Precast Manhole Take-off (Procurement)

Enter each manhole's cover level, invert level and pipe sizes: the calculator picks the manhole type from the outgoing pipe and counts base elements, 0.90 / 0.60 / 0.30 m rings, top slabs, cast-iron covers, steps and necks, plus excavation, compaction, blinding, sand bedding and backfill - one procurement list for the whole network.

1 · Manholes

#	Manhole	Cover level (m)	Invert level (m)	Outlet Ø (mm)	Inlets	Inlet Ø (mm)	Type

Manhole type follows the outgoing pipe: ≤ Ø600 → Ø1200 · Ø700–800 → Ø1500 · Ø900–2500 → rectangular (cast in situ). Rows are kept in this browser until you clear them.

2 · Pipe runs (for trench excavation, sand and backfill - optional)

#	From manhole	To manhole	Pipe Ø (mm)	Length (m)	Trench width (m, optional)

⚙️ Project settings (site values by default)

Base floor below invert (m)

Base inner height - Ø1200 (m)

Base inner height - Ø1500 (m)

Top slab thickness (m)

Minimum gap above slab (m)

Neck from gap of (m)

Neck / opening inner Ø (m)

Neck wall thickness (m)

Ring wall thickness (m)

Rectangular chamber wall (m)

First step above pipe crown (m)

Step spacing (m)

Last step below cover (m)

Working space around manhole (m)

Excavation below structure (m)

Blinding concrete (m)

Trench depth below invert (m)

Sand bed under pipe (m)

Sand cover above pipe crown (m)

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Precast Manhole Take-off

Procurement and BOQ quantities for storm water and sanitary sewer networks built with precast circular manholes.

Manhole type (outgoing pipe governs):
• Up to Ø600 → circular Ø1200 (base 0.90 + 0.30 m)
• Ø700–800 → circular Ø1500 (base 1.20 + 0.30 m)
• Ø900–1000 → rectangular 3000 × 3500 mm
• Ø1100–1500 → rectangular 3500 × 4000 mm
• Ø1600–2500 → rectangular 5000 × 5000 mm

Rings: 0.90 / 0.60 / 0.30 m, fewest rings; the rest up to the cover level stays as the gap above the slab (≥ 0.05 m, a neck from 0.20 m).

Steps: from 0.10 m above the outlet crown, every 0.30 m, up to 0.30 m below the cover.

Key Points:

Any number of manholes and pipe runs
Manhole size from the outgoing pipe Ø
Base types by size, outlet Ø and inlets
Ring stack, slab, cover, neck and steps per manhole
Earthworks: excavation, compaction, blinding, bed, sand, backfill
Procurement list, PDF and CSV export

Calculation Steps:

Enter all required parameters
Click "Update Calculation"
Review results and analysis