Field & trade terms
Waterstop
Also called: water stop, water-stop
A waterstop is a continuous strip — PVC, rubber or a swelling bentonite product — cast into or set across a joint in concrete so that water cannot travel through the joint. Concrete joints, whether the planned break between two pours or a moving expansion joint, are the natural weak line for water to find, and the waterstop is the barrier embedded right at that line to stop it. It is standard in below-grade walls, water-holding structures and slabs where the joint would otherwise be a leak path.
Why it matters
A waterstop is buried in the concrete, so it is a one-shot install — you cannot come back and fix it after the joint is poured. If it is misplaced, torn, folded over or not continuous at a splice, the joint leaks, and the repair is injection or excavation from the other side. The value is entirely in getting it right before the second pour.
Its most common failures are the ones nobody photographs: a lap that was never welded or spliced, a section knocked out of position during placement, or concrete that honeycombed around it and left a void. Verifying it in place before the pour is the only real chance to catch those.
How it shows up on site
Waterstop confirmed continuous and centered on the joint, splices properly joined, and the installation photographed in position at the pre-pour inspection before the concrete closes it in for good.
Standards it's verified against
Checklists that put waterstop to work
Free, field-ready checklists, each with the photo every item needs before it can be submitted.
Related terms
- HoneycombVoids in hardened concrete where the mortar did not fill around the coarse aggregate, leaving a rough, porous surface with stones showing.
- EfflorescenceThe white, powdery salt deposit that appears on masonry or concrete when water moving through the material carries dissolved salts to the surface.
- Weep holeA small opening left at the base of a cavity wall or window so water that gets behind the face has a path back out.
- Holiday testAn electrical test that finds pinholes, thin spots and gaps — holidays — in a protective coating or membrane that the eye would miss.
- MEP (mechanical, electrical, plumbing)The mechanical, electrical and plumbing trades — the systems run through a building's structure that get inspected at rough-in and again at final.
- FirestoppingSealing openings where pipe, conduit or cable pass through a fire-rated wall or floor so the assembly's rating is restored.
Knowing the term is step one. Proving it is the job.
RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.