Project Guide

Installing Radiant Heat in Floors

1
STAPLE THE MATS IN PLACE
STAPLE THE MATS IN PLACE
  • Unroll the mat material and cut it to length with scissors.
  • Strip the insulation off an end of the two wires that run the length of the mat.
  • Turn the mat so those ends are facing the wires that will bring power to it.
  • Have a helper hold the mats against the bottom of the subfloor while you staple them in place.
  • Do not install the 2 feet or so of mat to which you’ll be attaching wire.
2
CONNECT THE WIRES
CONNECT THE WIRES
  • Crimp a black wire on one mat wire and a white wire on the other.
  • Slip the crimping sleeve over the wire at the end of the mat and put a 14-gauge stranded, tinned copper wire inside.
  • Squeeze the crimping tool to crush the sleeve tightly over the wires.
  • Cover the connection with electrician’s tape
3
INSTALL INSULATION
INSTALL INSULATION

Once all the mats are in place, install insulation between the joists, keeping it the recommended distance from the heating mats.

4
INSTALLING ABOVE THE SUBFLOOR
INSTALLING ABOVE THE SUBFLOOR

If you can’t get to the base of a floor, install electric mats above the subfloor. Keep in mind that they will have to be covered by a protective layer of gypsum or concrete. Staple the mats on top of the subfloor and wire as directed.


While some manufacturers advise spreading thin-set over their mats, it can be difficult to keep the floor flat and level. Mats that include a self-leveling gypsum mixture over them is best. Let it dry the appropriate length of time, then cover it with flooring as if you were installing the flooring over a concrete base. In bathrooms and kitchens, install a moisture barrier to protect the gypsum.


Installing Hydronic Heat


Start at a corner of the room and run tubing to the other side between the joists. Feed it into the bay between the neighboring joists through predrilled holes. When you have snaked tubing from one side of the room to the other, hold it in place with aluminum plates stapled to the subfloor.

5
DRILL THE HOLES FOR TUBING
DRILL THE HOLES FOR TUBING
  • Drill a hole at one end of each bay so you can feed the tubing into the neighboring bay.
  • Plan where each hole needs to be and drill them all before installation.
  • Drill an oversize hole, as directed by the manufacturer, using a Forstner or similar bit. Spade bits aren’t durable enough for a big job like this. Space will be tight and the drill bit will have a thick shank, so use a right-angle drill with a ½-inch chuck.
6
THREAD THE TUBING
THREAD THE TUBING
  • Put a coil of PEX tubing on the floor at one end of the first bay while a helper stands on the other end of the bay.
  • Walk over to your helper while holding one end of the tubing.
  • Put the tubing through the hole in the joist and pull it back to the other side of the room while your helper feeds it through the hole.
  • When you reach the other side of the room, feed the tubing through the hole in the joist.
  • Have your helper walk the tubing back to the other side of the room and feed it through the next joist hole.
  • Continue until you’ve run tubing under the entire floor.
7
FASTEN THE DISSIPATION PLATES
FASTEN THE DISSIPATION PLAGES
  • Once the tubing is in place, go back to where you began the tube.
  • Hold the tubing against the underside of the subfloor and put an aluminum plate over it.
  • Staple the plate to the subfloor.
  • Space the plates along the tubing as directed by the manufacturer.
  • If you have multiple loops, put a piece of tape on the ends of the tubing and label which end is connected to the heat source and which returns to the heat source.
  • Have an installer connect the valves, manifolds and pipes required to finish the job.
8
ABOVE THE FLOOR HYDRONIC HEAT INSTALLATION
ABOVE THE FLOOR HYDRONIC HEAT INSTALLATION

Like electric systems, you can install hydronic systems in a concrete, mortar or gypsum bed.


It’s easier to install the tubing in specially made plywood with precut channels. Nail the plywood in place as you would a subfloor or underlayment. At the wall, install pieces with curved grooves that make a U-turn, and send the tubing back across the room in another groove.


You can install carpeting and wood flooring directly over the plywood. Vinyl requires underlayment, and ceramic and stone floors should be set in a mortar bed or on cement backerboard.