1.Subfloor needs to be solid and strong enough to support the flooring. Do not lay this product over carpet
2.Do not use this product under some kinds of cheap or not durable vinyl floors (peel N stick, vinyl sheet, 2-5 mm PVC glue down or click, <4.5mm SPC or EVP, <6.5mm WPC), <8mm Laminate, cork floor or floor with cork underlay, or floor with underlay. The above mentioned products have the risks of locking area broken (locking area will not be strong enough if products are too thin), or water / moisture / mold damages on cork (cork is water resistant, but not waterproof, though our product is waterproof)