I've brought a load of the Costco/Elka solid wood flooring to lay in my kitchen diner. (And thanks to the advice garnered from here, I know I can lay it as a floating floor and glue the Tongue and Groove ) I'm planning on putting down a combi DPM/Underlay over the existing concrete, but heres the catch - in roughly the middle of the floor I'll be bolting two metal stands through it to mount a radiator on. Each stand with have 3x 10-12mm holes drilled right through and about 40mm into the concrete for some no12 screws. (I'm sure this won't penetrate the building dampcourse, and in fact the existing plasterboard wall I knocked out was secured to the floor with steel nails driven about an 1.5" into the concrete and they show no signs of rust.) But obviously this is going to compromise the integrity of the dpm I put down for the new oak floor - should I be worried?