As a heating design engineer, I spec a lot of hydronic radiant-floor heating systems for both residential and commercial jobs. I would probably spec more residential systems, however, if they weren't so expensive. Though initially interested, many homeowners are eventually scared off by the high costs. One of the reasons for the high cost has to do with the cost of the thin slab itself. The usual method of installing the thin slab for hydronic floor heating uses a self-leveling gypsum-based underlayment, such as Gyp-Crete. The underlayment is typically poured near the end of the job, after all the walls are up and the house has been closed in. These systems must be installed by a certified
