EcoTherm PIR insulation boards are rigid in nature and a closed cell material, meaning water absorption is minimised.
The Department for Communities and Local Government (CLG) recommend the use of closed cell insulation materials in their guidance document “Improving the Flood Performance of New Buildings” due to the materials' ability to recover from the effects of water immersion and to return to the expected level of thermal performance as soon as possible after the water has subsided:
"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)."
"Water will lower the insulation properties of some insulation materials. Floor insulation should be of the closed-cell type to minimise the impact of flood water...It is recommended that insulation be placed above the floor slab (and underneath the floor finish) rather than below would minimise the effect of flood water on the insulation properties and be more easily replaced, if needed."
The full CLG guidance document can be downloaded at http://www.planningportal.gov.uk/uploads/br/flood_performance.pdf