Signs you need this
- A damp patch spreading across a chimney breast in an upstairs bedroom
- Mortar dropping into the gutter or onto the path below the stack
- A pot leaning, or cement flaunching cracked right through
- Cement fillet at the roof line instead of lead, with a crack running along it
- White salt staining coming through the plaster near the fireplace
- A stack you can see daylight through from the neighbour's side
Why chimneys cause most of the damp we see
A stack is the most exposed masonry on the house. It gets wind driven rain on every face, it has no roof over it apart from a thin bed of cement, and on a Leeds terrace it often sits on a party wall so it is shared with a neighbour who may have different plans. Mortar in an exposed stack weathers far faster than mortar in a wall, and the freeze and thaw cycles we get through a West Yorkshire winter do the rest.
Inside the house the symptom is usually a damp patch on a bedroom chimney breast, sometimes with a brown tide mark and a bloom of white salt. People treat that as rising damp or condensation and put a dehumidifier in the room. It keeps coming back because the water is arriving at the top.
What we check on a stack
Every face of the brickwork, joint by joint. The flaunching, which is the sloped bed of mortar the pots sit in, and whether it throws water clear or holds it. The pots themselves, for cracks and for lean. Whether there is a damp proof course tray in the stack, which most Victorian stacks do not have. The four lead details around the base. And the flue, to see whether it is open, capped, or capped with no ventilation at all.
On shared stacks we look at both sides. Repointing your half and leaving the neighbour’s half open moves the problem sideways rather than solving it, and we will tell you that rather than take the job on false terms.
How we do leadwork
Lead is the only flashing material we use at a chimney. It gets dressed to the shape of the roof covering, tucked at least 25mm into a raked out bed joint, wedged and pointed. Step flashings follow the brick courses down the sides of the stack. Soakers sit between the slates underneath them, one per course.
Behind the stack there is a back gutter, and it is where poor work shows up fastest. It has to carry water from the slope above around both sides of the stack, which means a formed lead tray with proper upstands and a sensible fall. We see a lot of back gutters made from a flat sheet of lead and a bucket of mortar. Those leak within two or three winters.
Working on Leeds terraces and back to backs
Access is the practical constraint. A stack on a party wall between two through terraces usually needs a scaffold on one property and permission from both. On a back to back there is no rear elevation at all, so the scaffold goes on the street and Leeds City Council wants a highways licence for it. We handle the licence application and we speak to the neighbour ourselves if that helps.
How the work runs
- 1
Inspect from the scaffold
A stack cannot be judged from the ground or a drone alone. Once access is up we check every face, the pots, the flaunching, the DPC tray if there is one and all four lead details.
- 2
Decide repair or rebuild
If the brick faces are sound we rake out and repoint. If the top courses have blown or the stack leans, rebuilding from below the damage is the only lasting answer.
- 3
Get the leadwork right
Front apron, side soakers with step flashing, and a back gutter behind the stack. Each piece is sized and lapped so water is shed downhill at every junction.
- 4
Finish and test
New flaunching weathered to throw water clear of the brickwork, pots bedded and checked for plumb, then the whole stack photographed for your records.
What it typically costs
| Job | Typical range |
|---|---|
| Chimney repoint Rake out and repoint a single stack with new flaunching, scaffold charged separately | £650 to £1,500 |
| New flaunching and pot Recasting the top bed and resetting or replacing a pot and cowl | £300 to £700 |
| Rebuild above the roof line Taking the stack down to sound brickwork and rebuilding with a new DPC tray | £1,200 to £3,000 |
| Lead flashings to one stack Apron, soakers, step flashing and back gutter in code 4 and code 5 lead | £450 to £950 |
| Stack removal and make good Taking a redundant stack down below roof level, weathering in and ventilating the flue | £700 to £1,800 |
| New lead valley Between two slopes or between back additions, slates lifted and relaid either side | £600 to £1,400 |
Typical ranges for Leeds and the surrounding area , reviewed September 2026. Every quote is written and fixed before work starts.