Floating Cork over Concrete

Q: I am planning to replace the carpet in my family room with a floating cork floor (Westhollow Cordoba Natural). I haven’t checked, but I’m pretty sure that the sub floor is concrete, since the family room was added on to the house sometime after the original build. What kind of underlayment would work best in this case. I know that I’ll probably need a vapor barrier (even though we really don’t have a moisture problem, I’d rather be safe than sorry in a few years), but I’m not sure if I’d need anything else. Noise is really not an issue, as this is a single family home, but the room does get cold in the winter, so I wouldn’t be opposed to putting in an underlayment to help with insulate the room. What are your thoughts?
Tracy
A: Before proceeding with any installation, make sure that you test the subfloor to ensure it is level. Just use an 8′ straight edge, even a 2″ x 4″ will suffice. If you find any high spots or low spots, it’s a good idea to use a self-leveling compound to flatten these out. If you do any leveling work, make sure you use a bit of latex additive to give it some elasticity when the concrete flexes during the seasons and give it plenty of time to cure before installing your new cork floor over it.
Ensure you use a moisture barrier and tape up all the seams with a wide seam tape to ensure good overlapping. For underlayment which insulates your best bet would be to use cork. Here at the office we have a great floating cork floor which is installed over 6mm cork underlayment. This not only adds some warmth to the floor via insulation, but also gives the floor a solid sound and feeling over foot, making it akin traditional hardwood floors, but with cork you have just enough softness that it will remain comfortable even for longer durations of standing.
At a minimum I would suggest using a 3mm cork as an underlayment, but 6mm is superb and well worth the small shift in floor height. If you are heavily concerned with floor temp, you could look into using an electric based radiant heat system such as BestHeat or NuHeat’s pads, but I think you should be set with just the flooring and underlayment.