The great danger then becomes interstitial condensation
, which can cause structural damage.
Internal surface temperature to avoid critical surface humidity and interstitial condensation
The extremely well-insulated envelopes are assembled to avoid interstitial condensation deposit in winter, not to eliminate problems with solar-driven vapor flow during warm weather.
Moisture tolerance in turn surpasses the one problem typically looked for: winter interstitial condensation.
ISO 13788, Hygrothermal performance of building components and building elements--Internal surface temperature to avoid critical surface humidity and interstitial condensation, calculation method.
A 95% closed cell insulation core prevents interstitial condensation
and other detrimental moisture effects.
Today highly sophisticated one- and two-dimensional full heat and moisture models are available that allow modeling vapor and liquid flow, that are transient in nature, that consider moisture sources such as wind-driven rain, rising damp, initial moisture, sorption and de-sorption, interstitial condensation and surface condensation.
Also the effect of air permeability on interstitial condensation deposit in roofs was tackled as was the discussion about attic ventilation.