Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 26·5.18
Drainage and ground level requirements beneath slab
Ground below slab must be entirely above the highest level of adjoining ground, or drainage must be installed on the upslope side of the building on sloping sites to prevent water collection.
To prevent water collecting on the ground below slab, either the top of the ground below slab should be entirely above the highest level of the adjoining ground or, on sloping sites, drainage should be installed on the outside of the upslope side of the building (see Diagram 5.3).
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