Do you recommend installing a vapor barrier under the ProCore Plus LVP on an at-grade wood floor partially over a crawl space? What type barrier?

Hello Dave - thank you for your inquiry. I’m going to paste instructions below directly from our installation guide to help answer your questions. These instructions can be found on our website www.procorefloors.com Wood Subfloors: All wooden subfloors and substrates must be dry and in compliance with the moisture content percent (MC-%) for your region. Regional values are freely available by searching “moisture map of wood” images. Test using a non-destructive electronic moisture meter, following the product instructions. The subfloor must comply with local building codes, have at least 18-in. of well-ventilated air space below and have a suitable vapor retarder to isolate the subfloor from ground cover and outdoor conditions. Wood subfloors must have a total thickness of at least 1-in. Sleepers must not make direct contact with concrete or earth. If necessary, install an underlayment grade plywood with a minimum thickness of 1/4-in. on the surface. The underlayment must be installed in the opposite direction to the subfloor, following ASTM F1482 Standard Practice for Installation and Preparation of Panel Type Underlayments to Receive Resilient Flooring. Note: plywood is a water-sensitive subfloor that may become damaged or deformed by topical liquids. To protect wood subfloors from topical water exposure, follow the Wet Area Guidelines below. Unsuitable Subfloors: These include but are not limited to: any floating or loose floor coverings, hardwood, carpet, cushion vinyl, rubber, cork, foam, asphalt tile, any additional acoustic underlayment, any substrate with visible mold, mildew, or fungi and any substrate in wet areas, such as inside showers and saunas. Do not install directly over any adhesive or adhesive residue of any kind. Do not install directly over radiant heated substrate or in recreation vehicles, campers or boats. Note: Existing hardwood floor coverings will swell when exposed to moisture: vinyl floor covering may restrict the movement of moisture in hardwood, which may result in flooring failure, especially when installed on or below grade. Some hardwood floor coverings may also discolor vinyl floor covering, which is excluded from warranty coverage. By electing to install over any existing floor covering releases the manufacturer from any responsibility regarding the suitability and continued performance of that product, including any resulting effect on the new floor covering, such as indentations and damaged locking mechanisms. Is the wood subfloor actual wood flooring or the osb / plywood underlayment? Hope these guidelines help you determine next steps. Thank you!