Sections 5 and 7 of Approved Document F - Ventilation - 2010 edition - Guidance and amendments to it for new and existing dwellings.
Adrannau 5 a 7 o’r Ddogfen Gymeradwy F – Awyru – Argraffiad 2010 – Canllawiau a diwygiadau iddi ar gyfer anheddau newydd ac anheddau presennol.