We are going to lay a massive spruce floor in a newly built house with underfloor heating. We don't have a concrete slab but instead a crawl space from Isolergrund, which is an insulated, heated crawl space with negative pressure (as it is ventilated by the exhaust air heat pump). The air in the crawl space is drawn down from the house above through the floor joists and out through the regular ventilation.
In the Flooring Industry's guidelines for wooden floors on underfloor heating, it states that a vapor barrier should be used under the floor if laying parquet flooring on underfloor heating. Regarding massive flooring, it states that "under massive wooden floors, the vapor barrier should be used in cases where the subfloor can be suspected of transporting moisture, for example, a slab on ground." Should this be interpreted as not needing a vapor barrier under massive flooring if it is n o t suspected to be damp underneath?
