I am trying to get approval for a new home addition on Charlotte, NC for using 3" of foam, a vapor barrier and then two layers of 3/4" plywood instead of a concrete slab. How can I get this approved under code? I have seen other builders do this, so it must be possible. this is what Chat gpt says, but I'd rather avoid having to pay $1000 for an engineering stamp to approve it.
In the North Carolina Residential Code, foundation requirements for floors and slabs typically appear in sections related to foundation construction and insulation, specifically Chapter 4 (Foundations) and Chapter 5 (Floors). Since a slabless slab differs from a traditional concrete slab in materials and load distribution, it may be allowed if it meets specific requirements around load-bearing capacity, thermal insulation, and moisture control.
Key sections to review include:
Chapter 4 – Foundations (Sections R401 through R406): Focuses on general foundation construction, including moisture barriers, soil treatment, and load-bearing criteria.
Chapter 5 – Floors (Sections R501 through R507): Covers floor framing and subflooring, especially where alternative materials like foam and plywood may be acceptable if they meet certain standards. |