Approved Document C: Site preparation and resistance to contaminants and moisture
England-focused reference checklist
Editorial source review: 2026-10-17
https://saeedazarshab.com/articles/england-building-regulations/approved-document-c/

INDEPENDENT GUIDANCE — not project-specific legal/design advice or a compliance certificate. Check the official current requirements and applicable transition.

Part C addresses site preparation and resistance to contaminants and moisture. It connects ground conditions with floors, walls, roofs and the way water is managed. The useful first step is understanding the actual site and source of moisture, not choosing a damp-proof product before the cause has been investigated.

WHAT TO CHECK
[ ] Establish the available ground, drainage and site-history information, recording important gaps.
[ ] Arrange suitable investigations where contamination, ground gas, groundwater or unusual conditions may affect the proposal.
[ ] Coordinate moisture protection with the structural design, drainage and envelope junctions.
[ ] Agree which inspections are needed before membranes, cavities or below-ground work are hidden.
[ ] Document remedial decisions and relevant verification before proceeding to the next stage.

RECORDS TO KEEP
- Site investigation and contamination/moisture assessments
- Coordinated protection and drainage details
- Pre-cover inspections and verification of specified measures

WHEN TO GET SPECIALIST HELP
Seek appropriately competent ground, contamination or building-pathology advice when the cause or consequences are uncertain. A website cannot determine whether a site is safe for the proposed use.

SCOPE AND EDITION
Landing published 3 September 2013; confirm applicability to project and current source before specifying. Site contamination and moisture risks need site-specific assessment. Do not treat damp-proofing details as a substitute for ground investigation.

OFFICIAL SOURCES
GOV.UK — Approved Document C
https://www.gov.uk/government/publications/site-preparation-and-resistance-to-contaminates-and-moisture-approved-document-c

Contains public sector information licensed under the Open Government Licence v3.0, except where otherwise stated. Original practical summary by Saeed Azarshab.
https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/