Retrofitting Hydronic Heating into an Uninsulated Basement Slab

Direct the heat toward the feet

Retrofitting in-floor heat is a great way to warm up a chilly basement bathroom. But unless you have insulation under the heating system, your customers are going to spend fat stacks of Benjies heating the earth every month.

Step by step:

• To keep the heat where you want it, cut out the slab before installing the heating system.
• Dig deep enough to allow for gravel, insulation, and a slab on top.
• Cover the earth with compacted gravel to support the slab and keep water from wicking in.
• Reinforced plastic over the gravel stops water vapor.
• Rigid insulation comes next surrounding the new slab on all five sides.
• You will need some sort of steel reinforcement, either wire mesh or rebar and then install the hydronic tubing.
• Pour the slab over the tubing, let it cure, and cover the whole assembly with flooring—and be confident that your customers Benjies will stay in the bank.

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• SECTION R402 BUILDING THERMAL ENVELOPE
• SECTION R403 SYSTEMS

• Section 402: Building Thermal Envelope
• R502.1.1.1: Building Thermal Envelope (existing building)
• R 502.1.1.2 Heating and Cooling Systems (existing building)

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