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Plinth Filling Cost Calculator Plinth filling material cost estimator

Estimate total plinth filling cost from fill, PCC, and DPM rates.

Plinth Footprint

Multiple Different-Sized Sections?

ℹ️Internal footprint length to be filled, from the foundation/plinth drawing.

ℹ️Internal footprint width to be filled.

ℹ️Set to more than 1 if several identical rooms/blocks share this same footprint and fill depth.

Fill Layer

ℹ️Height from formation level to the underside of the PCC bed; commonly 150-450 mm for residential plinths.

ℹ️Extra loose volume needed over the compacted volume — pre-filled per material, adjust if your supplier's data differs.

PCC Bed

ℹ️Commonly 50-100 mm for a residential floor base.

DPM (Damp-Proof Membrane)

Include DPM?

ℹ️Accounts for the minimum ~150mm lap required at every joint between sheets.

ℹ️Extra allowance for the upturn at edges/walls and offcuts.

Cost

Enable Cost Estimation?

ℹ️Use the tonne option to match the common truckload/tipper pricing convention for bulk fill, alongside the m³ (loose volume) rate suppliers may quote instead.

ℹ️Use the cft option to match the common site-mixed concrete convention, alongside the m³ rate RMC suppliers typically quote.

ℹ️Optional buffer for unknowns — supplier rate variance, delivery charges, or material substitution. Commonly 5-15%.

For a 140.00 (1,507 sqft) plinth footprint filled 200 mm deep with soil / select fill, you need approximately 59.17 tonnes of fill material and 11.025 (389.3 cft) of PCC bed concrete.

Compacted Fill

Material: Soil / Select Fill

Compacted volume: 28.000 (988.8 cft)

Loose volume (before wastage): 32.200 (1,137.1 cft)

Loose volume (with wastage): 33.810 (1,194.0 cft)

Material to order: 59.17 tonnes

PCC Bed (1:4:8)

Thickness: 75 mm

Total concrete: 11.025 (389.34 cft)

Cement: 37.6 bags

Sand: 5.224 (184.5 cft)

Aggregate: 10.448 (369.0 cft)

DPM (Damp-Proof Membrane)

Area with laps/wastage: 154.00 (1,657.6 sqft)

Roll coverage: 120.00/roll

Rolls needed: 2

Cost Summary

Fill material cost: 27,048

PCC bed cost: 49,613

DPM cost: 2,400

Total estimated cost: 79,061

Assumptions Used

Fill: loose volume = compacted volume × (1 + compaction%), then wastage on top | PCC: dry volume factor 1.54, wastage applied to cement/sand/aggregate together | DPM: rolls = ceil(area × (1 + wastage%) ÷ (roll area × (1 − overlap%))) | Flooring/screed/tiling above the DPM is outside this calculator's scope — see Limitations.

Approximate results for planning only. Verify with a professional.

Unsure where the DPM should sit relative to the PCC bed? Plinth Filling Guide →

Plinth Filling Cross-Section

Formation levelCompacted FillSoil / Select FillPCC Bed (1:4:8)DPM (membrane)Finished floor level (flooring by others)Fill: 200 mm75 mmPlinth footprint: 14 m × 10 mDiagram simplified for clarity, not to scale.

Looking for the verification checklist, reference tables, or tips and mistakes?See the complete Plinth Filling Calculator.

Plinth filling cost estimate

This page has cost estimation switched on with DPM included, so all three layers contribute to one combined total: a 14 m x 10 m footprint (140 m²) needs 33.81 m³ of loose fill at 800/m³ (27,048 for fill), 11.025 m³ of final PCC concrete at 4,500/m³ (49,612.5 for PCC), and 2 DPM rolls at 1,200/roll (2,400 for DPM) — a combined base cost of about 79,060.5 before any contingency.

Fill and PCC rates can each be switched between a per-m³ and an alternate unit (per tonne for fill, per cft for PCC) to match however your supplier actually quotes, and a contingency percentage (0% by default) can be added on top of the combined base cost for rate uncertainty or delivery surcharges.

  • Default footprint: 14 m x 10 m (140 m²), DPM included.
  • Fill cost 27,048 + PCC cost 49,612.5 + DPM cost 2,400.
  • Combined base cost: ~79,060.5 (before contingency).

How Is Plinth Filling Calculated?

The calculation happens in three parts — compacted fill, PCC bed, and DPM — then an optional cost estimate on top.

Step 1 — Footprint Area

Area = Length × Width

Total Area = Area × Number of Identical Sections

If sections differ in size: Total Area = Sum of (Length × Width × Count) for every section

The footprint is the internal area to be filled, taken from the foundation/plinth drawing. Number of Identical Sections multiplies the whole result for repeated rooms/blocks of the same size; for rooms of different sizes, switch on "Multiple Different-Sized Sections" and the calculator sums every row's area into one combined total automatically.

Step 2 — Compacted Fill

Compacted Volume = Total Area × Fill Depth

Loose Volume = Compacted Volume × (1 + Compaction %)

Loose Volume (with wastage) = Loose Volume × (1 + Wastage %)

Order Quantity (tonnes) = Loose Volume (with wastage) × Material Density ÷ 1000

Delivered fill material is loose and has more air voids than it will once compacted in place, so the compaction percentage inflates the compacted (finished) volume into the loose volume you actually need to order; wastage is then applied on top of that loose volume, and the resulting figure converts directly to a tonnage using the material's density — the same convention this site's Backfill and Aggregate Coverage calculators use. For "Custom Fill Material", the density you enter is used directly in this step instead of a preset figure.

