Lead Soakers

Soakers are pieces of sheet lead (or sometimes other metal) bent to an L-shape and laid between each course of slates or plain tiles where the roof abuts a wall, chimney or dormer cheek. One leg lies flat under the slate or tile; the other turns up the wall. A stepped cover flashing, let into the mortar joints of the masonry above, is then dressed down over the upturned legs. The combination of soakers and stepped cover flashing is the traditional British and Irish abutment detail and the equivalent of North American step flashing with counter-flashing.

Layout

UK building control guidance notes that soakers should be roughly the same length as the slates, each fitted over the slate or tile beneath it so that the fixings of the covering above do not puncture the soaker below. The stepped cover flashing is laid over the line of soakers to direct water down the roof to the gutter.

Lead codes

UK lead sheet is specified by "code" numbers related to thickness and weight. Guidance from the Lead Sheet Association, as cited by LABC, gives Code 3 as the minimum for soakers and Code 4 as the minimum for cover flashings, with heavier codes for exposed locations. Lead flashings are typically limited in length to allow for thermal movement.

When soakers are used

Soakers suit small-format, flat coverings such as natural slate and plain clay or concrete tiles, which lie flat enough for the soaker to sit between courses. Profiled single-lap profiled tiles are usually finished with a lead cover flashing dressed over the tile profile, or with proprietary abutment flashings, rather than soakers.

Alternatives

Lightweight lead substitutes and proprietary flexible flashings exist; their use depends on the covering manufacturer's instructions and local acceptance.