- Q.What is cellular-core PVC
pipe? Is it as strong as solid PVC pipe?
A.Julius Ballanco, P.E.,
president of J.B. Engineering and Code Consulting
in Munster, Ind., responds: Unlike solid PVC
pipe, cellular-core PVC pipe is a co-extruded
product with at least three different layers. The
inside and outside walls are solid PVC, while the
inner core is cellular (or foamed) PVC, a material
that includes tiny bubbles of entrained air.
Cellular-core PVC pipe is available in various wall
thicknesses, including Schedule 40 pipe for DWV and
thin-wall sewer-grade pipe. For pipe manufacturers,
the main advantage of cellular-core PVC is lower
cost, since it requires less resin to make than
The model plumbing codes permit the use of
either solid-wall PVC or cellular-core PVC pipe in
residential plumbing systems. However,
cellular-core PVC pipe is not as stiff as solid PVC
pipe. At 5% deflection, a 4-inch cellular-core PVC
pipe has a minimum pipe stiffness of 200
pounds-force per square inch, while a 4-inch
solid-wall PVC pipe has a minimum pipe stiffness of
310 pounds-force per square inch.