Guide to Installing PEX Tubing in Concrete Slab Floors

Radiant underfloor heating is highly efficient and can ensure that your home remains comfortable. Heated concrete floors keep your feet toasty warm, as concrete is an excellent heat conductor.

Unfortunately, many homeowners forget crucial steps during installation, rendering the floor’s heating system inefficient. This guide covers how to install PEX tubing in concrete slab floors.

Sometimes, the job is better left to professionals though, so if you need help, consider contacting J. Blanton.

How PEX Tubing Helps in Concrete Floor Heating

PEX is a type of cross-linked polyethylene plastic tubing that’s used in hydronic radiant heating systems. Heated water circulates through these systems through the PEX tubing installed under the flooring, so the tubing must be installed before pouring concrete over it.

During installation, the tubing is stapled to foam insulation or tied off to a mesh grid so that it floats in the middle of the concrete slab. The latter creates the most efficient heating system.

With this, heat from the floor gets distributed evenly throughout your house.

How to Install PEX Tubing in Concrete Slab Floors

A perfect PEX tubing arrangement under the concrete slab is the secret to successful floor heating. But you only have one chance to pour the concrete slab, so it’s crucial to correctly place the PEX tubing beneath.

So how do you install PEX tubing on a concrete slab? Here’s what it involves.

Step 1: Install Insulation

Non-insulated slabs account for about 70% of energy waste in in-floor heating systems, so before installing the PEX tubing, it’s best to add insulation material to the subsurface.

Prepare the ground properly before installing the tubing by ensuring it’s flat and leveled so the insulation fits in place. You can also install a vapor barrier beneath the insulation.

If you plan to enclose the tubes within the slab, cover the insulation using reinforcing wire or rebar.

Step 2: Lay the PEX Tubing Over the Insulation

Now that the insulation is in place, the next step in how to install PEX tubing in concrete slabs is actually installing the tubing on the insulation.

Apply the tubing along one wall and curve it on the adjacent wall. Then turn it again so it runs along the opposite wall. Attaching the tubing to reinforcements is ideal.

Staple the tubing to fasten it to the insulation—make sure you don’t accidentally puncture the tubing when doing so. Alternatively, you can attach the tubing to a reinforcing wire or rebar using wire ties instead of stapling it directly on the insulation.

Continue aligning the PEX tubing bit by bit over the insulation, leaving a space of 9 inches between the tubing sections. It’s important to space the PEX tubing so heat is distributed evenly across the room.

Also keep in mind that the tubing will be empty when pouring the concrete, so the pipes should run deeply enough that they won’t float.

Step 3: Twist the Tubing Throughout into 6 to 8 Inch Arcs

Next, for how to install PEX tubing, twist the tubing sections into 6 to 8 inch arcs to create a set of “S” patterns while leading the tubing back to the starting point. Then continue tying or stapling the tubing until you cover the entire floor area.

By the time you’re finished applying the tubing, there should be two ends of PEX tubing left open near one another in one part of the room. Ensure the hot and cold ends of the PEX tubing are well-supported on the wall to prevent them from collapsing.

Step 4: Pour Concrete Over the Tubing

Now that the tubing is well-positioned on the floor, it’s time to pour concrete on the floor to cover the tubing and create a slab. You can do it yourself, but it’s best to hire a contractor to do it.

The concrete slab should be 2 inches thick at minimum to allow the hydronic system to work efficiently.

Benefits of In-Floor Heating Using PEX Tubing

Now that you know how to install PEX tubing in concrete slab structures, let’s go over the benefits of having this kind of tubing to heat your floor.

• Comfort: Investing in in-floor radiant heating helps to keep your concrete floor comfortable. The heat from the concrete floor will be evenly distributed so you won’t have to deal with unpredictable cold and hot spots when walking barefoot, especially during the winter.


• Better Indoor Air Quality: Radiant in-floor heating doesn’t blow any air through dirty and dusty ducts, reducing the circulation of air pollutants in your home. Since this home heating technology doesn’t compromise indoor air quality, it’s an excellent alternative to traditional forced air heat. For this reason, it’s highly beneficial for homeowners with allergies or asthma.


• Silent Home Heating: Unlike forced-air heating systems, radiant in-floor heating doesn’t emit any noise. In this way, you can avoid the noisy fans of forced air systems and pipes clanging inside your walls.

J. Blanton Plumbing can help you install PEX tubing

Even after learning how to install PEX tubing in concrete slab structures, the actual process can be a bit technical for someone without experience.

If you feel that it’s too much, consider hiring a reputable plumber like J. Blanton Plumbing to help you.

Contact J. Blanton today to install PEX tubing in your home!