Floor insulation

[everythingcrossed]

We have recently bought a lovely flat in a 1970s block - it's lovely accept the floor is absolutely freezing. It has laminate flooring on top of (I think) a concrete floor which is built over the block's garages so there is lots of cold, subterranean air blowing around down there. I want to pull up the laminate (which is nice and fairly new) and put down insulation before relaying the laminate boards - what would you recommend? Obviously the thinner, the better so we don't have to trim doors too much.

TIA

except not accept...

start by checking if it is concrete.

Insulation is proportional to its thickness. I think you will need at least an inch to do any good.

Luckily, heat loss through floors is fairly low because there is no convection current, and if the floor is concrete, there should be no draught.

Carpet and underlay would do the trick.