We used 4” HydroFoam, PEX spaced 18”, #5 rebar spaced 12” OC and 6” thick slab in our garage/shop area. We normally keep our garage at 60F, but if needed, we will bring it to a higher temp over the course of two days. 12” PEX spacing is the maximum one should use for living spaces to ensure no floor temp gradients can be detected with bare feet, but one may need to go to an even closer spacing (e.g., 9 or 6”) depending on the heat flux required to offset the heat loss of the given room. 18” PEX spacing is fine for commercial floors and residential garage/shops where floor temp gradient isn’t a concern. We haven’t had any regrets having the capability to heat our garage/shop area. One really needs to accomplish a Manual J or equivalent room-by-room heat loss analysis and then a proper hydronic radiant floor heating design to sort out the PEX spacing, circuit supply temps/flow rates, and resulting head loss to properly size the pump and heat source. |