Proud member of the Federation of Damp
Sub Floor Ventilation and Condensation on King Charles Road, Surbiton KT5
A house on King Charles Road in Surbiton had mould and some old damp damage, flagged alongside a separate RICS survey. The survey found ventilation, not rising damp, was the main issue.
Project at a Glance
The Brief
The owners wanted to know if the house needed damp proofing.
The Survey
No widespread rising damp profile was found. Wall surfaces were generally dry or low, even where mould or old damage was visible, although a long dry spell meant winter conditions could differ.
Ventilation was a major factor. There were no trickle vents in the PVCu windows inspected, and no mechanical extract in the bathroom, kitchen or rear utility, which held laundry appliances, drying washing and wet footwear. Humidity dropped noticeably as doors and windows were opened. Outside, the air bricks were blocked by vegetation, debris and stored items.
The Solution
Ventilation first:
- Replace and clear the air bricks to restore sub floor airflow.
- Fit smart extract fans in the bathroom, kitchen and utility.
- External render, drainage and roofing defects from the RICS survey to be handled by others.
The Work
Four air bricks were replaced on 16 October 2026.
The Result
No internal damp proofing was recommended at this stage, saving the owners unnecessary work. See our page on damp proofing in Surbiton, or read about condensation.
Frequently Asked Questions
Do I need damp proofing if I have mould?
Not always. Mould often comes from condensation and poor ventilation, which damp proofing would not fix.
Why do air bricks matter?
They ventilate the space under suspended timber floors. Blocked air bricks leave the void damp.
Does drying washing indoors cause damp?
It releases a lot of moisture. Without extraction or ventilation, it adds to condensation.
Mould but no obvious damp?
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 Surbiton, KT5.
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.
