ZONES Unleash your imagination in our Wonderworld Sidewalk with Snow Partial Driveway / Snow Melting Compact crush rock | 5/8 inch treated plywood. 1 inch styrofoam insulation Heating System: Tankless Water Heater – 150,000 BTU Natural Gas heating: 4 Zones: Driveway, Sidewalk, Patio and 12 FT X 20 FT Greenhouse. These 4 Zones are working great just using the heating system. -45 gallons of 50/50 glycol Zone 2 – Sidewalk Compact crush rock | 5/8 inch treated plywood. 1 inch styrofoam insulation