Condensation is a building-physics question
A cold internal surface may increase the likelihood of high local relative humidity and condensation, depending on room temperature, moisture production and ventilation. Yet visible staining can also have other causes, including rain penetration, plumbing leaks, construction moisture and historic damage. A thermal image alone cannot distinguish these causes reliably.
What can ISO 13788 help with?
ISO 13788:2012 describes simplified methods for assessing critical internal surface humidity and interstitial condensation associated with water-vapour diffusion. These calculations can be helpful for an agreed design question, but their assumptions and scope matter. The standard's simplified interstitial assessment does not represent every process that affects moisture performance, such as liquid transport, capillarity and airflow through gaps.
In retrofit work, the existing substrate, exposure, ventilation, continuity of insulation, rain management and proposed materials may all matter. A simplified check should not automatically be treated as a full hygrothermal appraisal of a moisture-sensitive assembly.
What evidence helps a targeted investigation?
Record when and where the symptom occurs, internal and external conditions where possible, heating and ventilation use, visible condition, previous repairs and accessible construction information. A targeted site review may combine observation with appropriate temperature, humidity and moisture measurements and, where justified, further investigation or modelling. Findings should explain uncertainty and what remains unverified.
Do I need a moisture or retrofit review?
Tell Vertex about the wall type, affected room, symptom pattern and any planned EWI/IWI changes. We can discuss the scope of a practical investigation, junction review or design assessment and identify where additional specialist testing would be necessary.
Primary reference: ISO 13788:2012 — simplified internal surface humidity and interstitial condensation calculation methods