What is BS 5250:2021 about?
Moisture in buildings is a significant cause of building failure and of building-related health issues. BS 5250:2021 supplies recommendations on how to manage moisture in buildings. The standard was revised to take into account the interaction of multiple building elements and the changing ways in which buildings are being constructed and used.
Who is BS 5250:2021 for?
- Architects
- Surveyors
- Building contractors
- Insulation and other material manufacturers
- Housing managers
- Environmental/sustainability consultants
- All those involved in: structural design, thermal design, heating equipment, ventilation, mathematical calculations on buildings, condensation, damage prevention, design, surfaces, energy performance/efficiency, building protection, the retrofitting of existing buildings, the health/wellbeing building occupants, moisture design, damp, facilities management
Why should you use BS 5250:2021
This British Standard gives recommendations for the management of moisture in buildings using an integrated and pragmatic approach. This includes the management of moisture risk from interstitial and surface condensation, from too high or too low internal relative humidity, and from rain penetration or high levels of ground water.
The standard covers all states of water as gas, liquid and solid, and the interactions between these states. It describes the principal sources of moisture in buildings, its transportation and deposition and provides guidance on how to manage those risks during the assessment, design, construction and operation of buildings.
This revision reflects our growing understanding of moisture risk in buildings and the fact that even though some risks are decreasing (mainly because of central heating) others are increasing because of increased airtightness and insulation, fuel poverty, overcrowding and changing use of buildings.
BS 5250:2021 is relevant to buildings of all types, whatever their form, construction and occupancy, both new and existing, and both domestic and non-domestic, although it does not cover buildings used for storage at sub-zero temperatures.
NOTE: This British Standard does not cover measures specifically to deal with flooding and escape of water. These are dealt with in BS 85500.
What’s new about BS 5250:2021?
This is a full revision of BS 5250:2011 since when knowledge of the problems caused by moisture in buildings has advanced rapidly. As a result, BS 5250:2021 takes a new, whole-building approach that considers the interaction of multiple elements in a joined-up way and is therefore more closely related to real world moisture problems and risks.
This revision also reflects the new challenges that arise from the changing ways in which buildings are being constructed, retrofitted and lived in, particularly regarding efforts to create low-energy buildings with increasing amounts of insulation and airtightness.