Calculate surface relative humidity and accurately predict mould growth risk in your home. Understand why mould forms and how to prevent it effectively.
This tool helps understand mould risk, but existing mould needs professional remediation. Our surveyors identify the root causes of mould growth.
Enter your conditions to calculate surface relative humidity and mould growth risk.
Learn why mould forms and how surface conditions determine growth risk.
Cold surfaces create local high humidity conditions, even when room air seems dry. This "micro-climate" is what mould spores respond to.
The greater the difference between air and surface temperature, the higher the surface RH. Cold bridges and insulation gaps create perfect mould conditions.
Mould can begin growing within 24–48 hours at >90% surface RH. At 75–90%, growth may take weeks. Below 75%, mould spores remain dormant.
While this calculator helps understand mould risk, persistent mould problems need professional diagnosis. Mould is often a symptom of underlying damp issues that require specific treatments.
Identify cold spots & thermal bridges
Precise moisture level measurements
Actionable solutions for your home
Our surveys accurately diagnose mould causes and provide specific prevention strategies for your property.
Our experienced damp specialists provide comprehensive surveys to accurately diagnose moisture issues. Get a detailed report with actionable solutions tailored to your property.