Performance
C1
0.1 In the First Secretary of State's view the requirements of C1 will be met by making reasonable provisions to secure the health and safety of persons in and about the building, and by safeguarding them and buildings against adverse effects of
a. unsuitable material including vegetable matter, topsoil and pre-existing foundations;
b. contaminants on or in the ground covered, or to be covered, by the building and any land associated with the building; and
c. groundwater.
C2
0.2 In the First Secretary of State's view the requirements of C2 will be met if the floors, walls and roof are constructed to protect the building and secure the health and safety of persons in and about the building from harmful effects caused by:
a. moisture emanating from the ground or from groundwater;
b. precipitation and wind-driven spray;
c. interstitial and surface condensation; and
d. spillage of water from or associated with sanitary fittings and fixed appliances.
Introduction to Provisions
0.3 Sections 1, 2 and 3 of this document cover Requirement C1 and deal with site preparation and resistance to contaminants under the headings ‘Clearance or treatment of unsuitable material’, ‘Resistance to contaminants’ and ‘Subsoil drainage’. Building Regulations are made for the purposes of securing the health, safety, welfare and convenience of persons in and about buildings. This means that action may need to be taken to mitigate the effects of contaminants within the land associated with the building as well as protecting the building and persons in and about the building.
0.4 Hazards associated with the ground may include the effects of vegetable matter including tree roots. They may include health hazards associated with chemical and biological contaminants, and gas generation from biodegradation of organic matter. Hazards to the built environment can be physical, chemical or biological. Items such as underground storage tanks or foundations may create hazards to both health and the building. Physical hazards also include unstable fill or unsuitable hardcore containing sulphate.
0.5 In addition, the naturally occurring radioactive gas radon and gases produced by some soils and minerals can be a hazard.
0.6 Sections 4, 5 and 6 of this document cover Requirement C2 and deal with resistance to moisture under the headings ‘Floors’, ‘Walls’ and ‘Roofs’. Moisture can rise from the ground to damage floors and the base of walls on any site, although much more severe problems can arise in sites that are liable to flooding. Driving rain or wind-driven spray from the sea or other water bodies adjacent to the building can penetrate walls or roofs directly, or through cracks or joints between elements, and damage the structure or internal fittings or equipment. Surface condensation from the water vapour generated within the building can cause moulds to grow which pose a health hazard to occupants. Interstitial condensation may cause damage to the structure. Spills and leaks of water, in rooms where sanitary fittings or fixed appliances that use water are installed (e.g. bathrooms and kitchens), may cause damage to floor decking or other parts of the structure.
0.7 The diagrams in this Approved Document have been set out to show typical situations and relationships between adjacent elements of construction. Conventional notations and hatching have been used to identify different materials. However, the diagrams cannot show specific situations. It remains the responsibility of the designer and builder to ensure that the building work meets all relevant aspects of the Building Regulations.
Flood risk
0.8 There is a presumption in planning guidance7 that development should not take place in areas that are at risk of flooding. Flood resistance is not currently a requirement in Schedule 1 of the Building Regulations 2000. However, when local considerations necessitate building in flood prone areas the buildings can be constructed to mitigate some effects of flooding such as:
a. elevated groundwater levels or flow of subsoil water across the site - this can be alleviated by the provision of adequate sub-soil drainage (see Section 3);
b. sewer flooding due to backflow or surcharging of sewers or drains - this can be addressed through the use of non-return valves and anti-flooding devices (see Section 3, paragraph 3.6);
c. intrusion of groundwater through floors - this can be addressed through the use of water resistant construction (see Section 4, paragraphs 4.7 to 4.12);
d. entry of water into floor voids - provision to inspect and clear out sub-floor voids can be considered (see Section 4, paragraph 4.20).
Further information on flood resistant construction can be found in the publication Improving the flood performance of new buildings - Flood resilient construction.
