Code and compliance

20 October 2026

Accessible Toilet Requirements in Australia: When the NCC Requires One, How Many, Ambulant Toilets and the AS 1428.1 Layout (2025 Guide)

Under NCC 2025 a Class 5 to 9 building that must have toilets needs an accessible unisex toilet on every storey with toilets (a small-building concession aside), at not less than half the banks where a storey has more than one, and an ambulant toilet for each sex at a bank where the accessible one has other toilets beside it (F4D5, F4D6). This guide covers when one is required, the count for each class, small cafés and small buildings, and the AS 1428.1:2021 layout, with a checker that counts them.

5 October 2026

NCC Building Classes Explained: Class 1 to 10, Every Sub-Class, Mixed Use and the 10% Rule (2025 Guide)

The NCC sorts every building by its use into Classes 1 to 10. This guide sets out each class and sub-class from Part A6, the tests that separate a Class 1a townhouse from a Class 2 apartment and a Class 1b guest house from a Class 3, how a building with several uses is classified, the 10% minor-use rule and its exceptions, and what the class decides in the rest of the Code. With a class finder.

5 October 2026

Type A, B and C Construction in the NCC: How Rise in Storeys and Class Set the Type, Effective Height, and What Each Type Changes (2025 Guide)

Table C2D2 of NCC Volume One sets a building's Type of construction from two facts: its class and its rise in storeys. This guide explains how C2D3 counts storeys on a sloping site, with basements, rooftop plant, mezzanines and tall industrial storeys, how effective height differs, the two-storey concession, and what Type A, B or C changes beyond FRLs. A section builder counts the storeys and gives the Type.

5 October 2026

Wind Classification for Houses: AS 4055 N1, N2, N3 and Cyclonic C1 to C4, How Terrain, Shielding and Topography Set the Class, and a Free Calculator (2025 Guide)

A house site's wind classification, N1 to N6 or C1 to C4 in cyclonic regions, is read from AS 4055:2021 Table 2.2 using four site conditions: the wind region, the terrain category within 500 m, the topographic class and the shielding class. This guide explains how each is found, with its clause, where the NCC uses the class, and a calculator that applies Table 2.2 to your site.

5 October 2026

Class 10a Buildings: NCC Rules for Sheds, Garages and Carports, and Fire Separation from the Boundary (2025 Guide)

What Class 10a, 10b and 10c mean in the NCC, which parts of the Code apply to a shed, garage or carport, and when a Class 10a near a boundary or another building needs a fire-rated wall under Housing Provisions 9.2.4 to 9.2.8. Every protection method the Code accepts, the open-carport test, garages under dwellings and the South Australian variations, with a checker that draws your site.

5 October 2026

Livable Housing Design Standard: The NCC 2025 Checklist for Step-Free Paths, 820 mm Doors, Toilets, Showers and Grabrail Reinforcement (2025 Guide)

What the ABCB Standard for Livable Housing Design asks of a new house or apartment: a step-free path no steeper than 1:14 with no more than 9 m of ramping at 1:14, an 820 mm entrance door with a 1200 mm landing, 820 mm internal doors and 1000 mm corridors, an entry-level toilet with a 1200 × 900 mm clear space, a hobless shower and walls reinforced for grabrails. Every clause, the state variations printed in NCC 2025, a printable checklist and a checker.

5 October 2026

Termite Protection Requirements: NCC 2025 Part 3.4, AS 3660.1, Slab Edge Exposure, Subfloor Clearance and the Durable Notice (2025 Guide)

A termite management system is required where a Class 1 or 10 building is in an area where subterranean termites are a known risk and a primary building element is susceptible to attack. This guide sets out the materials the NCC treats as not subject to attack, the options in Housing Provisions Table 3.4.2, the 75 mm exposed slab edge and 400 mm subfloor clearance of AS 3660.1, the durable notice, the Queensland and Northern Territory variations and what Volume One requires for Class 2 to 9 buildings.

21 September 2026

Luminance Contrast Calculator: The AS 1428.1 30% Rule, LRV and the Bowman-Sapolinski Equation (2025 Guide)

Where AS 1428.1:2021 asks for 30% luminance contrast (doorways, stair nosing strips, the line on frameless glazing, toilet seats), how the Bowman-Sapolinski equation in Appendix B turns two light reflectance values into a contrast figure, why LRV 40 against 70 fails while LRV 5 against 30 passes, the 45% and 60% for tactile indicators, and a calculator that runs the equation for your pair.

21 September 2026

NCC D2D18 Explained: Number of Persons Accommodated and Table D2D18 Area per Person (2025 Guide)

How NCC Volume One D2D18 sets the number of persons a storey, room or mezzanine is assessed for: the floor area of each part divided by the Table D2D18 figure for its use, with lifts, stairs, corridors, lobbies, ducts and sanitary compartments left out; or a seating count; or another suitable assessment. The full table, the NSW version, a worked office example, the clauses that then use the number, and a calculator that runs the method.

