England · National documents
Site preparation and resistance to contaminants and moisture: Approved Document C
Covers site preparation, contaminants, sub-soil drainage and resistance to moisture in floors, walls and roofs.
AI-generated summaries of the linked official sources; not editorially reviewed. Sources and limits
Where this document applies
England: building work within the scope of the applicable regulations and edition.
Site preparation and resistance to contaminants and moisture: Approved Document C (official source, opens in a new tab) · Documents; Details
Scope of this source
Covers site preparation, contaminants, sub-soil drainage and resistance to moisture in floors, walls and roofs.
Read the official source (official source, opens in a new tab) · Details; Documents and the applicability provisions in each edition
Official document and edition
Approved Document C: site preparation and resistance to contaminants and moisture. The official file contains the detailed scope, diagrams and qualifications needed to interpret this guidance.
Read the official source (official source, opens in a new tab) · PDF supplied under Documents on the publication page
Limits and checks
- Building regulations approval and planning permission are separate. This document is guidance on compliance, not the regulations themselves.
- Check the edition, commencement date and transitional provisions against the building work. A publication date alone does not establish which requirements apply.
Read alongside this document
- Planning practice guidanceHousing: optional technical standardsExplains optional housing standards for accessibility, water efficiency and internal space, including the role of local planning policies.
- Technical standardTechnical housing standards – nationally described space standardSets out the nationally described internal space standard for new dwellings, including floor areas, storage and bedroom dimensions.
Put the national source in your local context
Start with the exact refusal reason. Note the policy and paragraph it cites, then check your authority’s policy summary and the facts discussed in relevant appeal decisions. Each appeal turns on its own facts and does not predict another outcome.