Insulating under floors

[goodwood]

We have suspended timber floors and have the choice of lifting up the wooden floor, insulating and laying down a new wooden floor or saving the cost of this and laying a good underlay and carpet on the current floor. I would like to know if insulating will make a big difference or only a marginal difference over the underlay/carpet option.

Insulating and draughtproofing a floor is very important if you have bare floorboards.

If you are going to have thick underlay and carpet, it is not necessary.