21 September 2026

NCC D3D14 Goings and Risers: Table D3D14 Stair Dimensions Explained (2025 Guide)

Clause D3D14 of NCC Volume One sets every stair dimension for a Class 2 to 9 building: 2 to 18 risers a flight, Table D3D14's riser, going and 2R + G limits, the 5 mm and 10 mm constancy rule, the 125 mm sphere, slip resistance, solid treads, the Class 9b 36-riser rule and winders. Every sub-clause explained, with the NSW variation, the Housing Provisions equivalent and a checker for your flight.

21 September 2026

NCC D3D17 Barriers to Prevent Falls: When a Balustrade Is Required (2025 Guide)

Clause D3D17 of NCC Volume One is the trigger for a balustrade: a continuous barrier along the side of a stair, ramp, floor, balcony, mezzanine, accessible roof or path where the trafficable surface is 1 m or more above the surface beneath. The four locations, the four exclusions, the construction rules in D3D18 to D3D21 it calls up, the NSW variation, the Housing Provisions equivalent for a house, and a checker for your edge.

21 September 2026

NCC D3D22 Handrails: The Clause Explained Sub-clause by Sub-clause (2025 Guide)

Clause D3D22 of NCC Volume One sets the handrail rule for every stair and ramp in a Class 2 to 9 building: one side, both sides at 2 m wide, the top not less than 865 mm above the nosings, continuous between landings, the second lower rail in primary schools and early childhood centres, AS 1428.1 in an accessible exit, the health-care and aged care corridor rails, and the separate rules for a stair inside an apartment. Every sub-clause explained.

21 September 2026

Ramp Requirements in Australia: NCC and AS 1428.1 Gradients, Landings, Handrails and a Free Ramp Calculator (2025 Guide)

The gradient an accessible ramp may have (1:14), where it becomes a walkway (1:20), how far it can run before a landing (9 m), the 1000 mm width, the 1:40 crossfall, handrails both sides with 300 mm extensions and the 65 mm kerb, with the step, threshold and kerb ramps that sit beside them. Every figure from AS 1428.1:2021 and the NCC clause that calls it up, and a calculator that checks your rise and length.

21 September 2026

NCC Sanitary Facilities: How Many Toilets a Building Needs, Table F4D4 and a Free Calculator (2025 Guide)

How many closet pans, urinals and washbasins a Class 3 to 9 building needs under NCC Volume One Part F4: count the people, split them by sex, read the band in the right F4D4 table and round any part of the next band up. The tables for offices, factories, shops, restaurants and schools, the accessible and ambulant compartments that sit on top, the unisex and all-gender options, the state variations, and a calculator that draws the bank of fixtures for your numbers.

21 September 2026

Gutter and Downpipe Sizing in Australia: The NCC Tables, AS/NZS 3500.3 and a Free Calculator (2025 Guide)

How eaves gutters, downpipes and overflow measures are sized under NCC 2025: the 5-minute rainfall intensity for your locality, the gutter type from Table 7.4.3a, the 12 m per downpipe rule and the overflow volume the gutter must shed in a 1% AEP storm. Every table, the Code's own worked example, and a calculator that runs the method for your roof.

18 September 2026

NCC Fire-Resistant Building Elements: How an FRL Is Proved, the Deemed Thickness Tables for Walls, Columns and Beams, and What a House Needs (2025 Guide)

A wall, column, floor or beam is a fire-resistant building element when it holds a fire-resistance level, and NCC Volume Two Specification 1 sets the six ways to prove one: the deemed thickness tables, a tested prototype, an assessment of a near-identical element, a design to the structural standard, a calculation, or the fire-protected timber route. This guide walks through each with the clause, reproduces the deemed tables for masonry, concrete and gypsum walls and for protected steel, explains the Specification 2 detailing rules that come with them, shows where a house needs one, and includes a finder for steel column and beam protection.

16 September 2026

NCC Fire Resistance Levels (FRL) Explained: What 90/60/30 Means, Type A, B and C Construction, and the FRL Your Wall Needs (2025 Guide)

An FRL is three numbers in minutes: structural adequacy, integrity and insulation, in that order, from the AS 1530.4 furnace test. Which FRL a wall, column, floor or roof needs comes from the building's class, its rise in storeys (which sets Type A, B or C construction) and, for external walls, its distance from a boundary or another building. This guide explains each step with the clause, and the finder below reads the Specification 5 tables for your element.

10 September 2026

NCC Handrail Requirements: Height, Where They Are Required, Extensions and Landings (2025 Guide)

The NCC handrail rule for a house is one rail, on one side, with its top at least 865 mm above the nosings. A commercial stair adds a second rail once it is 2 m wide, and an accessible stair adds a 1000 mm maximum, both sides, a 30 to 52 mm grip and 300 mm extensions. This guide sets out each rule with its clause, and the checker below draws the rail for your stair.

