DIY Doctor UK DIY Forums

Hi, I would like to insulat my loft but I want to know what is the best loft insulation i.e thermal and accouist value money can buy

Have a look at the Celotex, Kingspan, Rockwall sites. They should give you u values, and probably db values as well, but would be interested to hear why you would acoustically insulate loft area.

While sheet materials are suitable for many things, if you want the best level of insulation then you should look at sprayed in foam.
The thing with sheet materials is, they are very difficult to fit perfectly.
Unfortunately, wherever a gap or crack is left in insulation then, the wind can suck your expensive warm air out.
Sprayed in foam will fit perfectly to every odd shape and give you the perfect insulation.
Incidentally, sound has a habit of finding its way through every hole, gap and crack - again sprayed in foam will provide an effective barrier against noise.
Note: Because there will be a great difference in the insulation levels between the joists and the insulation, leading to ghosting, it is advisable to fit polystyrene or similar sheets below the joists so that you do not end up with grey lines across the ceiling.