News 26/01/09

Flooding – The Next Big Thing

In 2005/6 it was Part B and Part L. In 2009/10 we are all going to have to learn about Part C and how to build for flooding.

Due to the increased threat of flooding, the Government has agreed with recommendations in the Pitt Review: Learning Lessons from the 2007 Floods, which advises that flooding be dealt with in the next amendments to the Building Regulations, due in 2010.

Aside from planning, there are two key concepts involved in making buildings more ‘flood proof’. These are flood resistance and flood resilience. Resistance refers to constructions which, where possible, prevent floodwater entering a building and causing damage. Resilience refers to minimising the impact of flooding should water enter a building, to ensure structural integrity and allow drying and cleaning to be facilitated.

Central to the issue of resilience is the choice of products which react well in flooding situations, ideally, products that don’t react at all. Products which retain water, or which have their function compromised clearly need to be avoided.

Recent amends to the Building Regulations have ushered in an era of buildings that are intended to be more thermally efficient, and insulation is key to achieving this. However, some insulation products perform better than others under flooding situations. Certain products actually lose their integrity when soaked. This means that the building loses its thermal efficiency, as well as taking longer to dry.

In 2007, the Department for Communities and Local Government, along with DEFRA / Environment Agency published guidance which contains recommendations on products which deliver better performance based on laboratory research. In the case of floor and cavity wall insulation, the guidance advises the use of rigid closed cell materials, such as polyurethane insulation, which retain integrity and have very low moisture take-up. Technitherm® satisfies these criteria of flood resistance whilst simultaneously providing the best insulation and air leakage control in one application.

Other insulation types such as mineral wool fibre batts have high moisture take-up. These can remain wet for several months after exposure to flooding, slowing down the drying process. Blown-in insulation can slump and lose its integrity. When tested for water penetration, drying ability, integrity and the retention of pre-flood dimensions, both mineral fibre and blown-in expanded mica are categorised as delivering poor performance.

Over the next 18 months the construction industry will need to familiarise itself with the issue of flooding and will need to learn how to build to the next raft of Building Regulation amendments.

Acknowledgement:
John Roberts, Chief Executive of BRUFMA