Condensation behind cavity air brick

[jonnybegood]

All

Last year we got cavity wall insulation (bonded bead) installed.
No problems at first, but now on the inside of the bedroom wall (external wall) top corner I have started to notice condensation gathering.
I have read up on condensation and now open our trickle vents and dry 80% less of our clothes indoors and the condensation has greatly reduced.

However if I have a shower and leave the door open to the bedroom the condensation can be seen gathering in the same spot on the bedroom wall directly behind the cavity air brick.

I have 2 possible reasons for this:

1, the airbrick is keeping that part of the wall colder than the rest and attracting the condensation.

2, the insulation was not able to be installed behind the airbrick or has since install been blown away causing a cold spot on the wall.

What are my options, contact the installation company?

Would it be wise to block the air brick and then fill with extra insulation to warm the wall up in that area.

Just want the answers for the installation company if they try to shift the blame, any further advice / suggestions.

JBG

 

[Deluks]

If the airbrick has long been sealed up on the inside, then you should do the same on the outside too. Remove and brick it up. The cavity itself does not need a vent. Bit of squirty foam or chunk of polystyrene will make up for the small amount of missing insulation.

Also, keep the bathroom door shut during and after a shower and open a bathroom window.