Radiant In-Floor Heating

Q: Can radiant in-floor heating be installed under paving bricks? I’m building a new garage and would like to use something other than concrete for the floor. Will a system of hot water pipes work just as well without being encapsulated in concrete? I haven’t been able to find anyone who will answer this question with authority.

A: That's a great question, and to answer it I went to Doug Purdy, a radiant heating rep that I trust. Doug says yes, your plan will work fine. It probably won’t be quite as efficient as a conventional installation, but that won’t matter much in a garage. That said, Doug cautions that all radiant in-floor heating systems must be designed around heat loss calculations to determine pipe size and spacing. He also recommends you fill the system with a 30% food-grade propylene glycol mixture for freeze protection, just in case the system fails during cold weather.