Improved Economy in the Design of Dwelling Basement Walls

Project partners: DTI, DTLR, Kingston University, Basement Development Group, NHBC, Autoclaved Aerated Concrete Products Association, Brick Development Association Ltd., British Cement Association.

Basements enable the better utilisation of land by increasing the useable living space per plot, thereby optimising the use of scarce building land and helping to reduce the environmental impact of new housing. The increasing need to use brownfield and other "difficult" sites often results in the need for deep excavation and contributes to the cost-effectiveness of providing a basement. Basements offer high standards of thermal performance, hence addressing the key environmental need to reduce the consumption of carbon based energy. The proposed amendments to Part L of the Building Regulations will increase the relevance of their inherently good energy efficiency and low carbon dioxide emissions performance.

Basements and semi basements are an important means of providing improved amenity in new dwellings. Using unreinforced brick or block masonry would assist in this major improvement to the provision of living amenity in the UK. Neither BS 5628:Part 1 Use of Masonry nor the Basements for Dwellings Approved Document cover this due to the lack of a suitable design method. Eurocode 6 contains a simple approach which results in over-safe and uncompetitive solutions for UK use.

Unreinforced masonry is much more attractive in this situation than reinforced masonry because it has better client value and is simpler, easier, cheaper and quicker to build. An earlier Project - Plain Masonry Basement Walls has developed a more economical basis for the design of unreinforced basement walls.

The outcome of the project will be an updated "Basements for Dwellings" Approved Document to the Building Regulations (first published in 1997) incorporating information dealing with plain masonry walls for basements.
This will facilitate more widespread user take-up of domestic basements and semi-basements as improved amenity through:

  • Reduction in the overall cost of building basements for dwellings.
  • Use of simplified basement construction methods.
  • Improvement in the ratio of construction cost to dwelling useable floor area.
  • Improvement in the ratio of useable floor area to site area


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