I am considering using the Environ II system in our basement under Kahrs floating engineered hardwood.

I’m a little confused on the underlayment…I read that an insulating over concrete is recommended. Is that in addition to the Kahrs’ underlayment?
Where are the Environ mats installed, directly beneath the wood?

Edit: the title should say under wood

SMA,

We apologize for not having posted a reply sooner. We are currently going through some system changes.

In reply, insulating over concrete is almost a necessity. A concrete slab will act like a giant heatsink, pulling anywhere from 10 to 20 degrees worth of the heat output into it before the heating system ever heats the flooring above.
Some engineered flooring has the underlayment attached to it as oppose to a loose underlayment. If this is the case, underlayment other than that which is attached to the flooring is needed as the underlayment attached to the flooring will push the heat back downwards.
Environ II is installed atop the subfloor (or atop the underlayment if the subfloor is concrete) and below the engineered or floating flooring.
Please let us know if you should have any other questions! Thanks SMA!

Thanks for the reply. So, let me see if I’ve got it straight.

Kahrs does not have the underlayment attached, but they do require their own underlayment to keep the warranty in place. You recommend cork as an insulator over concrete, I believe.

So is this recommended sequence: concrete floor, cork, Kahrs underlayment, heat mat, wood flooring?

SMA,

Your recommended system installation method sounds perfectly sound to me. The one thing I would also mention is that if the Kahrs own underlayment is sufficient in relation to thickness and R value (at least 1/4 inch thick for maximum insulating underlayment effectiveness and 2.6 R) then the cork underlayment would not be necessary. If that is not the case, then stick with what you so succinctly concluded! Let us know if we can help with anything else!
Thanks SMA!