Field & trade terms
Control joint
Also called: contraction joint
A control joint is a deliberate groove in a slab, wall or masonry run that gives the material a place to crack as it shrinks and moves. Concrete and mortar always shrink as they cure and swing with temperature, and something has to give — the joint creates a weakened line so the crack follows it rather than wandering across a finished surface. It doesn't stop movement; it steers where the movement shows.
How it shows up on site
In slabs you see control joints as saw-cut or tooled lines on a grid, cut deep enough and soon enough to work. In masonry they're vertical joints spaced along a wall, often with a backer and sealant. Spacing and depth are set by the design; a joint too shallow or too far apart just moves the crack somewhere else.
What an inspector looks at
The check is that joints are where the drawings put them, at the right depth and spacing, and cut in time — a saw cut made too late lets the slab crack on its own first. Missed or shallow joints get logged before the surface is finished or a topping is placed.
RTI is photo-gated, so joint layout and depth are shot in place — the cut pattern and spacing shown against the slab or wall, the record that the joints were run as designed and not added as an afterthought.
Standards it's verified against
Checklists that put control joint to work
Free, field-ready checklists, each with the photo every item needs before it can be submitted.
Related terms
- Cold jointA weak seam left in concrete when fresh material is placed against a batch that has already started to set, so the two never fully bond.
- Curing (concrete)Keeping fresh concrete moist and at temperature long enough for it to gain the strength the mix was designed to reach.
- Sealant jointA joint filled with elastic sealant to keep water and air out while still flexing as the two sides move apart and together.
- 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.
- FlashingThin sheet material lapped into an assembly to direct water back out at joints, edges and openings before it can get behind the finish.
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.