Use a specialized foam panel called Bekotec to lock the PEX tubing in place, cover it with a sand-and-cement mix, and tile away. (See below for a shopping list, tools, and steps.)
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Shopping List for How to Install DIY Radiant Floor Heating:
Bekotec-BRS foam edging [https://amzn.to/2AcDcFD]
Bekotec foam panels [https://amzn.to/2NbAwR9]
PEX tubing [https://amzn.to/2LoxOFS]
Bekotec THERM-RH 75 PVC clamps [https://amzn.to/2N8AM3p]
Sand [https://amzn.to/2N79hHD] and portland cement [https://amzn.to/34Egkgg]. Get enough for a 5:1 sand-to-cement ratio
Tools List for How to Install DIY Radiant Floor Heating:
4-foot level [https://amzn.to/2LHmZhl]
tape measure [https://amzn.to/32vuIWg]
breakaway knife [https://amzn.to/2LpDYpr]
pipe cutter [https://amzn.to/34Dwgzk]
wheelbarrow [https://amzn.to/2LqsrpZ] or mixing tub [https://amzn.to/2Lr54fO] for mixing concrete
shovel [https://amzn.to/32zeE64] or hoe [https://amzn.to/32DGheq] for mixing concrete
Radiant floor heating is probably the best way to heat up any space. It’s comfortable, quiet, and energy efficient. Although electric radiant heat is a popular choice for small projects, retiling a bathroom, say, hydronic, or water-based, radiant provides the ultimate in efficiency for bigger projects or an extensive remodel.
If you want to DIY hydronic radiant, you can use a specially engineered foam panel from Schluter Systems called Bekotec. You lay the panels directly on the floor, press-fit PEX tubing into them, and add a thin layer of specially mixed concrete, five parts sand to one part portland cement.
The panels provide a modest thermal break (R3), so you don’t have to install an extra layer of insulation. Using this system adds less than 1 3/4 inches, including concrete, versus about 4 inches for the old-school method of tying tubing to wire mesh. That leaves you more headroom in basement applications. And the thin slab will heat up and cool down more quickly, allowing you to use lower water temperatures and save on your heating bill. Overall, it makes for a more responsive radiant slab.
Steps for How to Install DIY Radiant Floor Heating:
1. Prep floor with leveling compound, if necessary.
2. Clean floor and install foam edging.
3. Lay first row of click-together panels.
4. Measure and trim the row’s last panel to fit.
5. Cover the remaining area with panels.
6. Determine PEX spacing: 6-, 9-, or 12-inch rows.
7. Press-fit PEX between “studs” in panels.
8. Cover area with one continuous loop of PEX.
9. Leave extra tubing at boiler-room end for plumber to make connections.
10. Mix up a batch of “dry pack” concrete with a 5:1 ratio of sand to portland cement.
11. Spread and level over PEX, leaving a minimum of 5/16 inch of material above foam “studs.”
12. Allow concrete to cure for a few days, then install your flooring of choice.
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How to Install DIY Radiant Floor Heating |This Old House