In basements a layer of closed cell R10 insulation panels are laid down, into which usually 1/2″ Oxygen Barrier PEX tubing is inserted at 9″ or 12″ spacing. On top of that is the concrete floor is then poured. Each loop of PEX tubing is 300′ long at the maximum. On upper floors there is no need for insulation ad the tubing is stapled onto the subfloor. The tubing is then covered by a special mixture of concrete such as AccuRadiant.