Do not be tempted to block the ventilation to reduce drafts as this can lead to a build up of moisture, creating the ideal conditions for wet and dry rots to develop.
Peidiwch â chael eich temtio i flocio mannau awyru er mwyn lleihau drafftiau oherwydd gall hyn wneud i leithder gronni, gan greu'r amodau delfrydol i bydredd gwlyb a sych ddatblygu.