Foundation / Slab foundation
Raft foundation
/rɑːft ˌfaʊnˈdeɪ.ʃən/noun
From raft, a floating platform, describing how the slab “floats” on the ground.
Definition
A continuous reinforced concrete slab extending under the whole building, spreading loads over the entire footprint where soil bearing capacity is low or variable.
Fig. 59 — Raft foundation: schematic studyNOT TO SCALE
Illustrative study — Raft foundation · AI-generatedSAMPLE IMAGE
Photo study — Raft foundation · AI-generated00:06
Structural & construction notes
Rafts reduce differential settlement and can bridge soft spots. Edge thickening or downstand beams stiffen the perimeter; design balances soil pressure against slab bending.
An educational reference. Project-specific design requires professional guidance.