Construction calculators

17 construction calculators: duration and line-of-balance programme, labour days, plaster and mortar, laydown area, wellpoint dewatering, bored piles, soil nails, striking time, waterproofing, gutters and asphalt.

17 tools, most used first

⬡High Strength Bolt Torque CalculatorPreload by size and class, with snug and final torque.▤Plaster and Render CalculatorMortar, cement and sand by layer for internal plastering.◐Mortar Mix Design CalculatorTrial strength, cement, water and sand, and the mix by mass.⚒Labour Days and Crew CalculatorMan-days, crew size and labour cost from output rates.⇉Line-of-Balance Duration CalculatorRhythmic flow duration with overlap and break adjustments.▥Material Storage Area CalculatorNet footprint, total area and a suggested bay size.◍Dewatering CalculatorPit inflow by the equivalent-well method, then well count.⊙Bored Pile Concrete and Rebar CalculatorConcrete volume, overbreak factor and reinforcement for bored piles.◷Formwork Striking Time EstimatorStriking times for side and soffit forms by member and temperature.▧Waterproofing Area and Membrane CalculatorTotal area with upstands, membrane rolls and primer.⊵Wellpoint Dewatering CalculatorPoints along the pit perimeter: count, spacing, header length and daily pumping.⊿Soil Nail Wall CalculatorNail count and length, grout volume, facing concrete and mesh.◷Construction Duration CalculatorQuantity × labour norm ÷ crew gives the days you need.◫Bathroom Waterproofing CalculatorFloor, walls and detail strips, with coating and membrane quantities.⌄Roof Gutter CalculatorDesign flow, what the gutter can carry, and how many downpipes.≣Waterstop CalculatorJoint length gives waterstop length, area and weight.▩Asphalt Quantity CalculatorArea × thickness × density gives tonnage, then bitumen content.

What this group solves

This group is for planning: durations, flow, crew sizes, laydown space and dewatering choice. Duration comes from the number of sections, the cycle time per section and any lag, while labour days come from quantity divided by output norm — and the two must agree, because a programme that does not match its crew is the most common reason a method statement comes back.

The other half is specialist processes: dewatering sized from total inflow and yield per well, bored piles from diameter and depth, soil nails from face area and grout take, waterproofing from area plus laps and detail reinforcement, waterstops from joint length plus laps, and asphalt where bitumen ratio is not the same as bitumen content. Every one of these has an add-on that gets forgotten, and each is broken out separately here.

FAQ

How do I estimate a construction duration?

Quantity divided by the output norm gives labour days, then divide by crew size for duration in days, then arrange the sections as a flow. With n sections, m trades and cycle time t, a balanced flow takes (n + m − 1) × t plus technical breaks less any overlap. Only the critical path can compress the total.

How many wellpoints do I need?

Total pit inflow divided by yield per well — typically 1.5-2.5 m³/h — gives the count. Spacing runs 0.8-1.6 m, and a single-stage system draws down 3-6 m; beyond that you need two or more stages. Riser length is drawdown plus filter length plus 0.5 m above ground.

How many rolls of waterproofing membrane?

Area divided by roll coverage (commonly 10 m²), times one plus lap waste. With 100 mm side laps and 150 mm end laps that is 10-15%. Add detail strips 300-500 mm wide at corners, penetrations and construction joints — usually another 5-8%, and the part most often left out of the order.

Other groups

Concrete Rebar Masonry Finishes Earthwork Temporary Works Costing M&E Material weights Area and volume Unit conversion Code Lookup

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.