06/03/2022
I took this post below off Linkedin, I am seeing more and more of this type of 'Roof Insulation', it's very controversial within the Industry and I've also seen plenty of dodgy adverts on Facebook claiming Grants when it's just a sales ploy, boost the price and discount with a 'Grant'.
I understand it can create problems if you sell your property, the Surveyors report it in their report and some mortgage Companies may refuse a mortgage.
Sprayed Foam Insulation- Is this good or bad for your loft?
Sprayed Foam Insulation has been available for the past 30 years and has been advertised by the manufacturers not only to improve the insulation of the loft but also to repair old roofs suffering from failures such as nail fatigue and water pe*******on as the foam binds together the covering, the battens and rafters.
There are two types.
Open-cell foam – this type is very light, easy to tear and allows water vapour to pass through into its structure so requires a vapour barrier.
Closed-cell foam – this is much denser and more expensive than open-cell insulation and acts as a vapour barrier providing a higher level of thermal efficiency.
The Problem:
Whilst there is little reliable scientific evidence, in practice, many mortgage companies refuse to lend on properties where sprayed foam has been installed making it hard for the homeowner to sell and this will undoubtedly affect property values.
The main concerns among surveyors are that, despite the claims from the manufacturers, sprayed foam can cause interstitial condensation on the cold side of the insulation resulting in decay in the tiling, battens or the rafters themselves, often not visible from an internal inspection.
The quality of the application is crucial. The rafters should not be totally encased by the foam and if the insulation is efficient at forming an air barrier then it follows that any water vapour finding its way into the roof void needs to be ventilated to avoid condensation particularly if closed-cell insulation is used.
Where foam is applied to the roof slopes a warm roof is created which means any insulation at ceiling height must be removed.
Depending on the underlay type, a vapour-control layer may still be needed on the warm side of the insulation. Gaps in the insulation, if poorly applied, could then permit air leakage and consequent condensation on the underside of the roof covering.
Removal of the foam is difficult, very labour intensive. and unlike a conventional roof covering repair, the battens and rafters often have to be replaced as well.
Other concerns relate to off-gasses, poor installation, use of the wrong cell foam and PVC cabling coming into contact with the foam.
In conclusion
Concerns over spray foam might not be fully supported by an examination of the evidence, and failures could be due to other causes rather than the foam itself, for example, poor ventilation, high humidity, or the presumption that a poor roof covering can be made sound by a sprayed coating. Even a conventionally insulated roof void could suffer from a lack of ventilation, high levels of insulation and poor vapour control causing rot to the roof timbers so it would be wrong to criticise sprayed foam simply based on perceived risk. However, until mortgage companies change their attitude my advice is to view the treatment with caution and make sure your clients are made aware of the pros and cons.
