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Short Summary
Main recommendation: There is no single best subfloor system; the right choice depends on the house's age, moisture problems, thermal (warmth) needs, flooring type, and how the materials can be brought into the house. The speaker compares several options, from DRYCORE dimpled panels to DuraFoam and exterior membrane with OSB, and explains which problem each one solves best, noting he has no sponsor for the video.
Key Points
- Dimpled panels such as DRYCORE provide moisture management by creating an air space between the concrete and the floor, and tongue-and-groove panels that are tightly joined also give a thermal break.
- A thermal break matters because heat escapes through gaps; the speaker says a properly installed tight thermal break can raise the floor temperature by roughly five to seven degrees compared to no thermal break at all.
- Older homes built before about 1990 to 1995 often lack a moisture barrier under the concrete (vapor barriers weren't standard until then), making a dimpled subfloor especially useful there.
- Engineered or solid hardwood that must be nailed or stapled needs a thicker assembly, so an extra layer of 5/8-inch OSB is needed over thinner panels.
- Exterior foundation membrane with OSB costs about $1.50 per square foot and relies on very tight installation, but DuraFoam with OSB is actually cheaper at about $1.50 total (50 cents foam + ~$1 OSB), making it the most cost-effective option overall.
- Cost comparisons given in the video: DRYCORE about $2.10 per square foot (Canadian dollars), DRYCORE InSol Armor about $2.50 per square foot, DuraFoam about $0.50 per square foot (plus OSB at about $1), and exterior membrane with OSB about $1.50 per square foot.
Details Worth Noting
- Concrete instructions: Do a moisture test by taping a garbage bag to the concrete and checking the next morning; a wet spot under the bag means you need moisture management.
- Concrete instructions: Hammer tongue-and-groove panels fully tight so no gaps remain, because every gap becomes a cold spot and a path for moisture.
- Concrete instructions: Stagger the joints on panels such as InSol Armor for a better lock, and tape joints on the DMX One Step product.
- Concrete instructions: For fastening, use 2¾-inch-long, 3/16-inch-wide Tapcon screws with pan heads, drive them into concrete without cleaning out the dust, and use Tuck Tape to glue insulated panels together. If a hole is hard to connect, insert copper wire.
- Concrete instructions: Consider the delivery route; 4x8 sheets are heavy and need a large window or truck access, so lighter panels may be better for stairs or narrow access.
- Concrete instructions: Check finished floor height, since some panels add about 1⅜ inches, and make sure the first step off the landing still feels normal.
- The DMX One Step product is also rated for sound (IIC rating) and suits condos or concrete buildings, but it is only a thin underlayment, not a true subfloor.
- The speaker recommends a dimpled membrane when water comes through walls, and a thermal-break board when comfort is the main concern.
- Subfloor systems do not prevent flooding; they only manage moisture and improve comfort.
Bottom Line
Choose the subfloor based on your specific problem: dimpled membranes for moisture, rigid foam for warmth, and thicker OSB layers if you need to nail hardwood. Cost-effective options work only if installed carefully.
