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Climate, Environment, Buildings & Energy
Impacts of Improvements to Part L and Robust Details on Part C
(ref C1 71/6/1 BD 2414)

The project, ‘Impacts of Improvements to Part L and Robust Construction Details (RCD) on Part C’ was funded by the Department of Communities & Local Government and consisted of a fieldwork element, undertaken by Leeds Metropolitan University, and a modelling element carried out by the Bartlett School of Graduate Studies, University College London.

The fieldwork consisted of the analysis of design material and site surveys from 16 housing developments constructed to Part L 2002 and adopting the Robust Construction Detail route to compliance. The results of the analysis were used to enable condensation modelling that took into account not only the guidance of robust details but also the way in which construction details were actually designed and, perhaps more importantly, constructed. The modelling element of the project sought to identify the extent to which the ‘as built’ details give rise to a significantly increased condensation risk as compared to the relevant ‘standard’ robust construction details, as defined in the guidance.

In seeking to understand and place in perspective the results of the fieldwork it was important to understand the general issues raised by the specific observations and to avoid classifying the problems identified as “errors, defects or mistakes”. Like all general problems of quality management, the underlying issues were ones of system, not of individual or developer culpability.

The qualitative analysis of fieldwork led to a number of broad findings relating to design and construction raising questions regarding: the level of knowledge and understanding relating to robust details, the communication of detailed design requirements from designer to constructor, the placement and continuity of insulation, the understanding of thermal bridging issues, approaches to maintaining continuous primary air barriers and AVCLs, and general detailing around major structural elements. In addition to assessing ‘as built’ performance, the modelling phase of the project investigated the suitability of the relevant calculation methods used to assess the risk of surface and interstitial condensation and mould growth.

Condensation risk – impact of improvements to Part L and robust details on Part C. Final report: BD2414
Tadj Oreszczyn, Dejan Mumovic, Mike Davies and Ian Ridley: University College London.
Malcolm Bell, Melanie Smith, Dominic Miles-Shenton: Leeds Metropolitan University.

Smith, M., Bell, M. and Miles-Shenton, D. (2005)
Condensation Risk – impact of improvements to Part L and Robust Details on Part C. Interim Report Number 7 – Final Fieldwork Report. A Report to the ODPM Building Regulations Division under the Building Operational Performance Framework. Project Reference Number CI 71/6/1 (BD2414), Leeds Metropolitan University, Leeds, UK

Mumovic, D., Davies, M., Ridley, I., Oreszczyn, T., Bell, M., Smith, M. and Miles-Shenton, D. (2005)
An evaluation of hygrothermal performance of "standard" and "as built" construction details using steady-state and transient modelling. 9th International Building Performance Simulation Association (IBPSA) Conference. Montreal, Canada, The International Building Performance Simulation Association.