A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Addressing the geographical restrictions placed on full fill cavity wall insulation in the UK due to driving rain.
The two main home insurers in the UK, Zurich and the NHBC, impose restrictions on the use of full fill cavity wall insulation in very severely exposed areas. This is due to the perceived risk of water penetration. These restrictions limit the market for full fill insulation manufacturers. Existing literature and data on water penetration claims were insufficient to support anything other than conservative recommendations on construction. A liaison group was set up involving the insurers and other industry regulators, with a view to address these restrictions. This resulted in a programme of experimental testing. Empirical testing was undertaken to gauge water penetration as a function of cavity width, for both fully filled and empty cavities. In these tests, contrasting standards of workmanship were investigated. Computer models were developed to analyse fluid flow in a cavity at junctions, which are known problem areas. The Rainscreen Principle was investigated using pressure equalisation across outer leaves. All test walls with extremely bad standards of workmanship failed, apart from a 150mm fully filled wall in 'moderate' levels of exposure. The walls built to a typical standard exhibited no dampness problems, apart from a 50mm fully filled cavity in 'very severe' exposure. The performance of the empty cavity was on par with the fully filled walls. The pressure equalisation of the outer leaf could inhibit the passage of water across the cavity wall. Although the analysis of the data suggested that the restrictions could be relaxed, insulation manufacturers may have to take on a proportion of liability in order for the insurers to relax them. Future wall constructions will probably feature wider cavities that will have an effect on the water penetration properties. Further work is required in order to compile good quality data from which confident, impartial assertions can be made.
Addressing the geographical restrictions placed on full fill cavity wall insulation in the UK due to driving rain.
The two main home insurers in the UK, Zurich and the NHBC, impose restrictions on the use of full fill cavity wall insulation in very severely exposed areas. This is due to the perceived risk of water penetration. These restrictions limit the market for full fill insulation manufacturers. Existing literature and data on water penetration claims were insufficient to support anything other than conservative recommendations on construction. A liaison group was set up involving the insurers and other industry regulators, with a view to address these restrictions. This resulted in a programme of experimental testing. Empirical testing was undertaken to gauge water penetration as a function of cavity width, for both fully filled and empty cavities. In these tests, contrasting standards of workmanship were investigated. Computer models were developed to analyse fluid flow in a cavity at junctions, which are known problem areas. The Rainscreen Principle was investigated using pressure equalisation across outer leaves. All test walls with extremely bad standards of workmanship failed, apart from a 150mm fully filled wall in 'moderate' levels of exposure. The walls built to a typical standard exhibited no dampness problems, apart from a 50mm fully filled cavity in 'very severe' exposure. The performance of the empty cavity was on par with the fully filled walls. The pressure equalisation of the outer leaf could inhibit the passage of water across the cavity wall. Although the analysis of the data suggested that the restrictions could be relaxed, insulation manufacturers may have to take on a proportion of liability in order for the insurers to relax them. Future wall constructions will probably feature wider cavities that will have an effect on the water penetration properties. Further work is required in order to compile good quality data from which confident, impartial assertions can be made.
Addressing the geographical restrictions placed on full fill cavity wall insulation in the UK due to driving rain.
Batchelor, Peter Stanley (author)
2007-10-01
Masters thesis, University of London.
Theses
Electronic Resource
English
DDC:
690
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