This year I used fan fold 1/4 inch insulation as an underlayment. 30$ for 200 square feet.
http://www.menards.com/main/building-ma ... c-5778.htm
It might provide some small thermal break but I really was only concerned with it's resiliency and making the floor feel absolutely fantastic. It worked and it feels great underfoot.
[attachment=0:vnjbgguy]poolunderlay.jpg[/attachment:vnjbgguy]
http://www.menards.com/main/building-ma ... c-5778.htm
It might provide some small thermal break but I really was only concerned with it's resiliency and making the floor feel absolutely fantastic. It worked and it feels great underfoot.
[attachment=0:vnjbgguy]poolunderlay.jpg[/attachment:vnjbgguy]