How do you install underfloor heating?

Find out everything you need to know to install your underfloor heating system!

00:06 Materials and tools required
00:12 Checking and rectifying the subfloor
00:25 Preparing thin-set mortar
00:35 Preparing the uncoupling membrane
00:39 Moistening the plywood
00:46 Applying thin-set mortar and laying the membrane
01:07 Use of compression roller and drying time
01:13 Testing the heating cable and probe + installing the cable in the wall
01:45 Laying the heating cable and probe in the membrane
02:10 Heating cable test
02:15 Cement application for floor covering installation
02:29 Heating cable test
02:33 Connection by a certified electrician

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Materials and tools required

Materials

• Underfloor uncoupling membrane
• Underfloor heating cable
• Cement
• Floor heating thermostat
• Floor probe
  
  Tools
• Bucket
• Megohmmeter
• Sponge
• Compression rollerGro
• ut and mortar mixer
• Wooden float (for membrane)
• Trowel

Checking and rectifying the subfloor

Make sure your plywood sheets are securely screwed down every 4”.

The subfloor surface must be free of all residues (glue, paint, plaster, etc.).

Rectify slight surface irregularities with a sander or scraper.

If your floor is not level, make sure it is before continuing with the installation (see video “How to prepare your subfloor for ceramic tiles”).

Preparing thin-set mortar

Mix the thin-set mortar for membrane installation according to the manufacturer's instructions.

For best transfer, add a little more water to make your thin-set mortar more liquid than recommended.

To bond the membrane, the thin-set mortar must have a fairly fluid consistency, yet be able to hold the trowel's impression.

Preparing the uncoupling membrane

Measure the surface where you're going to install the uncoupling membrane, then determine your starting point so as to have as few cuts as possible.

Moisten plywood

Moisten the plywood with a sponge previously soaked in water and wrung out to remove dust and prevent the plywood from absorbing water from the cement-glue during installation.

Applying thin-set mortar and laying the membrane

Apply a thin layer of thin-set mortar to the surface using the recommended trowel.

Go over the thin-set mortar with the serrated side, making sure that the lines are always in the same direction.

Level off any excess thin-set mortar at the joints to prevent overflow when installing the membrane.

Place the uncoupling membrane on the surface, applying pressure with a wooden trowel to ensure good adhesion to the thin-set mortar and remove air from under the membrane.

Work in small sections to prevent the cement-glue from drying out before you lay the membrane.

Use of compression roller and drying time

Use a compression roller to ensure that the membrane is well positioned and smooth, avoiding wrinkles and air bubbles.

Allow to dry according to manufacturer's instructions.

Testing the heating cable and probe + running the cable up the wall

It's important to test the heating cable 4 times during the entire floor heating installation process, in order to verify its quality and comply with warranty conditions.

The first test should be carried out while the cable is still coiled.

A megohmmeter is required to measure the insulation resistance of heating cables. For warranty purposes, it is also important to record the results of the various tests in the heating cable test logbook.

If you opt for a programmable thermostat, it's also important to test your thermostat sensor before tiling.

Once the heating wire has been installed in the wall, test the heating cable a second time to ensure that no breakage has occurred during installation.

Laying the heating cable and sensor in the membrane

Lay the heating cables in alternating 3-3 studs or 3-2 studs over the entire floor.

A 3-2 installation allows you to reach the desired temperature more quickly and increase heating power.

Avoid crossing or overlapping cables.

A buffer zone is recommended, as it is difficult to calculate exactly where the heating cable will end. This area can be used to conceal excess wire (e.g. under a vanity or raised cabinet). Heating cables can be laid 6” (150 mm) from the wall to create this buffer zone.

When installing the sensor, please ensure that it is equidistant from two heating cables.

Testing the heating cable

Re-test the heating cable to ensure that no breakage has occurred during installation.

Applying cement for floor covering installation

You can apply cement directly to the wire after it has been installed, or wait until you've installed your floor covering and carry out the filling at that time. Be careful not to damage the wires during this step.

Take care not to damage the wires during this step.

It's essential to ensure that all membrane cavities are completely filled when applying cement-glue.

Heating cable test

Once the membrane has been filled or the ceramic installed, test it again.

Connection by a certified electrician

Call in a certified electrician to connect the heating cables to the thermostat and the electrical circuit. After all tests and installation, you can put the floor into service (according to the manufacturer's recommended waiting time).

For an electric system, set the thermostat to the desired temperature and let the floor heat up.