Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 27·6.4
Internal and external wall construction for ground moisture resistance
Internal and external walls must be constructed to resist moisture from the ground unless subject to ground water pressure, in which case different guidance applies.
An internal or external wall should meet the requirement to resist the passage of moisture from the ground if it is constructed as follows (unless it is subject to ground water pressure, in which case follow the guidance referred to in paragraph 6.6) –
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