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Raft Foundation Verification Checklist

Essential Checklist+

Complete these critical checks before approving the work or proceeding to the next construction stage.

✓16 Inspection Points
✓5 Verification Categories
✓Design & Soil Confirmation+
  • Raft (rather than isolated/strip footings) is confirmed as the correct foundation type from the geotechnical report and structural drawing, not assumed.
  • Raft thickness, mesh diameter, and spacing (bottom and top, both directions) are taken directly from the approved structural drawing, not estimated.
  • Soil bearing capacity used in design matches the actual geotechnical investigation for this site, not an assumed generic value.
  • Column loads and positions used in the raft design match the latest approved structural drawing revision.
  • Punching shear at each column location has been checked by the structural engineer, since it commonly governs raft thickness rather than simple bending.
✓Excavation & Blinding+
  • Excavation is taken to the level and extent shown on the drawing, with side slopes/shoring stable for the working depth.
  • Formation (excavated base) is firm, level, and free of loose soil, standing water, or soft spots before blinding is poured.
✓Reinforcement Verification+
  • Bottom mesh diameter and spacing (both X and Y directions) match the structural drawing, with bars evenly spaced and properly tied at every intersection.
  • Top mesh (where specified) is included at the correct locations and extent, not omitted as a simplification.
  • Cover blocks/chairs are placed to maintain the specified bottom, top, and side cover throughout the pour, not just at the initial tying stage.
  • Additional/extra top reinforcement around column locations (if specified for punching shear or hogging) is placed exactly where shown, not generalized across the whole raft.
  • Column starter bars/dowels projecting up from the raft are positioned accurately and securely braced before the pour, so they don't shift out of position.
✓Casting & Curing+
  • Concrete is poured in the sequence and joint locations specified by the structural engineer, given the raft's typically large single-pour volume.
  • Concrete is properly compacted/vibrated throughout the raft's full thickness and around congested reinforcement near columns, without segregating the mix.
  • Raft is cured (kept moist) for the applicable minimum period appropriate to its mass/thickness, which is typically longer than a standard slab given the larger pour volume and reduced surface-to-volume ratio.
✓Final Check+
  • Raft top surface level and column starter positions are verified against the drawing before column formwork begins above it.
Full QC Checklist+

Verify design/soil confirmation, excavation/blinding, reinforcement, casting/curing, and final check.

✓26 Inspection Points
✓5 Verification Categories
✓Design & Soil Confirmation+
  • Raft (rather than isolated/strip footings) is confirmed as the correct foundation type from the geotechnical report and structural drawing, not assumed.
  • Raft thickness, mesh diameter, and spacing (bottom and top, both directions) are taken directly from the approved structural drawing, not estimated.
  • Soil bearing capacity used in design matches the actual geotechnical investigation for this site, not an assumed generic value.
  • Column loads and positions used in the raft design match the latest approved structural drawing revision.
  • Punching shear at each column location has been checked by the structural engineer, since it commonly governs raft thickness rather than simple bending.
  • Construction joint locations (if the raft can't be poured in one continuous operation) are planned and detailed by the structural engineer in advance, not decided ad hoc on site.
✓Excavation & Blinding+
  • Excavation is taken to the level and extent shown on the drawing, with side slopes/shoring stable for the working depth.
  • Formation (excavated base) is firm, level, and free of loose soil, standing water, or soft spots before blinding is poured.
  • PCC/blinding layer is poured to the specified thickness and allowed to set before reinforcement is placed on it.
  • Any waterproofing or damp-proof membrane specified beneath or around the raft is placed and lapped correctly before reinforcement fixing begins.
✓Reinforcement Verification+
  • Bottom mesh diameter and spacing (both X and Y directions) match the structural drawing, with bars evenly spaced and properly tied at every intersection.
  • Top mesh (where specified) is included at the correct locations and extent, not omitted as a simplification.
  • Cover blocks/chairs are placed to maintain the specified bottom, top, and side cover throughout the pour, not just at the initial tying stage.
  • Additional/extra top reinforcement around column locations (if specified for punching shear or hogging) is placed exactly where shown, not generalized across the whole raft.
  • Lap splice locations are staggered per the applicable code and structural drawing, not concentrated at the same line across the mesh.
  • Column starter bars/dowels projecting up from the raft are positioned accurately and securely braced before the pour, so they don't shift out of position.
  • Any service penetrations (plumbing, drainage) through the raft are coordinated with the reinforcement layout before the pour, not cut through placed bars afterward.
✓Casting & Curing+
  • Concrete is poured in the sequence and joint locations specified by the structural engineer, given the raft's typically large single-pour volume.
  • Concrete is properly compacted/vibrated throughout the raft's full thickness and around congested reinforcement near columns, without segregating the mix.
  • Raft is cured (kept moist) for the applicable minimum period appropriate to its mass/thickness, which is typically longer than a standard slab given the larger pour volume and reduced surface-to-volume ratio.
  • Edge shuttering (where used) is not removed, and no load is placed on the raft edge, before adequate strength has developed.
  • Ambient/curing temperature is monitored for mass-concrete effects (heat of hydration) on a thick raft, with a cooling/curing plan if the pour is large enough to be a concern.
✓Final Check+
  • Total concrete and steel used is reconciled against this calculator's estimate (or the project BBS) before closing out the item in records.
  • Raft top surface level and column starter positions are verified against the drawing before column formwork begins above it.
  • No visible honeycombing, cracking, or exposed reinforcement on the finished raft surface or edges.
  • Completed raft is inspected and signed off by the site engineer, with a photographic record kept, before backfilling or covering begins.
Inspection Notes+
Use the latest approved drawings, specifications, and site measurements.
Complete all critical checks before proceeding to the next work stage.
Record deviations and confirm rectification where required.

Related Calculators & Guides

Raft Foundation CalculatorOpen the related calculator and verify the current project inputs.

FAQ

Use it after collecting the project inputs and again before approving or closing the relevant work stage.
No. It supports verification but does not replace approved drawings, specifications, codes, manufacturer requirements, or professional inspection.