Land affected by contaminants
0.9 The guidance given on resistance to contaminants in Section 2 is for the purposes of the Building Regulations and their associated requirements. Users of this document should be aware that there may be further provisions for dealing with contaminants contained in planning guidance or legislation made under the regime set out in Part IIA of the Environmental Protection Act 1990 which may be supplementary to the requirements of the Building Regulations. The Contaminated Land (England) Regulations 2000 make detailed provisions of a procedural nature to help give full effect to the Part IIA regime, and the statutory guidance provides a basis for enforcing authorities to apply the regime. Where contaminants are removed, treated or contained as part of the construction works, waste management law may apply. If waste is removed for off-site disposal, the 'Duty of Care' and/or special waste requirements will apply.
0.10 Redevelopment is often the most effective means of remediating land affected by contaminants. This process is subject to controls under the Town and Country Planning Acts, and local planning authorities follow the guidance in PPG 2312. Although environmental protection, planning and Building Regulations have different purposes their aims are similar. Consequently the processes for assessing the effects of pollutants and contaminants are similar. An investigation or assessment to determine the characteristics of a site can be further developed for Building Regulations purposes when the form and construction of the buildings are known. If appropriate data are gathered at the early stages it should not be necessary to completely re- evaluate a site for Building Regulations purposes.
Authorities that should be notified about contamination
0.11 Other regulatory authorities may have an interest in land affected by contamination. It may be necessary at any stage of the site investigation, risk assessment or remediation process to notify any unexpected events or change in outcomes to these regulatory authorities. The most likely situations are:
• The Environmental Health department of the district council should be informed if contaminants are found on a site where the presence of contamination has not been formally recognised through the planning process, if it is found that contaminants from the site are affecting other land or if contaminants are reaching the site from neighbouring land. Additional discussions may also be required if the contamination identified differs from that which has been previously discussed and agreed with the local planning authority (LPA) or Environmental Health department.
• As redevelopment is the most favoured means of dealing with land affected by contaminants, all land quality issues should be set out in documents in support of planning approval sent to the local planning authority. As designs are refined it may be necessary to inform the LPA of any impacts the design changes may have on the risk assessment and remediation strategy.
• The Environment Agency has a number of relevant duties at sites where contamination may be an issue; in particular these include specific duties relating to waste management and the protection of water quality and resources. Sites may be of concern to the Environment Agency where there is a potential impact on controlled waters, if the site is designated as a Special Site under Part IIA of the Environmental Protection Act 1991, where an authorisation may be required or specific hazards are found. The local Environment Agency office should be contacted to identify if there are any relevant issues.
• Some remedial measures may themselves require prior authorisation from the Environment Agency including abstraction licensing for groundwater treatment and waste management licensing for a number of activities involving contaminated soils.
• Working on contaminated land can be hazardous. The risks should be assessed to meet the requirements of the Construction (Design and Management) Regulations 1994. Working procedures should be in accordance with the Construction (Health, Safety and Welfare) Regulations 1996. It may be necessary to give notice to the Health and Safety Executive prior to work starting.
Specific guidance on the assessment of land affected by contaminants is set out in Appendix A.
Definitions
0.12 The following meanings apply to terms throughout this Approved Document:
Building and land associated with the building.
The building and all the land forming the site subject to building operations which includes land under the building and the land around it which may have an effect on the building or its users (see also paragraph 2.11).
Contaminant. Any substance13 which is or may become harmful to persons or buildings, including substances which are corrosive,explosive, flammable, radioactive or toxic.
Floor. Lower horizontal surface of any space in a building including finishes that are laid as part of the permanent construction.
Groundwater. Water in liquid form, either as a static water table or flowing through the ground.
Interstitial condensation. Deposition of liquid water from a vapour, occurring within or between the layers of the building envelope.
Moisture. Water in liquid, solid or gaseous form.
Precipitation. Moisture in any form falling from the atmosphere, usually as rain, sleet, snow or hail.
Roof. Any part of the external envelope of a building that is at an angle of less than 70° to the horizontal.
Spray. Water droplets driven by the wind from the surface of the sea or other bodies of water adjacent to buildings. Sea spray can be especially hazardous to materials because of its salt content.
Surface condensation. Deposition of liquid water from a vapour, occurring on visiblesurfaces within the building.
Vapour control layer. Material of construction, usually a membrane, that substantially reduces the water vapour transfer through any building in which it is incorporated.
Wall. Any opaque part of the external envelope of a building that is at an angle of 70° or more to the horizontal.
