Dallas clay soil, concrete movement and crack questions

Start with water and grade

Look for roof runoff, irrigation leaks, low spots and water trapped beside the slab. Alternating saturation and drying can change support conditions. Pouring new concrete without correcting concentrated drainage can reproduce the problem under a cleaner surface.

Document elevations and the intended direction of surface drainage. A driveway or patio should not solve its own drainage by sending water toward the building or a neighbor.

Make the invisible scope visible

The proposal should state removal limits, subgrade treatment, base material, slab thickness, reinforcement, joint layout, connection details and curing. Ask how soft or undocumented fill will be handled if uncovered. ‘Standard concrete’ is not a complete assembly.

• Map crack widths, offsets and locations before demolition.
• Distinguish nonstructural flatwork from foundations and load-bearing slabs.
• Use a qualified engineer when movement could involve the building structure.
• Keep heavy loads off the work for the curing period specified by the contractor.

Ask what the repair is designed to accomplish

A surface patch can improve appearance but may not stop movement. Slab replacement, leveling and structural repair address different conditions. Get the contractor to name the suspected cause, evidence and limits of the proposed remedy in writing.