Both the warm deck and warm deck inverted roof constructions, where the insulation is placed above the roof deck, are considered preferable. It is considered that more reliable forms of construction are available. However cold, level-deck roofs, should be avoided because interstitial condensation is likely and its effect on the structure and insulation can be severe and many instances of failure in such systems have been recorded. Clause 8.4.1 of BS 5250 lists various issues that should be considered in the design of roofs to reduce the possibility of excess condensation forming that might damage the building and endanger the health of the occupants. Section 8.4 of BS 5250: 2002 provides guidance on the control of condensation in the principal forms of roof construction. Very careful consideration of the issues is essential and the correct detailing will therefore be critical.Ĭonversions - in the case of conversions, as specified in regulation 4, the building as converted must be improved to as close to the requirement of that standard as is reasonably practicable, and in no case be worse than before the conversions (regulation 12, schedule 6). Higher winter temperatures combined with increased vapour pressures could result in more severe problems, particularly in roof spaces. The effects of climate change may exacerbate problems of condensation in buildings due to higher relative humidity. The guidance to this standard may not be fully appropriate for such buildings as their design is generally by specialists and often involves distinctive construction methods and materials required to produce buildings that are fit for purpose under the known conditions. There are buildings designed and constructed for specialist activities, controlled environments or factory processes that normally involve high humidity levels. For all of the above reasons the control of condensation is an important consideration in building design and construction. However excess condensation can damage the building fabric and contents and the dampness associated with mould growth can be a major cause of respiratory allergies.Ĭondensation can also affect thermal insulation materials as the measured thermal performance reduces with increased moisture content. ![]() Condensation need not always be a problem, for example it regularly occurs on the inner surface of the outer leaf of a cavity wall which receives very much more water from driving rain. ![]() The occurrence of condensation is governed by complex interrelationships between heating, ventilation, moisture production, building layout and properties of materials. list of standards and other publicationsĬondensation can occur in heated buildings when water vapour, usually produced by the occupants and their activities, condenses on exposed building surfaces (surface condensation) where it supports mould growth, or within building elements (interstitial condensation). ![]() ![]() 3.1 Site preparation – harmful and dangerous substancesģ.2 Site preparation – protection from radon gasģ.8 Private wastewater treatment systems – treatment plantsģ.9 Private wastewater treatment systems – infiltration systemsģ.17 Combustion appliances – safe operationģ.18 Combustion appliances – protection from combustion productsģ.19 Combustion appliances – relationship to combustible materialsģ.20 Combustion appliances – removal of products of combustionģ.21 Combustion appliances – air for combustionģ.22 Combustion appliances – air for coolingĪppendix B.
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