Joints & Crack Control

Plan joints to control shrinkage and restraint cracking—get layout, timing, and depth right.

Also see: Finishing · Curing · Specs & Mixes

Layout

Panel aspect ratio typically ≤ 1.5:1; keep joint spacing consistent.
Place joints at reentrant corners and changes in section; isolate columns/penetrations.
Coordinate with load paths, sawcut access, and slab restraints (walls, footings, embeds).

Timing & Depth

Cut as soon as raveling stops; late sawcuts = random cracking.
Depth ≈ 1/4 slab thickness (min 1"). For thinner toppings, confirm with the designer.
Consider early-entry saws per manufacturer limits; verify groove depth.

Details & Sealing

Dowel or keyway load transfer as specified; protect devices during finishing.
Sealants per traffic/liquid exposure; proper recess/width ratio; clean/dry groove.
Honor joints in toppings/finishes—don’t bridge restraint points.

References

ACI 302.1R — Floor & Slab Construction
ACI 224R — Control of Cracking in Concrete Structures
ACI 360R — Slab-on-Ground Design (as applicable)

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