Not quite diy, but does anyone have a view (positive or negative) on
modern cavity wall insulation with foam or granules.

I had a previous house done with insulation foam in the 1970s and I
had no problems at all - apart from giving myself a problem later when
trying to drop a TV cable between floors via the cavity. The foam
insulation reduced my annual heating bill by 25%, and soon paid for
itself.

At the time I remember a brief cancer scare in the newspapers about
homes treated with this foam - but that ultimately came to nothing.

I had assumed that my current house, built in 1997, would have had the
wall cavities filled with insulation slabs at the time of building -
but some recent drilling through the exterior walls confirms that I
was wrong about that. Maybe the current building regulations for
insulation were not in place in 1997.

David