Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
Backfill is filling the spaces around foundations and under the ground slab with selected soil in layers of set thickness, each watered and compacted.
Why it matters on a project
Soil type, layer thickness and moisture decide whether the fill stays stable or settles later.
Measurement and pricing
Measured in cubic metres, separating fill from excavated material and imported fill.
Worked example
Excavation of 120 m³ with 35 m³ of buried footings and ground beams: backfill is about 120 - 35 = 85 m³ compacted.
Common mistake
Backfilling with soil containing debris, large stones or organic matter.
Frequently asked questions
Can excavated soil be reused as fill?
If it meets the specification and is free of debris and organic matter; otherwise selected fill is imported.
Why is fill watered before compaction?
Compaction reaches maximum density near the optimum moisture content.
Related terms
- Compaction testA test proving backfill layers are compacted to the required density.
- Footings (foundations)Structural elements that transfer the building loads to the soil.
- Termite treatmentTreating the soil before pouring to protect the building from termites.
- Quantity take-offExtracting quantities from drawings under defined measurement rules, with a reference for every figure.
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