1.1The preparation of the site will depend on the findings of the site investigation. The site investigation is relevant to Sections 1, 2 and 3 of this Approved Document and also to the requirements of Approved Document A with respect to foundations. The site investigation should consist of a number of well-defined stages:
1.2The extent and level of investigation need to be tailored to the type of development and the previous use of land. Typically the site investigation should include susceptibility to groundwater levels and flow, underlying geology, and ground and hydro-geological properties. A geotechnical site investigation should identify physical hazards for site development, determine an appropriate design and provide soil parameters for design and construction. British Standard BS 5930:199914 provides comprehensive guidance on site investigations. Guidance on site investigation for low-rise buildings is given in six BRE Digests covering procurement15, desk studies16, the walk- over survey17, trial pits18, soil description19 and direct investigation20. Reference should also be made to BS 8103-1:199521.
1.3Where the site is potentially affected by contaminants, a combined geotechnical and geo-environmental investigation should be considered. Guidance on assessing and remediating sites affected by contaminants is given in Section 2: Resistance to contaminants.
1.4 Vegetable matter such as turf and roots should be removed from the ground to be covered by the building at least to a depth to prevent later growth. The effects of roots close to the building also need to be assessed. Consideration should be given to whether this provision need apply to a building used wholly for:
- A. storing goods, provided that any persons who are habitually employed in the building are engaged only in taking in, caring for or taking out the goods; or
- B. a purpose such that the provision would not serve to increase protection to the health or safety of any persons habitually employed in the building.
- 1 Distribution of shrinkable clays and principal sulphate:sulphide bearing strata in England and Wales
- 2 Example of a conceptual model for a site showing sourceâpathwayâ receptor
- 3 Subsoil drain cut during excavation
- 4 Ground supported floor - construction- see par 4.7
- Diagram 5 Suspended timber floor - construction - see par 4.14 a (i)
- Diagram 6 Suspended floor - preventing water collection-see par4.14a
- Diagram 7 Typical floors exposed from below
- Diagram 8 Damp proof courses- see par 5.5 (b)
- Diagram 9 Protecting inner leaf - see par 5.5c
- Diagram 10 Protection of wall head from precipitation - see par 5.9(c)
- Diagram 11 Insulated external walls examples -see paragraphs 5.10, 5.13 and 5.17
- 12 UK zones for exposure to driving rain
- Diagram 13 Window reveals for use in areas of severe or very severe exposure to driving rain - see paragraph 5.32
- Diagram 14 Accessible threshold for use in exposed areas- see par 5.33