Vadir barrier: a concrete slab underlayment with all-in-one void form, air barrier, drainage plane, insulation and radon protection

In combination with an earthen floor surface of an excavated area and a concrete foundation slab overlying said earthen floor surface, at least one concrete foundation slab underlayment residing overtop of said floor surface and beneath said concrete slab, said underlayment comprising:

• an upper vapour barrier layer that comprises at least one material that is substantially impermeable to gas and vapour, and that resides in underlying adjacency to the concrete foundation slab;
• and
• a set of insulation bodies that are materially distinct from the at least one material of the upper vapour barrier layer, and are secured to said upper vapour barrier layer in underlying relation thereto at a central non-margin area thereof such that said insulation bodies reside oppositely of the concrete foundation slab across said upper vapour barrier layer;
• a cover layer residing atop the underlayment and beneath the concrete foundation slab, wherein the cover layer is more rigid than said flexible sheeting of the upper vapour barrier layer and resides in overlying relation to the upper vapour barrier layer and the insulation bodies therebeneath,
• wherein:
• said upper vapour barrier layer spans fully over all of said insulation bodies, said insulation bodies are spaced apart from one another at least at lower ends thereof that reside opposite of the upper vapour barrier layer in offset relation therefrom nearer to the earthen floor surface, thereby leaving drainage/air spaces open between the lower ends of said insulation bodies beneath the concrete foundation slab and the upper vapour barrier and overtop of the earthen floor surface;
• said at least one material of the upper vapour barrier layer comprises flexible sheeting, at least at outer margins of said upper vapour barrier layer that reside along respective perimeter edges of the vapour barrier layer outside the central non-margin area occupied by the insulation bodies;
• and
• the vapour barrier layer comprises a primary upper sheet that has greater rigidity than the flexible sheeting and occupies the central non-margin area at which the insulation bodies are secured, and a set of flexible perimeter flaps that are formed of said flexible sheeting, are attached directly to the primary upper sheet, and span in overhanging relation therefrom around a perimeter thereof at said outer margins of said vapour barrier layer;
• whereby the upper vapour barrier layer forms a gas and moisture barrier beneath said concrete foundation slab, and the insulation bodies and the drainage/air spaces therebetween form a combination of void spaces, drainage channels and insulation blocks overtop of said earthen floor surface and beneath said concrete foundation slab and said upper vapour barrier layer.