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Existing Context

CDM (GB) Knowledge Base


This section should identify all hazards associated with the existing site where the project is to be carried out.

The information will be obtained from the original health and safety file for the site, if there is one and / or from the line and level survey, searches into the past history of the site and investigation into such things as ground conditions and soil type commissioned by the client.

The aim of the health and safety audit is to identify all hazards present underground, at ground level, and within any existing structure. The audit must include drawings and documentation of all existing features in so far as this information can reasonably be made available. The possibility of hazards arising from the proximity of other installations such as airports should be considered, together with possible hazards associated with the prevailing conditions, for instance, extreme weather or proximity to the sea.


Ground Level



Include a brief description of current and previous use of any existing structures. Identify those to be retained and those to be demolished. Demolition and dismantling is considered a construction process and is audited in Section 2.0


Describe any part of the existing structure that is unstable and identify measures required to provide temporary or permanent stability.

Surface Loading

Define known floor and roof loading and specify any restrictions required e.g. for fragile areas.

Heights & Clearances

Describe all height restrictions and clearances of building and structures affected by the movements of the work-force, materials and machinery.

See Also

Fixtures and Finishes


Describe existing materials in terms of handling for weight and size to be encountered within the existing structure.

Identify any Asbestos, Lead or other dangerous substance within the structure.

Mechanical and Electrical Equipment

Describe existing Mechanical and Electrical installations affected by the project and identify known hazards.

Other Considerations

As a final check to this section, consider any other possible hazards within the existing site, either underground, at ground level or within any of the existing structures that could give rise to a hazardous situation. The effects of such things as prevailing weather conditions or proximity of the site to restricted areas should be considered in this context.