What are lead soakers and where are they used?

At any point where a roof slope finishes against a taller wall, the covering has to be sealed to the brickwork. Chimney stacks, party walls and the sides of dormers all create this joint. A soaker is the part of the seal that lives under the covering. It is a rectangle of lead bent into an L, with one leg lying flat beneath the tile or slate and the other turned up the face of the wall.

The turned-up leg is hidden behind the flashing. The flat leg is held down by the course above and rests on the course below. Water running down the wall, or blown in behind the flashing, lands on the soaker and is carried out over the face of the covering instead of soaking into the roof.

On a plain-tiled or slated roof, one soaker goes in with every course. Each is cut a little longer than the course it serves, so that it overlaps the soaker below. They are fitted as the covering goes on, which is why they are woven into the roof rather than added afterwards.

Above them sits the stepped flashing, a lead strip pushed into a slot raked out of the wall and cut to follow the rise of the courses. The flashing covers the upturned leg of each soaker and closes the gap at the wall. Our page on lead flashing and pointing explains how the upper strip is fixed into the wall, and lead valleys covers the neighbouring detail where two slopes meet. The wider family of work sits under lead roofing.

Soakers are small and sit in tight places, so they use lighter lead than a flashing does. In the lead sheet codes published by Royston Lead and Leadworx, Code 3 is 1.32 mm thick and about 14.97 kg per square metre, and Royston describes it as recommended for soakers only. Code 4, at 1.80 mm, is also listed for soakers and is used where a little more thickness is wanted.

Thin lead bends easily around a tile edge and lies close to the roof surface. Thick lead can lift the covering above it and leave a gap. The trade-off, discussed in our guide to the lead code for flashing, is that the lighter code gives less margin if the roof is neglected.

Soakers fail quietly. Old ones are often thin, and over decades they split along the fold where the lead was first bent. Some were cut too short, so the overlap between courses is barely enough, and a little movement opens it. In a few houses they were never fitted, and the flashing was asked to do everything alone.

Because they are hidden, the first sign tends to be damp indoors: a damp mark on the chimney breast, or a brown patch on the ceiling next to the stack. By then the water has been getting past for some time. Fresh pointing or a new stepped flashing laid on top of failed soakers will look right and leak again, because the fault is underneath.

Roofs where the covering has been lifted for another reason, a slipped slate or a cracked tile, give a useful chance to look at them while the course is open.

Replacing soakers means lifting the covering beside the wall, one course at a time, which is why it costs more than a surface repair. The aim is to fit new soakers in every course and then reinstate the flashing over them. Where only a short stretch has failed, the lifted area stays small. Where the whole side is tired, one visit is cheaper than coming back in a year.

Checkatrade's October 2026 repair guide lists stepped lead flashing at £80 to £120 per metre, ex VAT. That covers the flashing only and leaves out the soakers beneath, so it shows the order of magnitude and nothing more.

You cannot see soakers, but you can see what they leave behind. Look at the line where the roof meets a stack or a side wall. A dark streak running down the brickwork, flaking paint on a chimney breast indoors, or moss that grows thickly along one edge of the slope all suggest water is finding a way in along the joint.

Check the loft too, if you can reach the area with a torch. Timber beside a chimney that feels damp, or has dark rings where drips have dried, tells the same story. Take a photograph before the weather dries it out, because a stain that has dried can be hard to read later.

Our survey photographs show the wall edge and any lifted tiles, so you can judge the condition before deciding anything. Only the fault that needs fixing goes into the plan. After the survey the price comes as a written total. Our 10-year workmanship guarantee is put on paper, and when the scaffold is struck nothing is left behind in the garden.

If you can see a stain beside a stack from inside, send us a photograph of it and of the roof around it. That is usually enough to tell us whether we are looking at the flashing alone or at the courses beneath it.