Code Lookup calculators

8 code lookup tools: concrete cover, seismic class, column confinement zone, floor live load, maximum fire compartment, egress distance and width, and concrete strength assessment.

8 tools, most used first

▣Concrete Cover Thickness LookupMinimum cover from exposure class and member type, with every code correction applied.◈Seismic Detailing Class LookupIntensity, system and height in; detailing class and height check out.≣Column Confinement Zone CalculatorConfinement length, hoop spacing and bar size for each detailing class.▤Floor Live Load LookupPick an occupancy and read the characteristic live load in kN/m².◫Fire Compartment Area LookupCategory, fire rating and sprinklers in; compartment limit out.⇥Travel Distance to Exit LookupTravel distance by occupancy, with all three code corrections.⇔Egress Width CalculatorOccupants times the per-100-persons index gives total width and exit count.◉Concrete Strength Acceptance CalculatorSwitches between statistical and non-statistical criteria automatically.

What this group solves

This group does not calculate — it looks up. Cover varies with exposure class and element type, seismic class depends on intensity, structural form and height together, confinement length depends on seismic class and column dimension, live load depends on occupancy, and fire compartment size depends on building class and whether sprinklers are fitted.

The trap is incomplete conditions. Give an intensity without a structural form and the seismic class cannot be fixed. Give a floor area without saying whether the building is single-storey or sprinklered and the compartment size cannot be checked. So every tool makes its preconditions explicit and refuses to answer until they are all supplied — one extra click is better than a number based on the wrong conditions.

Nothing here is calculated — these are values read from the code. What matters is picking the right row: cover by exposure class and member type, seismic class by intensity, structural form and height, confinement zone by seismic class and joint location, travel distance by occupancy and corridor type. Getting the row wrong is not a numerical deviation, it is a failed statutory review.

Which one for your case

Concrete cover to reinforcement	Concrete Cover Thickness Lookup
Seismic class from intensity, form and height	Seismic Detailing Class Lookup
Column confinement (plastic hinge) zone height	Column Confinement Zone Calculator
Characteristic live loads for floors and roofs	Floor Live Load Lookup
Maximum fire compartment area	Fire Compartment Area Lookup
Travel distance to an exit	Travel Distance to Exit Lookup
Minimum width of stairs and corridors	Egress Width Calculator
Assessment of concrete cube results	Concrete Strength Acceptance Calculator

Where this group goes wrong

Applying a flat 25 mm of cover. It is banded by exposure: class 1 gives 15 mm for slabs and walls but 20 mm for beams and columns; class 2a gives 20/25, class 2b 25/35 and class 3a 30/40. A flat value leaves class 2b elements 10 mm short and fails durability outright.
Reading seismic class from intensity and height only. At intensity 7 and 24 m a frame is class 3 while a shear wall structure is class 4 — one class apart, which is over 30% more column stirrups.
Using one fire compartment figure throughout. Classes 1 and 2 allow 2500 m², class 3 allows 1200 m² and class 4 only 600 m²; basements are capped at 500 m² regardless (doubled with sprinklers). The wrong class is returned by the fire reviewer.
Confusing 'between two exits' with 'dead-end corridor'. Dwellings allow 40 m between exits but only 20 m dead-end; offices 40/22; nurseries 25/20. That is a factor of two, and drawings often show only one figure.

FAQ

What cover should I use?

Per GB 50010 Table 8.2.1, by exposure class and element. Indoor dry conditions give 15 mm for slabs and walls, 20 mm for beams and columns; damp or exposed conditions 20 and 25; the more severe classes go to 25/35 and 30/40. Footings on blinding carry an additional 40 mm requirement.

How is the seismic class determined?

From three inputs together: intensity, structural form and building height. At intensity 7 a frame up to 24 m is class 3 and above 24 m is class 2, while a shear wall structure at the same intensity comes out one class lower. Podiums, towers and basement top restraint have their own adjustment rules on top.

What live load applies to a floor?

Per GB 50009 Table 5.1.1: residential 2.0 kN/m², offices 2.0, classrooms 2.5, corridors and lobbies 2.5, residential stairs 2.0, balconies 2.5, retail 3.5, book stacks 5.0 and plant rooms 7.0. Partition and equipment loads are additional and must not be ignored.

How is cover actually determined?

In three steps: fix the exposure class (class 1 for dry interior, 2a for damp interior or sheltered external, 2b for alternating wet-dry or coastal), then the member type (slab, wall, shell versus beam, column, tie), then adjust for a 100-year design life or demonstrably controlled workmanship. At a footing soffit with blinding, measure from the top of the blinding and take at least 40 mm.

What determines the seismic class?

Three inputs: design intensity, structural type and building height. At intensity 7, a frame structure is class 3 up to 24 m and class 2 above; a shear wall structure is class 4 up to 24 m and class 3 above; frame-shear wall falls between. Irregularities such as transfer, staggered floors and linked towers attract further adjustment.

How tall is the column confinement zone?

At the base of the lowest storey, not less than one third of the clear height. Elsewhere the largest of: the longer column dimension, one sixth of the clear height, and 500 mm. Corner columns of class 1 frames are confined over their full height, and columns on shear walls or transfer columns have stricter rules again.

What is the minimum width of an exit stair?

Dwellings 1.1 m; public buildings 1.0 m per 100 persons with a 1.1 m minimum; hospital wards 1.3 m; assembly buildings such as theatres and arenas 1.4 m and above; high-rise public buildings from 1.2 m. Width is clear width, so handrail projections must be deducted.

Other groups

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

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.