This paper presents the results and key messages that have been obtained from Phase 1 of a participatory action research project that was undertaken with 5 developers to investigate the practical design and construction issues that arise in making improvements to the airtightness of speculatively built mainstream housing. Two construction types were represented in the project, masonry cavity and light steel frame. Phase 1 of the project sought to assess in detail the design, construction and air permeability of 25 dwellings that were constructed to conform to the requirements of Approved Document Part L1 2002. While the total number of dwellings reported here is small, the results suggest that there is not a consistent approach to the way in which developers present information on air leakage to those on site, a mixture of approaches are utilised on site to achieve the same specification and there appears to be a lack of foresight in the detailed design stage, resulting in specifications that are practically very difficult to achieve. Despite this, the air permeability results suggest that dwellings constructed with a wet/mechanically plastered internal finish, can default to a reasonable standard of airtightness by UK standards, without much additional attention being given to airtightness
