Subfloor panels. We have 35 of them. See link below for the product. They have been used for a floor in an unfinished basement. $100 obo for all of them. https://www.rona.ca/en/product/barricade-subfloor-air-plus-panel-air-gap-technology-235-x-235-cbgap9750240240-6334032?viewStore=61040p