Moisture, mold and why the wall assembly decides
Mold 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
Mold 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, vapor 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 mold 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. Vapor 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 mold 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, mold or micro-organisms can grow within it.
Source · Products page, environment section
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Published by Guardian Structural Technologies. Last updated .
Drafted from our product literature and published building-science sources. Awaiting our technical review. Confirm any figure against the current product documents or ask us before you rely on it in a design.