Is Lead Flashing Dangerous?

Lead harms the body when it is taken in, either swallowed as dust or flakes or breathed in as fine dust or fume. A strip of flashing sitting on a chimney or against a wall is neither. It is a solid sheet, high up, that nobody touches from one year to the next, and the dull grey crust on its surface is a stable coating that forms as the metal weathers.

The picture changes when lead is worked. Cutting, scraping, sanding and above all burning or welding release dust and fume at head height for whoever is doing the job. That is why lead work on a roof suits a trained person with the right kit, and why a keen amateur with a blowtorch is a bad idea. The Health and Safety Executive publishes guidance on lead for anyone who works with it, and it is worth reading before any cutting.

Children and anyone who is pregnant deserve particular care around lead dust, so keep them away from the work area. Off-cuts, old flashing and dust from a job should leave the site with the waste rather than sit in a garden or skip bag at ground level.

If you do pick up a piece of lead, for instance an offcut left after a repair or an old strip that has dropped into the gutter, the sensible habits are simple. Wash your hands properly afterwards, before you eat, drink or smoke, and do not hold it in your mouth, which sounds obvious until you are halfway up a ladder with a clip or nail in your teeth. Work clothes that have been near cutting should be washed apart from the family wash.

Keep lead pieces away from small children and pets. A chewed strip is a different matter from a flashing left alone on a wall.

When we work on lead we cut and dress it with hand tools where we can, keep the work area clear and take every offcut and scrap away with the waste. Dust from a chase being raked out before new lead goes in is cleaned up rather than left to blow across the lawn. You should expect the same from anyone you hire: ask how they cut and dispose of lead, and how they keep the garden clear. A roofer who shrugs at the question has told you something.

Water running off a lead roof can pick up traces of the metal, which matters if you collect rain in a butt or a tank. We would not use that water for drinking, for filling a paddling pool or for edible plants, and we would think twice about watering a vegetable bed with it. For a flower border or washing the car the worry is much smaller, but if the water is going anywhere near food or people, speak to a water specialist about the installation first.

The stretch of roof matters. A downpipe fed by a long run of lead, such as a valley or a flat roof drain, gives a different answer from a small flashing around a chimney, where the lead area is tiny against the tiled slopes around it. Even so, the safe habit is to treat water from any roof with lead on it as water for the garden, not the glass.

If you are planning a harvesting system, tell the installer what the roof is made of before they quote.

You are not expected to test or inspect lead yourself. What you can do from the ground is notice when flashing has gone wrong: strips lifting off a wall, split folds, white powdery patches or stains running down the brickwork. None of that is a health emergency, but a failed flashing lets rain into the roof, which is a good reason to have it seen. Our answer on white residue on lead flashing covers the powdery coating, and lead stolen from a roof covers theft.

When a flashing needs work, we survey it first and send you photos of the actual strip, the wall and the joints, which show exactly what we found. One total price, in writing, follows that survey. Lead that comes off is bagged and removed with the other waste, and nothing is left lying on the roof or in the garden overnight, so there is nothing for children or pets to find.

You can read about everything we do with the metal on our lead work page.