Chimney Breast Damp After a Log Burner Install in Great Kingshill HP15
At a house on Spurlands End Road in Great Kingshill, the plaster on the chimney breast started breaking down after a log burner was fitted. The chimney had also suffered serious water ingress before it was repaired.
Project at a Glance
The Brief
The owners noticed the symptoms after the log burner went in and wanted to know if the two were linked.
The Survey
The inspection found significant plaster deterioration and a raised mid level moisture pattern on the chimney breast and side returns. The surveyor saw more than one likely cause: residual moisture and salts from the earlier water ingress, filler and lightweight repairs around the fireplace holding moisture, and limited ventilation in the enclosed chimney void after the install, which may cause trapped moisture and condensation around the flue liner.
Outside, the render by the chimney was hollow and debonded, and raised flower beds were restricting the sub floor air bricks.
The Solution
Advanced Damp proposed:
- Remove the affected finishes and treat the salts.
- Install a chemical DPC where suitable and apply a waterproof render system.
- Improve air bricks and have a HETAS registered installer check the flue ventilation.
The Work
The air brick and damp proofing work was carried out from 24 to 26 August 2026.
The Result
Each likely cause was addressed, with fire safety checks left to the right specialist. See our Buckinghamshire damp specialist page.
Frequently Asked Questions
Can a log burner cause damp on a chimney breast?
It can change how a chimney ventilates. If the void is sealed with no airflow, moisture can be trapped.
Why do salts matter on a chimney?
Old chimneys often hold salts from water ingress and combustion. They attract moisture and spoil plaster.
Who checks the flue ventilation?
A HETAS registered installer should check any change so it does not affect safety.
Damp on a chimney breast?
Our CSSW and CSRT trained surveyors find the real cause before recommending any work. Non-invasive survey with a clear written report. No obligation.
Survey carried out by Chris Baxter at Advanced Damp. Project completed in Great Kingshill, HP15.
Sam Fitzgerald is the founder of Advanced Damp and a working damp and structural waterproofing surveyor diagnosing and treating moisture problems in residential and commercial properties across London and the South East. He is FODCS certified (a Federation of Damp Certified Surveyor) and a member of the Federation of Damp. His hands-on work covers rising damp, penetrating damp, condensation, basement waterproofing to BS 8102, and thermal imaging surveys, and he has personally completed over 400 damp surveys across properties of every type and age. Everything he writes draws directly from jobs he has carried out. He does not write about treatments, products or causes he has not dealt with first-hand in the field.
