Cavity Wall Insulation, Flood Risk Homes, Defects Investigations.
The risky business of cavity wall insulation (CWI) in flood risk homes.
Flood risk locations: cavities in the external walls of homes in severe wind driven rain exposure locations and flood risk areas should generally not be insulated with standard cavity wall insulation (blown mineral wool, cellulose fibre, expanded polystyrene bead (EPS), urea formaldehyde foam, or open cell polyurethane (PUR) foam) as these materials can hold and transmit water across the cavity and into the masonry inner leaf of the cavity wall construction and lead to damp and black mould (mold) damage on the inner surfaces of decorative wall finishes, and consequently health related issues for the occupants.
Fig 1. Flood Risk Homes
Fig 2. Cavity Insulation Extraction & Clearance
According to Department for Environment, Food and Rural Affairs (DEFRA), Securing the future availability and affordability of home insurance in areas of flood risk, June 2013, around 5.8 million properties in the UK are estimated to be at some risk of flooding. Using DECC estimate, if 70% of these properties have already been insulated then it may be assumed that 4.1million properties in flood risk areas alone have already received inappropriate cavity wall insulation measures.
Following flooding, the above insulation materials should be removed from cavity walls, to eliminate the risk of effluent waste that could get trapped in the cavity.
The expense of repeat cavity insulation extraction will generally be too high to make cavity wall insulation a cost-effective energy efficiency solution in severe wind driven rain exposure locations and flood risk areas.
Fig 3. CWI Flood water damage to plaster
Fig 4. CWI Flood Damage to electrics
The key points to note are that:
In Great Britain as a whole, the majority of dwellings in flood risk areas have cavity walls
The majority (circa 70%) of these are already insulated
In the event of a flood, these properties will require:
cavity insulation extraction and
remedial works to overcome
- damage to electrics,
- damage to internal plaster finishes,
- damage to external render and masonry paint finishes,
- damage to external appearance caused by numerous unsightly drill holes in the external elevations of affected homes, and
- prolonged periods of heating and drying out and consequent alternative accommodation costs at hotels, etc.
Securing the future availability and affordability of home insurance in areas of flood risk, June 2013 https://consult.defra.gov.uk/flooding/floodinsurance/supporting_documents/20130626 FINAL Future of Flood Insurance consultation document.pdf
If you have had cavity wall insulation (CWI) carried out on your home which has caused damp, black mould, or health related issues, etc, and you require the assistance of a chartered building engineer please click here to contact us.