Cavity Wall Insulation, Damp and bubbling paint

Slightly unusual this one, for me anyway.

We had cavity wall insulation fitted to our 1950's semi approx 1 year ago that was done via the local electricity company. The house was purchased 4 years ago and at the time of survey no damp was detected.

At the time of the installation I was concerned as I had read that cavity wall insulation should not be installed in properties that are prone to severe weather conditions. The house is very exposed with no properties in front or behind only hills and the sea (which is about 15 miles away!) and is situated in an area that the locals call the "rain band"! No problem they said!

Three months after installation, we found round damp patches halfway up the wall (no windows,pipes etc). The installation company examined and found voids. To cut the story short we now have had 4 refills/top ups due to voids. The internal plaster had blown in several places, white "salt" is everywhere up to 30cm from the floor and now the external masonary paint is bubbling off across the whole front of the property up to a metre high. Drilling a hole outside into the cavity reveal that the bricks are saturated. I've asked the company and the manufacturer to inspect the property again but I'm at a lost to see what they can do.

The options I can see are to remove the cavity wall insulation therefore stopping the damp from penetrating to the inside or to have the external rendering hacked off and redone to try and prevent the water penetrating from the outside. Any other idea's?

Many thanks in advance

Sounds like you have a severe problem in that the material in the cavity is allowing water to cross the cavity and is holding water.
Did you get a guarantee when you had the work done,? if so it should say words to the effect that it will not allow moisture to cross the cavity.
Most materials now will not let that happen unless it is blown in to dense.
In addition there should be an Agrement certificate detailing which parts of the country it can be installed and to what heights.
Don't mess about with the contractors go back to the electricity supplier and demand that it is removed and that the damage caused is made good at their expense.

Yes your first stop is the electricity board to see that they say. If no joy then you will need an independent expert to comment on the situation and possible cause.

From the information its difficult to give an exact diagnosis. There seems to be an issue with dampness bridging the cavity but whether this is moisture running down, penetrating laterally, coming up or even condensation related is going to be difficult to pinpoint unless there is something obvious.

As the walls were already rendered, then there should be very little moisture getting through in the first place - so could there have been defective render to start with and then the insulation has made the situation worse? This would be the first possible cause to investigate.

The mention of salts and blown paint at low level may be a breach of the DPC within the cavity, or moisture running down the inside of the wall and then being retained by the DPC

Whatever moisture is getting into the wall is being retained by the render, so the wall will remain damper for longer than a normal brick cavity wall.

Treatment will depend on what the cause is