Step 3 — PCC Bed

Wet Volume = Total Footprint Area × PCC Thickness

Dry Volume = Wet Volume × 1.54

Cement / Sand / Aggregate = Dry Volume split by mix ratio parts

Wastage % applied to cement bags, sand, and aggregate together

This uses the same footprint area as Step 1 (so it stays correct whether you're using a single footprint or several differently-sized sections) and the same PCC formula as this site's dedicated PCC Calculator — a thin, lean-mix concrete bed that gives a firm, level surface for the DPM and floor slab above, not a structural element in its own right.

Step 4 — DPM (Damp-Proof Membrane)

Final Area = Total Area × (1 + Wastage %)

Roll Coverage = Roll Length × Roll Width × (1 − Overlap %)

Rolls Needed = ROUND UP(Final Area ÷ Roll Coverage)

Wastage accounts for the edge upturn and offcuts, while the overlap percentage accounts for the minimum lap required at every joint between adjoining sheets so ground moisture can't find a path through.

Step 5 — Add Contingency (Optional)

Base Cost = Fill Cost + PCC Cost + DPM Cost

Contingency Amount = Base Cost × (Contingency % ÷ 100)

Total Cost = Base Cost + Contingency Amount

Contingency is an optional buffer on top of the combined base cost to cover unexpected variance — supplier rate changes, delivery charges, or material substitution. It defaults to 0%; a commonly used range is 5-15%.

Worked Example

This example walks through your current inputs above, using the same steps as the Formula section. Each table shows the calculation, the values substituted in, and the result it produces.

Input Values Used

InputValueWhy it is used
Plinth footprint14 m × 10 m, 1 section(s)Sets the area every layer's volume is built on
Fill material / depthSoil / Select Fill, 200 mmSets fill density and compacted volume
Compaction / wastage15% compaction, 5% wastageConverts compacted volume into the loose quantity to order
PCC bed75 mm, 1:4:8, 5% wastageSets PCC wet volume and cement/sand/aggregate split
DPM roll30 m × 4 m, 10% overlap, 10% wastageSets roll coverage area and rolls needed
Rates & contingency800 per fill, 4,500 per PCCSets fill, PCC, DPM cost and total estimated cost

Step 1 — Footprint Area

The footprint area is the base every layer above is built on — fill volume, PCC volume, and DPM area all scale directly from it.

CalculationSubstitutionResult
Area14 m × 10 m140.000
Total area140.00 × 1140.000 m² (1,506.95 sqft)

Step 2 — Compacted Fill

The compacted volume is what the finished, settled fill will occupy. Compaction inflates that into the loose volume, wastage inflates it once more into the loose volume actually ordered, and that final volume converts directly into a tonnage using the material's density — the same figure the cost step below uses.

CalculationSubstitutionResult
Compacted volume140.00 m² × 200mm28.000
Loose volume28.000 m³ × 1.1532.200
Loose volume (with wastage)32.200 m³ × 1.0533.810 m³ (1,194.0 cft)
Order quantity33.810 m³ × 1750 kg/m³ ÷ 100059.17 tonnes

Step 3 — PCC Bed

The PCC bed volume comes from the same total footprint area as Step 1, not the fill's compacted volume — it's a separate, thin layer cast on top of the finished fill.

CalculationSubstitutionResult
Wet volume140.00 m² × 75mm10.500
With 5% wastage10.500 × 1.0511.025 m³ (389.3 cft, 37.6 bags)

Step 4 — DPM

The DPM area is inflated by wastage first (for edge upturn and offcuts), then divided by each roll's effective coverage — the roll area reduced by the overlap needed at every lap joint.

CalculationSubstitutionResult
Final area140.00 × 1.10154.00
Roll coverage30m × 4m × 0.90108.00
Rolls neededROUND UP(154.00 ÷ 108.00)2 rolls

Step 5 — Cost & Contingency

CalculationSubstitutionResult
Fill cost33.810 m³ × 800/m³27,048
PCC cost11.025 m³ × 4,500/m³49,613
DPM cost2 rolls × price/roll2,400
Base costFill + PCC + DPM79,061
Total costBase cost79,061

Therefore, this 140.0 m² plinth needs approximately 59.17 tonnes of fill material, 11.025 of PCC bed concrete, and 2 rolls of DPM, costing around 79,061.

This page keeps things focused on the calculation above. For the full construction guide — verification checklist, reference tables, usage steps, tips, common mistakes, and limitations.See the complete Plinth Filling Calculator.

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FAQ

Three components add together: fill cost (33.81 m³ loose fill x 800/m³ = 27,048), PCC cost (11.025 m³ final wet concrete x 4,500/m³ = 49,612.5), and DPM cost (2 rolls x 1,200/roll = 2,400), giving a base cost of 27,048 + 49,612.5 + 2,400 = 79,060.5.
Fill cost is calculated on the loose volume with wastage already applied (33.81 m³ here), since that's the actual quantity you'd need to order and pay for from a supplier — not the smaller 28 m³ compacted (finished) volume.