I thought that all modern houses had to have cavity wall insulation.

However my neighbour has found that their 8 year old house does not
have cavity wall insulation. Apparently the builders (Redrow) were
able to get away with using just thermalite blocks and no cavity wall
insulation.

We are now planning to have the insulation installed, but what were
the regs 8 years ago and should Redrow have been allowed to get away
with not installing cavity wall insulation?

Incidently we thought the house was a bit cold and the heating bills
high.