Why Does Rubble in A Cavity Wall Cause Problems?

Among many other things that a surveyor should be looking out for prior to any installation, Cavity Wall Insulation requires a clean cavity. Filling the cavity with insulation can cause damp if not cleaned correctly and this is often due to lumps of mortar (known in the trade as ‘snots’) lying at the foot of the cavity wall on the cavity ties.

As the wall was built it is possible that mortar fell in the cavity and came to rest on the ties. The problem is that rainwater hits the external skin and penetrates to the snot sitting on the tie. That is not a problem in an open cavity as the ventilation will dry any moisture penetration before it reaches the inner skin.

Filling the cavity with insulation will reduce the  ventilation. The rainwater will still hit the external skin and penetrate to the snot but now cannot be evaporated away and continues to penetrate to the inner skin across the insulation and emerges as a damp spot on the inner walls.

A good surveyor will check that your cavity wall is clean before filling it with insulation. Reputable insulation companies will do this for you as a matter of routine and give you an honest answer.

Unfortunately, we know that many cavity walls that contain rubble and mortar snots have been insulated. This has, or will more likely than not contribute to penetrative damp and further problems in time. In this situation, the cavity wall insulation will need to be removed fully.

Thermal imaging service is a useful tool to establish whether or not a cavity wall is being compromised by the presence of rubble and mortar snots. Although many cavity inspections clearly show an amount of rubble present in the base of the cavity and the insulation was

It is now apparent that hundreds of thousands of home owners across the UK will need remedial work that will consist of a full extraction of the Cavity Wall Insulation and could well mean a whole host of other repairs and replacements directly caused by the install, costing in excess of £10,000.

Mortgage lenders are also looking at properties which have had CWI installed and can devalue a property by as much as £30,000 if a valid CWI examination certificate is not available.

If you’ve got issues of any nature with your Cavity Wall Insulation that may be down to the installer not following proper guidelines as to the install, contact us for a free, no obligation review.

Contact Wall Cavity Claims today on free phone 0800-8-654321 or visit www.wallcavityclaims.co.uk

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