Moisture, mould and why the wall assembly decides
Mould needs moisture, a food source and time. Remove any one and it cannot grow. A wall that stays dry and offers nothing to eat is the durable answer.
The three conditions
Mould requires water, organic food and a temperature range that buildings are always in. Design controls the first two.
Water arrives three ways: bulk water from rain, vapour diffusion through materials, and air transport through gaps. Air transport carries by far the most, which is why air sealing is a moisture strategy as much as an energy one.
Food, or the absence of it
Wood framing, paper-faced gypsum and organic insulations all feed mould once wet. Inorganic assemblies do not. That is a durability difference that shows up over decades rather than at handover.
Drying potential
No wall stays perfectly dry forever, so the useful question is whether it can dry when it gets wet, and in which direction. Vapour permeance, measured under ASTM E96, is the property that answers it.
What Guardian publishes
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Guardian states the panels are moisture and mould resistant and do not decay, expand or warp.
Source · Differentiation sheet
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EPS is totally absent of any nutritional value, so no fungi, mould or micro-organisms can grow within it.
Source · Products page, environment section
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Written by Data Subsystems, for Guardian Structural Technologies. Last updated .
Drafted from Guardian Structural product literature and published building-science sources. Awaiting Guardian technical review. Confirm any figure against the current product documents or ask us before you rely on it in a design.