Measurements and material terms
Start with the quantity, then check its units and endpoints. These definitions explain the guides; they do not set building requirements.
- Rise
Vertical difference between the named start and end levels. Total stair rise differs from the rise of one step. Use mm, cm, m, or labelled feet/inches.
See it in a guide- Horizontal run
Horizontal distance between the chosen endpoints, not the length along the slope. Use the same length system as the rise.
See it in a guide- Going / tread run
Horizontal advance from one tread nosing to the next. It differs from the full depth of a tread board, which can include an overhang.
See it in a guide- Pitch angle
Angle to the horizontal, shown in degrees (°). Roof or stair “pitch” can also be expressed as a ratio; read the field’s unit.
See it in a guide- Gradient / percent slope
Rise divided by horizontal run, multiplied by 100. A percentage is not a degree value.
See it in a guide- Clear gap
Empty distance between adjacent faces. It excludes the width of a baluster or board; centre spacing includes that width.
See it in a guide- Centre spacing
Distance from the centre of one repeated member to the next. For equal widths, it equals clear gap plus member width.
See it in a guide- Concrete cover
Distance from the concrete face to the nearest surface of reinforcement, not to the bar centre. Enter the specified cover; the guide does not select it.
See it in a guide- Lap / overlap
Length over which adjoining bars or sheets overlap. It uses material without increasing covered length by the same amount; the required lap comes from the project or specification.
See it in a guide- Mixed yield
Volume obtained from one bag when mixed under the stated conditions, usually L or m³ per bag. Bag weight in kg is a different quantity.
See it in a guide- Coverage
Area covered by a stated quantity under stated conditions. For paint, m²/L is the reciprocal of consumption in L/m²; check the number of coats.
See it in a guide- Net volume
Geometric volume before an extra allowance. It uses cubic units (m³), not square units (m²).
See it in a guide- Required volume
Net volume plus the allowance you chose. It is not automatically the rounded supplier order, bag count or truck capacity.
See it in a guide- Bulk density
Mass per bulk volume, such as kg/m³. Loose, wet and compacted material can have different values; use a value for the actual supplied state.
See it in a guide- Datum / reference level
Chosen level from which elevations are expressed. A local zero differs from an absolute elevation system; label the reference before comparing results.
See it in a guide- Stock length / cut length
Stock is the available piece before cutting; cut length is the requested finished piece. Total installed length alone does not determine the purchase count.
See it in a guide
Official building sources
Choose the jurisdiction of the project, not the language of this page. These starting points help you find applicable documents; Pro² does not determine compliance or approve a structural design.
- Australia — ABCB — National Construction Code
National code portal. Find NCC editions and homeowner guidance. Confirm the applicable edition and variations with your state or territory authority.
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- Canada — NRC — Codes Canada
National model codes and adoption information. Find model code publications and provincial or territorial adoption information. A national model edition alone does not identify the rules for your project.
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- United States — FEMA — Building Code Adoption Tracking
Government adoption overview. Use the adoption overview to locate state and local context, then confirm the applicable code and amendments with the local building department.
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- England — GOV.UK — Approved Documents
Building regulations guidance. Find guidance by subject, including stairs and protection from falling. Check the document’s scope, effective date and transitional provisions.
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- Wales — GOV.WALES — Approved documents
Welsh building regulations guidance. Use the Welsh documents and amendment slips; do not substitute the English collection.
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- Scotland — gov.scot — Building standards
Technical handbooks and procedural guidance. Find the domestic or non-domestic handbook and the relevant edition. The Scottish system is separate from the Approved Documents for England and Wales.
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