BS 5250:2011+A1:2016 Code of practice for control of condensation in buildings

BS 5250:2011+A1:2016

Code of practice for control of condensation in buildings

Status : Current, Under review   Published : December 2011



What is this standard about?

The amendment to this standard follows rapid developments since 2011 in awareness and knowledge of the problems that moisture causes in buildings. It addresses some important issues ahead of a full revision of the standard in 2018.

Who is this standard for?

  • Architects
  • Surveyors
  • Building companies, insulation and other material manufacturers• Housing managers
  • Anyone involved in structural or thermal design, heating equipment, ventilation, mathematical calculations on buildings, condensation, damage prevention, surfaces or the retrofitting of existing buildings

Why should you use this standard?

It gives guidance on the risks associated with excessive humidity in buildings, notably mould growth and condensation, which can endanger the health and well-being of a building’s occupants and the integrity of the building fabric. It describes the principal sources of water vapour, its transportation and deposition, and provides guidance on how to manage those risks during the design, construction and operation.

The standard is relevant to buildings of all types, whatever their form, construction or level or type of occupancy, except buildings used for storage at sub-zero temperatures.

What’s changed since the last update?

Increased knowledge of the problems caused by moisture in buildings has led to the development of more sophisticated structural design and failure analysis techniques.  Concerns have also grown over moisture problems, generally due to climate change, as well as the drive to add insulation to walls, which disturbs the equilibrium of structures. Consequently, the main amendments are as follows:

  • A fuller discussion is provided of the more complex heat and moisture processes involved in the methodology of BS EN 15026, compared to the much simpler methods of BS EN ISO 13788 that are currently recommended.  (Section D.3)
  • Tables F.1, G.1 and H.1 are introduced to cover the recommended assessment methods for different types of floors, walls and roofs respectively
  • The most significant change comes in G.4.1.4. The addition of a vapour control layer (VCL) inside internal insulation (IWI) on solid walls was regarded as essential. However, it is now agreed that, in many cases, this may cause more harm than good. The revised guidance in G.4.1.4 essentially says 'be careful' and consider all the issues when installing IWI. Work to clarify these issues will continue for the full revision of BS 5250

Standard NumberBS 5250:2011+A1:2016
TitleCode of practice for control of condensation in buildings
StatusCurrent, Under review
Publication Date31 December 2011
Normative References(Required to achieve compliance to this standard)BS EN ISO 6946:2007, BS 8297:2017, BS 5720, BS EN ISO 13789, BS 6229, BS EN 1279, BS EN 490, BS EN ISO 13788, BS 8298, BS EN 14783, BS EN ISO 10211, BS 3533, BS 5925, BS 5534, BS 9250, BS 8104
Informative References(Provided for Information)BS EN 13141-7, BS 8103-2, BS EN 13141-4, BS EN 13141-2, BS 2972, BS EN 13141-10, PD 6697, BS EN 13141-8, BS EN 1996-2, BS 6576, BS EN 13141-9, BS 8103-3, BS EN ISO 13370, BS EN 1996-1-1, BS EN 13141-6, BS 8103-4, BS EN ISO 12572, BS 8103-1, BS EN 12524, BS EN 13859-2, BS 8204, BS 8102, BS EN 13141-3:2017, BS EN 15026, BS EN 13141-1:2019
ReplacesBS 5250:2002
Amended ByAmendment, July 2016
Draft Superseded By16/30339578 DC
DescriptorsStructural design, Ventilation, Thermal design of buildings, Damage prevention, Surfaces, Buildings, Design, Heating equipment, Mathematical calculations, Condensation
ISBN978 0 580 93804 7
File Size2.039 MB

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