Chimney and Flashing Leaks

On a traditional chimney, lead is dressed up the side of the stack in steps, tucked into the mortar joints, and lapped over soakers under the slates. At the front there's an apron, at the back a small gutter (a back gutter) to throw water round the stack.

Leaks come where the lead has lifted, where the mortar holding it into the joints has fallen out, where the back gutter is blocked, or where someone sealed it with silicone or tape instead of lead, which fails within a few years.

Pots, flaunching and stacks

The cement slope at the top (the flaunching) holds the pots. Cracked flaunching lets rain into the stack, and a loose pot in a gale is a danger to anyone below. A leaning stack is an emergency: keep people away and send it now.

Chimneys still in use for coal, peat or wood go through more heat and moisture than capped ones, so their mortar and flashing wear faster. The area pages show how many homes in each area still heat mainly with solid fuel.

Valleys and walls

Valleys between two slopes are lined with lead or a preformed liner. Where an extension roof meets a house wall, the flashing is chased into the wall. Roof windows come with their own flashing kits. All three get the same storm treatment: lifted edges, blocked water, cracked joints.