Which foundation systems are acceptable for tilt-up construction, and which are not allowed?

• A. Shallow footings, drilled piers, pad footings, continuous footings, grade beams, stem walls are acceptable; rafts or mat slabs cannot be used.
• B. Rafts or mat slabs are acceptable.
• C. Only raft slabs are acceptable.
• D. All foundation types are acceptable.

Answer: (A)

In tilt-up construction, foundations must provide stable, discrete support that aligns with the wall panels and reliably transfers loads into the soil. The acceptable set includes shallow footings, drilled piers, pad footings, continuous footings, grade beams, and stem walls. These options give proper bearing at defined edges or lines, support the panels during lifting, and integrate with the floor and wall connections.

Rafts or mat slabs are not allowed in this context because they distribute loads over a large area as one thick mat, which complicates the edge bearing and anchorage needed for tilt-up panels and can lead to differential settlement and unpredictable panel behavior. The tilt-up sequence and detailing rely on individual footings and grade beams that align with panel edges, making the listed foundations the appropriate choice.