'Leaking' Cavity Wall Insulation

[johnM20]

My house was built in 1983 by a well known national house-builder. The walls had polystyrene bead insulation put in at the time of the build but these beads are not bonded together in any way. When the cavity was exposed when new d/g windows were fitted it resulted in mountains of beads running out despite frantic efforts to stem the flow. Beads also escape when doing something simple like putting a pipe through the wall.

I recently had to remove a window board in the first floor bathroom during renovation work. This exposed the cavity again and I was able to see that the level of the beads was now below the window level. Whether there had never been a complete fill of the cavity, whether the beads have settled over the last 30 years or whether this showed just how much has been lost over the years we will never know for sure although I suspect the first reason. The level of the beads, as far as I could see into the cavity, was fairly horizontal which makes me suspect that probably half of the first floor walls are now un-insulated. If it was cost cutting or poor workmanship I won't be able to claim under the 10 year guarantee now.

I have spoken to one insulation firm who weren't interested in a 'top-up' of insulation and another said they would have to take out all the existing beads as any new material may not be compatible with the old, (I find that a bit difficult to accept). Both said that the job wouldn't qualify for the government grant scheme. If I have to pay for it myself is it actually going to be more cost effective to just live with it as it is and pay slightly higher gas bills? All major jobs where the cavity may be exposed have now been completed so future bead loss probably won't be a problem. All comments and suggestions welcome.

[spats]

I cant help but I am also in a similar situation.

Our house was filled with the little ball type cavity insulation decades ago. Also we doubt any bonding or glue was used so over the years the balls have found their way out. So much so when the upstairs windows were done we lost none so the level must be quite low!

Asking a few companies we were told the same thing. New stuff "wouldn't be compatible" with the old stuff and they would need to drain what was there at quite considerable cost!

I friend told me to just tell them there wasn't any in there to our knowledge but I bet they would drill holes and check first.

Does anyone actually know why the old and new stuff wouldn't work together?