Overview
What the PN Series Is — and Isn't
PN Series is a putty-type, hydrophilic rubber waterstrip made from a rubber compound blended with water-swelling additives. It sits flat on the face of a concrete construction joint, bonded either by its own adhesive backing or held with nails, and does nothing at all until groundwater or seepage reaches it. On contact with water, the rubber absorbs moisture and swells — expanding into the pores, honeycombing and micro-gaps that ordinary concrete pours leave behind, and generating contact pressure against the surrounding concrete as it does.
That reactive, gap-filling behavior is what separates it from a mechanical waterstop. A PVC waterstop works whether or not it ever meets water: its ribbed profile is cast into the middle of the pour and physically blocks the path length. A water-swelling waterstrip only starts working once water actually shows up — which also means it can reseal itself around small settlement cracks that appear later, something a rigid PVC profile cannot do on its own.
Because the seal depends on confinement, PN Series is built for joints where movement is minimal: horizontal and vertical construction joints (also called cold joints), pipe and sleeve penetrations, and connections between precast elements. It is not a substitute for a PVC expansion joint waterstop in a joint designed to move.
When to Specify PN Series vs. a PVC Waterstop
Choose PN Series for straightforward construction/cold joints with no designed movement — wall-to-footing joints, pour-to-pour joints in basement slabs, and around pipe penetrations.
Choose a PVC waterstop (see the BC or SO Series) where the joint is expected to expand, contract or shift, since those joints need a mechanical barrier that keeps working through movement, not just contact pressure.
