Every slab is going to crack — shrinkage during cure guarantees it. Control joints are how you decide where: a deliberate weak line the crack follows instead of wandering across your driveway. There are two ways to make that line.
Tooled joints
Cut into the wet concrete during finishing, with a grooving tool. Pros: part of the pour itself — no second visit, no extra step. Rounded, traditional edges. Cons: the finisher is racing the set, and a rushed joint can end up too shallow. Depth is the whole game (more below), and wet-tooling makes depth harder to verify.
Saw-cut joints
Cut with a diamond blade after the concrete has set — timed in a real window: too early tears the surface, too late and the slab has already cracked wherever it pleased. Pros: crisp, straight, modern-looking lines, and cut depth you can measure and verify. Also the only option for adding joints to a slab that already exists. Cons: a second operation, and the timing has to be respected.
The part that actually matters: depth
Here's the thing both camps skip past: a joint that isn't deep enough — proportional to the slab's thickness — controls nothing. It's a groove for looks while the real crack runs diagonally past it. Most "my slab cracked outside the joints" stories are depth stories. Ask whoever pours your slab how deep the joints will be and how that was decided. A blank look is an answer too.
What we do
On our own pours we plan the joint layout before pour day — spacing matched to the slab, cuts at proper depth, method chosen for the job rather than habit. And for existing slabs poured without joints (red clay finds those fast), sawing proper joints in is one of the most cost-effective fixes in concrete: a straight line you planned instead of a jagged one you didn't.
