, work involving lead is subject to statutory controls intended to minimise exposure. Employers are required to assess risks, implement appropriate control measures and, where necessary, provide health surveillance and biological monitoring.

Measures that can reduce exposure include:

• Substituting less hazardous materials where practicable.
• Leaving lead-containing paint undisturbed if it is in good condition and adequately encapsulated.
• Using cold-cutting methods in preference to hot cutting.
• Avoiding unnecessary heating of lead-containing materials.
• Using suitable chemical strippers, wet-abrasion methods and dust suppression techniques.
• Wearing appropriate respiratory protective equipment, gloves and protective clothing.
• Preventing the spread of dust through segregation and containment.
• Cleaning work areas regularly using appropriate methods.
• Disposing of contaminated waste safely.
• Washing hands and exposed skin thoroughly before eating, drinking or smoking.
• Avoiding hand-to-mouth and hand-to-eye contact in contaminated areas.

[edit] Lead water pipes

Lead water supply pipes remain present in some older buildings and infrastructure. Although no longer installed for potable water systems, existing lead pipework can contribute to lead contamination of drinking water, particularly where water chemistry promotes corrosion. Replacement programmes continue across the UK, and building owners may choose to replace lead supply pipes as part of refurbishment or improvement works.

[edit] Types of lead

Lead used in construction is typically supplied as:

• Rolled lead sheet.
• Machine-cast lead.
• Sand-cast lead.

Rolled lead sheet is available in a range of codes, typically codes 3 to 8, as defined in BS EN 12588, Lead and lead alloys – Rolled lead sheet for building purposes. The code relates to sheet thickness and weight, with Code 3 having a nominal thickness of approximately 1.32 mm and Code 8 approximately 3.55 mm.

Typical applications include:

• Code 3: Soakers and small flashings.
• Code 4: Flashings and damp-proof courses.
• Code 5: Flashings and gutters.
• Code 6: Roofing and larger gutters.
• Code 7 and Code 8: Long-span roofing, parapet gutters and specialist applications.

When designing lead sheet roofing and weathering systems, allowance should be made for thermal movement. Lead expands and contracts significantly in response to temperature changes, and appropriate bay sizes, fixings and detailing are required to avoid fatigue, splitting and premature failure.

[edit] Regulation and guidance

The use, handling and removal of lead in the workplace is subject to statutory controls intended to protect workers and building occupants from exposure.

In the UK, work involving lead is regulated under the Control of Lead at Work Regulations, which require employers to:

• Assess the risks associated with lead exposure.
• Prevent exposure where reasonably practicable.
• Adequately control exposure where prevention is not possible.
• Provide suitable information, instruction and training.
• Monitor exposure levels where necessary.
• Arrange health surveillance and biological monitoring for workers undertaking certain lead-related activities.

Lead-containing waste generated during construction, maintenance, refurbishment or demolition works must be handled and disposed of in accordance with applicable environmental and waste-management legislation.

The management of lead is particularly important during work on older buildings, where lead may be present in roofing, flashings, pipework, tanks, solder, stained glass and historic paint systems. Refurbishment and demolition projects should identify potential sources of lead contamination at an early stage and implement appropriate control measures.

Lead in drinking water is also subject to regulatory control.

Guidance on the safe use of lead in construction is published by government bodies, health and safety regulators, trade organisations and conservation bodies. Additional guidance is available for specialist applications such as lead roofing, heritage conservation and the management of lead-based paint.

[edit] Related articles on Designing Buildings

• Aluminium.
• Asbestos.
• Construction dust.
• Construction materials.
• COSHH.
• Deleterious materials.
• Flashing.
• Hazardous substances.
• Lead.
• Paint.
• Risk assessment.
• Soldering.
• Spangle.
• Tin.
• Types of roof.
• Volatile organic compounds.

[edit] External resources

• HSE - Hazardous Substances: Lead