"Winter is moisture-proof, summer is moisture-permeable." It is a special airtight sheet that maintains airtightness throughout the year while allowing permeability to change according to the humidity conditions within the wall.
■Winter moisture-proofing, summer moisture-permeability
While ensuring airtightness (not allowing air to pass through), in winter it functions like a regular moisture-proofing airtight sheet, preventing moisture from passing through, and in summer, when the interior of the wall becomes hot and humid, potentially leading to mold and condensation, it allows moisture to pass through, maintaining a good condition inside the wall throughout the year.
In summer, moisture tends to move towards the interior due to temperature gradients, but if a regular moisture-proofing airtight sheet (PE sheet) is installed, the humidity between the insulation and the PE sheet can become extremely high. Particularly, immediately after construction, the structural elements and moisture released from the foundation concrete are significant, leading to increased humidity inside the wall and further raising the risk.