9 September 2026

NCC Insulation Requirements: R-Values for Roofs, Walls and Floors by Climate Zone (2025 Guide)

The minimum insulation R-value for a house ceiling, wall or floor is read from the climate-zone tables in Part 13.2 of the ABCB Housing Provisions. This guide gives the headline NCC 2025 figures for the common cases in all eight zones, plus the thermal bridging, reflective foil, solar absorptance, edge-reduction and condensation rules around them.

8 September 2026

Fire-Rated Walls for Houses: NCC 900 mm Boundary Rule, FRL 60/60/60 and Party Walls (2025 Guide)

When a house wall must be fire-rated under the NCC: the 900 mm boundary and 1.8 m building-to-building rules in Housing Provisions 9.2.1, what FRL 60/60/60 means, openings and eaves near the boundary, separating walls to 9.3.1, service penetrations, garage exemptions, and the SA, NSW and WA variations.

7 September 2026

BAL Ratings Explained: What Each Bushfire Attack Level Means, How a BAL Is Calculated under AS 3959, and a Free BAL Calculator (2025 Guide)

A BAL rating, or Bushfire Attack Level, grades how much ember attack, radiant heat and flame a building on bushfire prone land could face, in six levels from BAL-LOW to BAL-FZ. This guide explains what each level means, how AS 3959:2018 works it out from the fire danger index, vegetation, distance and slope, what each level requires of walls, windows, roofs and decks, where NCC 2025's state variations change the rules, and a calculator that estimates the level for a site.

6 September 2026

NCC Balustrade Requirements: Heights, Gaps, Climbability, Glass and Wire Barriers (2025 Guide)

Every NCC balustrade figure in one place: the 1 m fall trigger, 1 m and 865 mm heights, the 125 mm sphere and 40 mm face gap, the 150 to 760 mm climbability zone above 4 m, wire barrier tables, AS 1288 glass rules and the 2 m and 4 m openable window limits.

5 September 2026

NCC Ceiling Heights: Minimum Room Heights for Houses and Commercial Buildings (2025 Guide)

Every NCC minimum ceiling height in one place: 2.4 m habitable rooms, 2.1 m kitchens, bathrooms and garages, 2.0 m over stairs, the two-thirds rule for raked ceilings and attics, and the Volume One figures for apartments, offices, schools and hospitals.

4 September 2026

NCC Climate Zones Explained: The 8 Zones, How to Find Yours, and What Changes Between Them (2025)

The eight NCC climate zones explained: what each one means, how to find the zone for any address (Sydney is two zones), why NCC and NatHERS zones differ, and what NCC 2025 changes between them for insulation, roof colour, wall membranes and the drained cavity now mandatory in zones 6, 7 and 8 (outside NSW and Tasmania).

2 September 2026

NCC Stair Requirements: Risers, Goings, Handrails and Balustrades (2025 Guide)

Every NCC 2025 stair dimension for a house and a commercial building, with the clause behind each figure: riser 115 to 190 mm, going 240 to 355 mm, 2R + G between 550 and 700, 865 mm handrails, 1 m barriers and the 125 mm sphere test. Two diagrams and a free calculator.

1 September 2026

NCC 2025: What Changed, and When Your State Adopts It

NCC 2025 became available for adoption on 1 May 2026. Four months on, it is still not the code most Australian projects are assessed against. Who is on it, who is not, and what changed at clause level.

1 September 2026

Waterproof vs Water-Resistant: The AS 3740:2021 Materials Lists and the Compatibility Chain

AS 3740:2021 sorts every wet-area material into waterproof or water-resistant, in Clause 3.3. The lists as a working reference, the NCC clauses that decide which label applies, and the compatibility chain in Appendix E that most failures break.

1 September 2026

AS 3740:2021 Explained: Scope, Changes from 2010, and How the NCC Calls It Up

AS 3740:2021 is the edition NCC 2025 calls up in its wet-area provisions. What it covers, what changed from 2010 with clause references, which NCC clause calls it up for your building class, and the numbers to keep at hand.

4 August 2025

The Block 2025 Bathroom Week: What the Reveals Show About AS 3740 and the Housing Provisions

The Block 2025 bathroom week: adhesive failures, high vanities and an unfinished room. Every one of those maps to a clause, and the clauses for a Class 1 house are not the ones most articles cite. A verified checklist for waterproofing, ventilation, livable housing, electrical and plumbing.

29 July 2025

NCC 2022 Amendment 2: Every Change, and What to Re-check

NCC 2022 Amendment 2 took effect on 29 July 2025. It references AS 1428.1:2021 and rewrites D3D22, D4D4 and Volume Three E1D2. Every change, what did not change, and what to re-check.

6 May 2025

AS/NZS 3500 Plumbing and Drainage Standards Explained: Parts 1 to 4, Where NCC 2025 Calls Them Up and What Changed (2025 Guide)

AS/NZS 3500 is the plumbing and drainage Standard series: Part 1 water services, Part 2 sanitary plumbing and drainage, Part 3 stormwater drainage and Part 4 heated water services, with Part 0 as the glossary. What each Part covers, which edition is current, where NCC 2025 calls it up, and what changed in the 2025 editions clause by clause, with the free calculators that apply them.