Stitch Raft Foundation: When & How It Connects Adjacent Rafts
A stitch raft foundation (stitch slab or stitch beam between rafts) ties two or more adjacent mat foundations so they behave as one system under differential settlement and lateral load. It is common when a building straddles an existing structure or expansion joint.
Why stitch rafts?
- Limit differential settlement between old and new blocks
- Transfer horizontal forces across a construction joint
- Provide continuity where full monolithic raft is impractical
For general mat design see raft (mat) foundations.
Typical details
Stitch elements are heavily reinforced RCC bands — often 300–600 mm deep — cast after both rafts exist or in a sequenced pour with dowels. Width spans the gap plus development length into each raft.
Stitch raft vs normal raft
A normal raft is one continuous slab under a footprint. A stitch raft system is two rafts + connecting stitch. The stitch does not replace bearing area; it shares load and controls movement.
FAQ
Is stitch raft the same as combined footing?
No. Combined footings join column loads on one pad. Stitch rafts join two mat systems — see combined footing for column pairs.
Disclaimer: Educational only. Disclaimer
Tanmay Arora, is an Architect with an experience of 13+ years. He is a Management Grad with a post Graduate Diploma in Building Construction and Materials. Tanmay has worked with renowned firms. He has graduated in Bachelor of Architecture. His deep interest in Architecture and Civil Engineering and his experience has made him one of the best architects a client can think of.
