Condensation Risk Calculator
Occupancy, moisture habits, extraction, ventilation, heating — scored into your home's winter condensation risk, with the specific fixes your answers point to.
Will my home get condensation and mould this winter? Risk is arithmetic: moisture produced (occupants, showers, cooking, indoor drying) versus moisture removed (extraction, background ventilation) versus surface temperatures (heating pattern, insulation). A household producing 10–15 litres of vapour daily in a sealed, intermittently heated home will condense it onto the coldest surfaces and grow mould — predictably. This calculator scores your setup and returns a risk level with the fixes your specific answers indicate, from £20 trickle vents to a £800–£1,500 PIV system.
Use the diagnostic
Answer the questions
Answer for how the home actually runs in winter. Your risk level and tailored recommendations appear instantly.
1. How many people live in the home?
2. Is laundry dried indoors on airers or radiators?
3. Bathroom extraction?
4. Kitchen extraction?
5. Background ventilation (trickle vents / regular airing)?
6. Winter heating pattern?
7. Any mould already appearing?
Related services and guides
Condensation Control
The service this tool points toward — diagnosis-first, independent qualified providers.
View the serviceVentilation Solutions (PIV)
The service this tool points toward — diagnosis-first, independent qualified providers.
View the serviceVentilation Guide: PIV, Extractors and Condensation Control
The in-depth guide behind this tool's logic.
Read the guideThe Complete Guide to Condensation and Mould
The in-depth guide behind this tool's logic.
Read the guideCondensation Risk Calculator FAQs
Simple honest arithmetic: points for moisture production (occupancy, drying), missing removal (extraction, background air) and cold surfaces (heating pattern), plus existing mould as ground truth. High scores mean the balance is set to condense.
In order of £-per-impact: stop indoor drying (free), open/fit trickle vents (£20–£50), make wet-room extraction real (£150–£400/room), steady the heating. Many homes drop a full risk tier on those alone.
Indirectly — the questions capture what matters (ventilation provision, heating, habits) whatever the fabric. Solid-walled and converted stock reaches dew point sooner, so treat a Moderate result in a period property as a nudge toward action.
No — scoring and recommendations run entirely in your browser.
Want a professional answer, not just an estimate?
Call today or book a survey — the right independent qualified specialist, matched to your property.