"Tony Hayes" wrote in message
...
My neighbour is laying the floor in his new bungalow - 4 inch thick
polystyrene insulation sheets covered with chipboard tongue and groove.
He
intends running plastic central heating pipes under the floor and is
looking
for the best way of cutting channels in the insulation to take the piping.



why on earth use 4" of polystyrene ? .... you can use polyurethane, it is
much better for use with underfloor heating.
It is more dense, and much higher insulating value than polystyrene .


But if you want to cut it ... you could use a soldewering iron, but simpler
to use a stanley knife set to correct depth of cut - cut left & right side
then use a fork to scrape out the waste.


Rick