§ Mr. Latham
asked the Secretary of State for the Environment whether he will make a statement on research or testing work carried out by (a) the Building Research Establishment and (b) the British Board of Agrément regarding the prevention of damp penetration on severely exposed sites through cavity filled walls, indicating the results of such research and tests.
§ Sir George Young
The results of the recent Building Research Establishment investigation of the resistance to 209W rain penetration of cavity filled walls are contained in "Building and Environment" in 1982. The results of BRE site studies of the practical implications of built-in cavity fills are given in the architects Journal of 2 November 1983. General guidance is provided in BRE Digest No. 236 and more recently in a publication "Cavity insulation of masonry walls—dampness risks and how to minimise them". This was prepared jointly by the British Board of Agrement, Building Research Establishment, National Federation of Building Trades Employers (now the Building Employers Confederation) and the National Housebuilding Council (England and Wales). I am arranging for copies of the relevant reports to be available in the Library.
The Meteorological Office under contract to BRE has developed an improved method for assessing exposure conditions for buildings. This formed the basis of a recently published BS draft for development DD93 "Methods for assessing exposure to wind-driven rain".
The BBA (then the Agrément Board) issued its first Agrément Certificate for a cavity fill material suitable for use on severely exposed sites in 1969. In issuing that certificate, account was taken of the evidence available from the use of cavity fill insulation in the United Kingdom installed during the previous ten years. The BBA has also developed a water penetration test in which a masonry wall with its cavity filled with insulation is subject to conditions which result in water penetrating one leaf of the wall and flowing down one face of the insulation at a rate greater than can occur from driving rain. All the cavity wall insulation products for filling cavities which are currently the subject of an agrément certificate, allowing their use in severe exposure, have passed this test. The test specification has been made available to BSI and other bodies and tests in accordance with it are now being carried out by a number of laboratories.