Definition of "underfloor" []

• Located beneath the floor. (adjective)
• A layer of flooring beneath the main floor surface. (noun)

Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License

• "Heat is distributed by a low-temperature central heating system such as underfloor heating which ensures a cosy climate at all times."
• "Now it has more than its fair share of creature comforts such as underfloor heating, windows in the roof and a dramatic spiral staircase."
• "The plumber watched anxiously in case there was a hydronic leak in the underfloor heating system, but all was well."