Ask for the layout
Joint locations influence both appearance and how a slab accommodates expected behavior. Discuss them alongside the dimensions, corners and transitions. A decorative pattern does not remove the need to plan joints.
Recognize different purposes
Contraction and isolation details do different jobs. NRMCA’s Concrete in Practice resources explain why jointing is part of slab design. The appropriate arrangement depends on the actual project; a homeowner should not need to specify it from a generic diagram.
Review connections to existing work
A new slab beside a house, step or older driveway needs a deliberate connection detail. Ask how the interface will allow the intended behavior and how it will look. Exact color matching should not be assumed across separate placements.
Understand limitations
Jointing helps manage where movement and cracking may occur, but it is not a promise of crack-free concrete. Ask how joints will be formed or cut, whether sealing is included and what maintenance is appropriate. Keep those details in the written scope.
Further reading: NRMCA Concrete in Practice. General guidance does not replace a site-specific assessment.