Roofing

Chimney Leak After a Storm — What to Check Before You Call

Chimneys are the single most common source of storm-related water entry. They sit at the highest, most exposed point of the roof and have four separate failure points — any of which lets water in during a 50+mph storm.

The four most likely causes

1. Lead flashing lifted or split

The lead apron, soakers and back gutter around the chimney base are the primary seal. Storm wind can lift loose flashing edges; expansion over the years splits old lead. Look for shiny lifted edges or visible cracks.

2. Failed pointing on the stack

Sand-and-cement joints over 30 years old erode in driving rain. The whole stack acts like a sponge — soaks water in horizontally during the storm, then transfers it down through internal brickwork to bedroom ceilings.

3. Cracked or missing pot, broken cowl

If the pot is cracked or the cowl/flaunching has come off, water enters straight down the flue and shows internally as staining beside the chimney breast.

4. Cracked flaunching (the mortar bed around the pot)

Hairline cracks in the flaunching let water sit inside the top of the stack. Freeze-thaw widens the cracks every winter.

What to check from the ground

• Photograph the chimney with maximum zoom from the front, side and rear of the property
• Look for missing pots, leaning stacks, vegetation in joints, visible cracks
• Inside, photograph every patch of ceiling staining beside the chimney breast
• Check the loft for tide marks on rafters near the chimney

Don't try to access the stack yourself

Chimney work is the highest-risk part of any roof. We use scaffolding or proper tower access on every chimney job — never ladders directly to a stack. If you've got an active leak, our emergency roof team covers Hertfordshire and Essex 24/7 with same-day temporary weather-tight cover.

Permanent fixes

Depending on cause: re-lead the flashings, rake out and repoint the stack, replace cracked pots, re-cap the flaunching. Most full chimney refurbs sit at £900–£1,800 with scaffolding included, and last 25+ years.