Moisture from within the building should therefore be controlled and any points sealed where it may gain access into the roof space, such as holes around pipes and cables.
Felly dylid rheoli lleithder o'r tu mewn i'r adeilad a selio unrhyw fannau lle gall fynd i mewn i'r gofod to, megis tyllau o amgylch pibellau a cheblau.