Slab deflection

What slab deflection means

Slab deflection is the vertical movement of a slab under its own weight, imposed loads, or long-term creep. Some movement is expected, but uncontrolled deflection affects finishes, partitions, doors, drainage, and ceiling systems below.

Why it creates late cost

Deflection problems are often discovered by non-structural symptoms: tiles crack, water ponds, doors bind, ceilings show lines, or partitions separate. By then the structure is hard to access and finishes are already installed.

What to coordinate

• Structural span, depth, support, and loading assumptions.
• Screed, floor finish, drainage falls, and partition details that rely on slab geometry.
• Any heavy equipment, pool edge, planter, or facade load added after design freeze.