Cavity Wall Question - Is it a bad job

27 Jan 2008
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United Kingdom
We recently had cavity wall insulation fitted, and I think they may have made a mistake...but Id like to get some further advice before taking it up with them;

We have four vents around the front and side of our property, which are simple air vents. I was under the impression that when cavity wall insulation is done, sleeves of some kind should be fit to the inside of the vents so that they are not blocked.

As it currently stands, our vents are totally blocked by the substance which was pumped into our walls.

We have a very reputable firm do the work, from what I understand they are pretty much the UK experts on cavity wall.... so I'd be shocked if the have made such a fundamental error. Maybe the modern type of insulation material does not require this sleeve to be fit inside vents?

Many thanks if anyone can clue me up on this.

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it depends on what the purpose of the vents were. the only one's i'm familiar with are those required for wooden ground floors. these need to remain open to stop rotting of the timber joists which will happen if the vents are blocked.

check the ht of the vents in relation to the floor level.

if they are simply vents in the cavity then by virtue that the cavity is now full of insulation they are effectively redundant. their original purpose being to remove any moisture in the event that water got into the cavity due to deterioration in the buildings outer fabric or caused by condensation at lintels in the outer leaf of brickwork.
If these vents ventilate the inside rooms, then yes they should be lined and remain as vents. Being blocked up has removed the ventilation and increased the risk of condensation and mould problems inside the property.

In fact, if one of these vents is to a room with a gas fire or certain type of boiler, then its a big mistake

I'd like to hear their explanation

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