Can PEX pipe be installed in concrete or under concrete slab?

This is a question that must be directed to the PEX pipe manufacturer. The suitability of different brands of PEX may vary from one manufacturer to the next. Therefore, Boshart is not able to provide an across-the-board answer.

However, the answer to this question will typically be yes, based on the information provided by several prominent PEX pipe manufacturers.

PEX pipe is commonly used in hydronic radiant floor heating systems. Most PEX pipe can be installed under a concrete slab and can also be encased within a slab.

When PEX is installed beneath or in concrete there are a number of precautions that the system designer / installer must consider including but not limited to those listed below.

#1 – You must adhere to all the applicable national and local building / plumbing codes.

#2 – You must follow the PEX pipe manufacturer’s installation instructions.

#3 – Design the system to use one continuous length of PEX pipe. Make sure that there are no sharp bends which could kink the pipe. Always refer to the PEX pipe manufacturer’s installation instructions which include minimum bend radius specifications. Since PEX pipe is supplied in coils, you can avoid using any fittings to make connections in the PEX under or in the slab.

#4 - Prepare the ground properly before installing the insulation, ensuring it is flat and levelled so the insulation fits in place evenly. Non-insulated slabs account for about 70% of energy waste in in-floor heating systems, so before installing the PEX tubing, it is best to add insulation material to the subsurface.

#5 - If you plan to enclose the tubes within the slab, cover the insulation using reinforcing wire or rebar. The PEX is secured to a mesh grid so that it floats in the middle of the concrete slab to create the most efficient heating system. Another popular method of installation is to use insulating hydronic radiant floor heating panels with snap in design to secure the PEX pipe in place.

#6 – Before pouring concrete, make sure that there are absolutely no chemical additives used in the concrete mix which could potentially react with PEX tubing.

#7 - Where PEX pipe penetrates a concrete slab, it must be protected with a non-metallic sleeve at the penetration point.

Additional Resources:

https://www.ciph.com/page/hydronics_council

https://www.plasticpipe.org/BuildingConstruction/BuildingConstruction/Publications/PEX-Design-Guide.aspx