With one in six homes in England at risk of flooding installing an insulation product that won’t slump or sag when wet is an important consideration when building new homes or carrying out refurbishment projects. 

The closed cell nature of PIR and PUR insulation means that water uptake is minimal giving a much faster drying out time, allowing building occupants to return to their homes much more quickly.

The use of closed cell insulation has long been advocated in flood risk areas and in 2009 a report published jointly by DEFRA, DCLG and the Environment Agency “Improving the flood performance of new buildings” cited rigid PUR foam as the best performing when installed into cavity walls. The report states “Cavity insulation should preferably incorporate rigid closed cell materials as these retain integrity and have low moisture take-up. Other common types, such as mineral fibre batts, are not generally recommended as they can remain wet several months after exposure to flood water which slows down the wall drying process. Blown-in insulation can slump due to excessive moisture uptake, and some types can retain high levels of moisture for long periods of time (under natural drying conditions).”

In 2015 BSI published a Standard BS 85500 “Flood resistant and resilient construction – Guide to improving the flood performance of buildings”.  Throughout the document the use of closed cell insulation products is recommended as the product of choice.

There have been a number of studies and trials into how to make properties more flood resilience and PIR products have been included in some of these.  You can read more about them here.

The Cumbria Flood Resilience Showcase project  uses a closed cell PIR product to minimise the impact of flood water alongside a range of flood resilient measures.

The BRE Flood Resilience Repair Home at the BRE in Watford also uses a variety of flood resilient measures including PUR injected into wall cavities, spray applied PUR, internal insulation lining boards and floor insulation.