How heavy is lead sheet per square metre?

Sheet lead is graded in numbered codes, 3 up to 8. Every code is a thickness, and the thickness fixes the weight of a square metre. The table below comes from Royston Lead's cast-lead brochure, checked in October 2026. The colour mark is how a roofer tells the codes apart on site, which matters when several rolls sit side by side on a scaffold and a wrong pick would cost an afternoon.

Notice how the steps run. Each code up adds roughly five kilograms to a square metre, so the heaviest sheet is a little more than two and a half times the weight of the lightest.

Weight scales with area. Ten square metres of code 4 comes to roughly 204 kg, and the same area of code 6 is about 300 kg. A flashing along a chimney may be only a fraction of a square metre, though, since it is a narrow strip. The sums matter most on a flat lead roof, a large dormer or a long box gutter, where the area runs into several square metres.

Roofers also allow extra for laps, upstands and offcuts, so the amount delivered is more than the plain area. We work this out from the survey measurements, and the written quote carries the total. If you are comparing quotes, ask which code each one allows for, since a lighter sheet over the same area uses less metal but may not suit the detail. Our guide to lead codes explains how that choice is made.

A full roll of lead is heavy, and cut sheets are clumsy to haul up a ladder or along a roof. That affects how the job is planned: materials go up by hoist or scaffold, not on a shoulder. The weight also needs a sound deck beneath it. On a flat roof, a lead covering sits on boards or plywood that must be solid and level, so we check the deck on the survey before anything is ordered, and say if boards need replacing first.

Weight has another side. Lead is valuable and awkward to remove, but thieves strip it all the same, as any owner who has had a roof stripped can tell you. Heavier sheet does not stop a determined thief, so do not choose a code with that in mind. Choose it for the detail, and let the survey decide. If lead has already gone from your roof, the make-safe comes first and the permanent repair is specified once the exposed edges have been inspected.

Royston's brochure sets out where each code is used, across five kinds of detail. Code 3 is recommended for soakers only. Code 4 suits small soakers, flashings, pitched valleys and dormer work, though the brochure does not list it for the larger gutters. Codes 5 and 6 cover everything except soakers. Codes 7 and 8 are listed for the valleys, gutters and dormers, and are left out of the flashing column, where a thick sheet would be hard to fold.

So a bigger number is not automatically better. A thick sheet is hard to fold into a tight flashing, and a thin one wears quickly in a gutter. Our answers on lead soakers and the lead code for valleys go through two common cases. Your own roof may call for different codes on different details, and the quote names each one so nothing is left to guesswork.

Lead is sold by weight, so a heavier code costs more per square metre of roof. The price moves with the metal market, so we do not quote a price per kilo here. Typical figures for whole jobs depend on the roof and the survey.

Checkatrade's roof repair guide, updated October 2026, lists lead flashing repairs at £50 to £70 per metre, with VAT on top. After the survey, the written quote sets one total price covering the lead, the fixing and the finish, and it names the code used for each detail. For the full subject, start at the lead roofing and leadwork hub. If you only need a small repair, the lead involved may weigh very little, and the time and access make up most of the cost. Bring the quote you have been given, if there is one, and we can talk through which code it assumes and whether that suits the detail.