Foam Cavity Wall Insulation Problems

Cavity wall insulation can cause damp.

Foam cavity wall insulation problems.

Until the recent fad for cavity wall insulation took hold the only times rainwater penetration was a problem was when the steel wall ties were dirty with mortar droppings and or built sloping downwards from outer leaf to inner leaf or the cavity itself was blocked at low level with mortar droppings or other debris. Incorrectly installed cavity wall insulation causes water to seep into a property s walls causing structural problems and damp patches that may also manifest into mould. If left unaddressed long term it can lead to all manner of problems include mould and mildew. When we went undercover to investigate the quality of insulation suitability inspections in 2011 our findings suggested that you can t always rely on assessors to carry out thorough inspections or warn of potential damp problems even those from big brands such as marks spencer npower and tesco.

A cavity wall is a double layered masonry wall on the exterior of a home. Spray foam installers missed some of the air leakage sites. Find out if your home s likely to be affected. Remove enough siding to jimmy the foam out probably 2 3 pieces per story per wall cavity.

In order of prevalence here are the problems i ve seen with explanations following the list. When retrofit cavity wall insulation is installed into a property that is located or built in a way that means it should not have the cavities filled or if the work is undertaken incorrectly the first and most obvious sign of a problem is almost always internal dampness. Spray foam isn t thick enough. However if moisture is getting into the cavity the insulation can hold that moisture against the metal wall ties and speeding up the rusting process.

Better yet remove it. Reinsulate with dense packed cellulose still my personal. Remove the foam to reinsulate. If your cavity is full of insulation and no moisture water or water vapour is getting into the cavity then you re probably going to be fine.

So here s the part that sucks for me what has to be done to fix the problem. Damp walls as one of the most well known problems with cavity wall insulation damp is an issue that no homeowner wants to see. So how is cavity wall tie failure linked to problems with cavity wall insulation. Yes you can use expanding foam insulation in cavity walls.

I ve seen a number of houses with problems even though they re insulated with spray foam. Spray foam insulation is a better insulator than mineral wool loft insulation as you need less of it to get the same insulating effect. In some cases the damp and mould resulting from cwi can cause health problems or exacerbate existing conditions particularly respiratory conditions.