One of the UK’s largest zero carbon developments is benefitting from the high performance airtight membrane Wraptite-SA from A. Proctor Group. As part of a joint venture development, award winning housebuilder Hill, and Cambridge City Council have created a total of 208 energy efficient dwellings, comprising 104 affordable properties, and 104 for private sale.
The development at Clay Farm, Great Kneighton in Cambridge has been designed to achieve a BREEAM Excellent rating, requiring an airtightness level of less than 1. Wraptite-SA was specified by Kingspan Timber Solutions for the project to achieve the required standard, which would not have been possible with standard membrane construction.
Wraptite-SA, the only self-adhering vapour permeable air barrier certified by the BBA, was applied externally to the timber frame panels in continuous pieces. Traditional use of internal air barriers can be more complex and costly to install, due to the need to accommodate building services such as electrical, lighting, heating and drainage systems. The use of Wraptite-SA makes a significant contribution to a building’s thermal performance by preventing lateral air movement. It also provides high vapour permeability, which allows any water vapour to escape the wall construction efficiently thereby avoiding any interstitial condensation problems.
A. Proctor Group carried out on site air tests of trial units prior to commencement of the main project. Initial air tightness results after installation achieved a rating of 0.72, well within the target level of less than 1.
For any building to have an energy efficient, healthy, moisture free building envelope there is a clear need to manage the balance of Heat, Air and Moisture movement (HAMM) throughout the building’s life cycle from design, construction, completion and use.