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Installing In-Floor Electric Radiant Heat

Construction How-To, Flooring Installation, Radiant Heat November 13, 2015 Sonia







My wife and I recently bought a home built with an unfinished basement and a concrete floor that we decided to turn into a welcoming space our kids could use as a playroom. They are still very young and spend a lot of time playing on the floor. We decided to install a lightweight rollout in-floor electric radiant heat system below a new floating floor as a way to supplement the natural warmth in the room and make it a cozy space for them to play. I did most of the work myself.

The first thing I did is cover the concrete floor with a roll-out vapor barrier. I then built a plywood subfloor.

Here’s how I installed the radiant system.

Step by Step

1 Qwarmth_Install_Sweep

Step 1: Sweep the subfloor to remove all dust, dirt, stray nails and screws and other debris to have a clean working surface. Leave nothing behind to telegraph through the underlayment or finished flooring.

2 Qwarmth_Install_measure from wall

Step 2: Draw a sketch of the intended layout of the radiant heat system, including the intended locations of the floor sensor, the thermostat and the junction box, making sure the factory-attached wires at the ends of the radiant mats are on the same side of the room as the junction box.

Be careful to follow instructions. The system I used requires at least 6 inches left between the edges of the closest mats and the wall to have enough space to run the wires to the junction box.

3 Qwarmth_Install_rollout_underlayment

Step 3: Here I rolled out a radiant-heat-ready underlayment called QuietWalk from MP Global Products, which covered the entire floor area. The underlayment includes a vapor barrier to help manage moisture above the subfloor and below the finished floor. It also cushions the floor to absorb sound and minimize the clicking noises from walking on a floating floor, and has an R-value of 0.5, which will help keep the basement warmer in the winter.

4 Qwarmth_Install_butt_seams_together

Step 4: The next step is to butt the seams of the underlayment, using duct tape to hold them in place. This underlayment has good compression resistance so it did not compress under my knees while I was taping.

5 Qwarmth_Install_rollout0

Step 5: I then rolled out the panels of QuietWarmth Radiant Floor Heating. I fit them to the layout of the room by cutting with scissors along the dashed lines between the radiant ink elements. I taped and insulated the cut edges with the included Kapton insulating disks. The panels come in several width/length configurations, so it was easy to fit the layout of the basement with minimal cutting.

I chose Perfectly Warm Radiant Heat Film because it was designed specifically for floating engineered wood and laminate floors (and some floating tile floors) and can be installed over underlayment. The ultra-thin wireless filament is just 0.016-in. thick.