Bead insulation between plasterboard and hollow block

Citroen2cv

Does anybody know of a company that can pump bead insulation into the small cavity behind plasterboard, that is fixed to a hollow block wall with adhesive dabs? (similar to the pic below):


From having drilled a few holes, and having taking plasterboard off elsewhere in the house, the dabs are roughly 30mm thick, so that is 30mm of a cavity. I cant seem to find any company advertising this, or know even if it is an acceptable method of insulation.
Any help appreciated.

Poor Uncle Tom

Any dab fixing I've seen has been tight to the blockowrk, how would you even get an even finish trying to maintain a 30mm gap using dabs?

A small bit more detail please, what's on the other side of the hollowcore block?

Citroen2cv

well I have taken plasterboard off on external walls in 2 rooms in the house, and there was a fairly consistent thickness to the adhesive dabs, and still a fairly good plumb finish to the plasterboard. The adhesive dabs were not done in a continuous dab along the edge of each plasterboard sheet, so if i could use pumped beads, then the beads would go in easily without too many holes needing to be drilled.

Citroen2cv

Poor Uncle Tom wrote: »

A small bit more detail please, what's on the other side of the hollowcore block?

A pebbledash render.

murphaph

The dabs form a huge cold bridge though, so what's the point when the heat will just travel through the dabs to the wall. And that's assuming the beads successfully fill the remaining space.

Water John

I think the pumping needs a min of 50mm. It's difficult to fill, for example a twin block cavity that was partially filled with aeroboard first day.

BryanF

IMO Boards would show up cracks from the dabs with pressure from beads

MicktheMan

Citroen2cv wrote: »

or know even if it is an acceptable method of insulation.

A waste of time and might even promote mould growth on the dabs if the conditions are right.

Johnnyhpipe

I would imagine you'd gain zero noticeable difference (apart from the difference you'll convince yourself exists in order to justify the money you've just wasted!).

It is not an 'acceptable' detail to me. Perhaps consider external insulation.

Southern Comfort

I had an identical problem recently..... plasterboard dot and dabbed onto a cavity block external wall. I decided to remove the plasterboard and the dot and dab.
The dot and dab was all over the place on the wall... a lot here, a little there, etc. Removing it with a small kango was a dirty job but very worthwhile. I gained about 25mm overall and I was able to replace it with Ballytherm 72.5mm insulated plasterboards. The difference on cold nights is unbelievable.

Murphaph is correct when he says that you dot and dab would mean a lot of cold bridges. The same would be true if you tried to pump foam into your cavity blocks. (A few years ago, I came across a company who claimed they could insulate cavity block houses that way.....!)