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The purpose of this paper is based on recent research at Oxford Brookes University which explored how metal building envelopes can provide high levels of air‐tightness.

An intensive research programme tested many of the foremost cladding systems used in the UK. Over 500 individual tests have produced reliable data on the performance of different joint types. This paper summarises that data and identifies key design issues and solutions.

The research has demonstrated that metal building envelopes can provide very high levels of air‐tightness providing that they are properly engineered and assembled. It also presents compelling evidence, based on whole building thermal dynamic simulations using the test data, that further increases in air‐tightness are achievable; far more energy can be saved by doing this than by increasing thermal insulation even further.

The testing programme concentrated on steel cladding systems, both built‐up and composite panels, with technical assessment of different joints assemblies using a dedicated purpose‐built air‐tightness test rig.

As this research and other studies have shown that far more energy can be saved by achieving high levels of air‐tightness than by increasing thermal insulation even further, it suggests that a major change in regulatory strategy is now due.

The value of the paper lies in the originality of the testing programme and method. Although BSRIA has been testing whole completed buildings for air‐tightness using large mobile fan units pressurising the building to 50 Pa, it is the first time that a variety of cladding systems have been tested for air‐tightness on a large scale and in a laboratory environment; BRE carried out air‐tightness testing on few steel cladding systems on a smaller scale.

This paper is based on a research project sponsored by the DTI, with contributions from construction industry partners. The principal objective of the research was to generate data (based on a sample of new‐build housing schemes) about the levels of compliance with Building Regulations and standards typically achieved in England and Wales.

The field research consisted of a triangulation of three research methods. A series of observations of 11 speculative housing projects (in Oxfordshire and Gloucestershire) during construction. A questionnaire survey of occupants of recently completed speculatively built houses. A total of 200 questionnaires were distributed in eight housing developments completed 9‐15 months previously. Semi‐structured interviews with six building control inspectors, both local authority and approved inspectors.

The general conclusions are that levels of compliance were not always sufficient, though there was no evidence of systematic and purposeful non‐compliance with building regulations. Faults were largely due to lack of skills and knowledge of the required standards on the part of the operatives, and shortcomings in site management and toleration of sub‐standard workmanship.

The surveys were limited to projects by national or regional scale housing developers on mainly medium‐large size house developments that included semi‐detached, detached and townhouses.

The recommendations point to the need for more initial and continuing training of tradesmen, both in trade skills and knowledge of the provisions of building regulations, and more rigorous site management procedures adopted, particularly when pressure for completion is at its greatest.

The value of the paper is linked to the originality of the research; prior to it, reliable evidence of the scale and extent of non‐compliance with Building Regulations in the UK was not recorded in any publicly available source.