BS 85500:2025

Flood resilient construction. Improving the flood performance of buildings. Guide. | Status: Current

1 Scope This British Standard gives guidance on how to improve the resilience of buildings through the consideration of resistance and recoverability to reduce the impacts of flooding from all sources, using suitable materials and construction details. Specifically, it provides guidance on:

1. a) assessing options for flood resilient measures, following a comprehensive flood hazard assessment and building survey; and
2. b) the design and specification of flood resilience for new buildings, extensions, conversions and retrofits.

The guidance covers the main types of building construction in the UK, for which experiential and other evidence is available. This British Standard is intended to be consistent with and complementary to the CIRIA Code of practice for property flood resilience [1] (see 4.2). It necessarily cannot cover all construction types and materials, and so additional guidance would need to be sought for any examples not covered in this British Standard. It is not applicable to:

1. 1) the detailed structural engineering;
2. 2) the site layout of buildings;
3. 3) the specification, fixing and deployment of flood resistance products, which are covered by other standards and documents, such as the BS 851188 series and Delivering benefits through evidence: Temporary and demountable flood protection guide [2];
4. 4) the design of watertight concrete, which is specified in BS EN 1992‑1‑1;
5. 5) amphibious or floating properties;
6. 6) properties on stilts; or
7. 7) avoidance measures outside the perimeter (footprint) of the building, such as local land raising above the predicted flood level.