Section 0 of the Approved Document offers an introduction to the provisions including the range of hazards, associated with the ground, that need to be taken into account, for example, vegetable matter and tree roots, chemical and biological contaminants, and gas generation from biodegradation of organic matter. Physical hazards include underground storage tanks, unwanted foundations, unstable ﬁll or unsuitable hardcore containing sulphates. Naturally occurring hazards include the radioactive gas radon and gases produced by other soils and minerals. To comply with Requirement C2 the range of moisture sources is listed, i.e. from the ground: driving rain or wind-driven spray; surface condensation from the water vapour generated within the building; and interstitial condensation. Spillage of water, from ﬁxed appliances, etc., also now needs to be considered.