In order for a radiant heating system to be effective, it's important to ensure that the underside of the slab is well insulated so that heat isn't absorbed by the ground but rather diffused into the surrounding air. Poor insulation will result in increased heating costs and reduced system responsiveness.

Depending on the chosen type of insulation, the method of securing the pipes to the floor will vary. This is the aspect we will discuss below.

Does the slab require insulation before the PEX piping installation?

Yes. For a basement, a slab-on-grade, or a monolithic slab, you first need to install insulation. The three most effective insulation methods for radiant floor heating are polyurethane spray foam insulation, rigid insulating panels, or ISORAD hydronic insulation. 

Note: respecting the Canadian building code is primordial. The code requires, by law, that all buildings have a minimum thermal resistance of R-10.

How should PEX piping be secured when insulating with polyurethane spray foam insulation?

Tie-wraps or zip ties are used to secure the tubing to the mesh. Once the flooring has been sprayed with urethane foam, sheets of wire mesh must be installed over the foam to solidify the slab and fix the tubing. The wired mesh requires a slight elevation to ensure the concrete’s rigidity is maximised. 

Tip: When laying the wire mesh, aligning the tiles can be used as a template to facilitate the installation of the PEX pipes.

How should my PEX tubing be secured with foam board insulation?

Sheets of wire mesh must be laid down to secure the pipes with zip ties. In general, when the foam board insulation is fitted one inside the other (before installing the metal mesh) a polythene vapour barrier must be installed to seal your building’s flooring efficiently. In some places, the foam board insulation will surely have to be drilled or cut to allow plumbing pipes to pass through or around columns. Procuring spray cans of urethane are important to insulate these spaces and avoid unnecessary heat loss.

How should my PEX tubing be secured when insulating with rigid hydronic in-floor heating insulation?

First of all, the piping must be fitted between the cells. This method of insulation is the fastest way to install your PEX piping. If the pipes tend to rise in certain places, we recommend adding U-Clips.

Note: it is very important the piping does not move during the pouring of the concrete. To ensure your building is properly sealed, a vapor barrier (polythene) must be placed under the insulation panels. For this type of installation, it is not necessary to have wire mesh unless your concrete installer recommends it. We recommend purchasing spray cans of urethane to insulate holes or gaps created to fit water pipes into your building.