The NSW Building Defects Library for NCC 2022 and 2025: All 40 Defects, in Five Guides

Since September 2020 Building Commission NSW has audited apartment buildings while they are still going up. Its Building Defects Library collects 40 of the defects those audits keep turning up, chosen because they recur, can be seen without testing, and cost far less to fix before anyone moves in.

This series rewrites the Library in five guides, one per building element. Each defect gets its NCC 2025 clause beside the NCC 2022 one the Library was written against, the stage of construction where it is still exposed, and what to check. This page is the index.

In one minute

• The Library lists 40 defects in the five building elements of NSW's Design and Building Practitioners Act 2020: waterproofing (10), fire safety (11), structure (7), building enclosure (6) and services (6).

• Serious defects were reported in 53% of the 520 apartment buildings in the 2025 strata survey, and waterproofing in 44%.

• The Library was written against NCC 2022. Each defect still breaches a requirement under NCC 2025, some under new clause numbers. The biggest changes are new balcony rules in F1D4, Part F3 moving into Part F1, and a rewritten threshold rule for exits.

• Which edition applies depends on your state and a date. NSW, Queensland, South Australia and Tasmania are on NCC 2022 until 1 May 2027, and the Northern Territory has not adopted NCC 2025.

• Every defect has a stage where it is still exposed, and each guide sets out those hold points.

What is the Building Defects Library?

NSW passed two Acts in 2020 that changed how apartment buildings are regulated: the Residential Apartment Buildings (Compliance and Enforcement Powers) Act, which lets the regulator stop work and order defects fixed before an occupation certificate is issued, and the Design and Building Practitioners Act, which brought in registration, compliance declarations and a statutory duty of care. Audits of Class 2, 3 and 9c buildings under construction began in September 2020, and the regulator became Building Commission NSW on 1 December 2023.

The auditors found that a small number of defect types made up a large share of what they detected. The Library gathers those that recur, can be recognised without specialist testing or equipment, and cost much more to fix after occupation. It notes that they may not be the most common defect in each element. Each entry sets out the NCC 2022 provision and the Standard it breaches. The first version was written for certifiers, councils and other industry members; version 1.1 (June 2025) revised the building enclosure section, including the damp-proof course requirements for brickwork.

How common are serious defects in new apartments?

Since 2021, strata managers have been surveyed every two years about serious defects in Class 2 buildings of four or more storeys, a sample chosen to match the six-year statutory warranty for major defects. In the 2025 survey, the first led by Building Commission NSW, with Strata Community Association NSW, 53% of the 520 buildings had at least one serious defect in common property (page 10). Where strata managers knew the cost, serious defects had cost an average of A$215,400 per building (page 4).

Which NCC edition applies to my project?

The Library was written against NCC 2022. NCC 2025 is published nationally but called up by each state on its own date, and the date that decides is usually when the approval is applied for or issued, not when work starts. Your certifier or building surveyor confirms the edition for a project.

State	In force on 7 November 2026	NCC 2025 from	The date that decides
NSW	NCC 2022	1 May 2027	Construction certificate application made
VIC	NCC 2025	1 May 2026	Building permit issued
QLD	NCC 2022	1 May 2027	Building development application approved
SA	NCC 2022	1 May 2027	Building consent application made
WA	NCC 2025 (NCC 2022 may still be used for permit applications made by 30 April 2027)	1 May 2026	Permit application made
TAS	NCC 2022 (NCC 2025 applied from 1 May to 4 June 2026)	1 May 2027	Certificate of likely compliance issued
ACT	Either, chosen per project	Required for approvals from 1 May 2027, unless a DA or works approval was lodged before 1 November 2026	Building approval determined
NT	NCC 2022	Not adopted	Building permit granted

Most of the clauses behind these defects are national, but some states have their own versions of them. Each guide lists the state variations to its own clauses.

The 40 defects by building element

Element	Defects	Reported in 2025	What NCC 2025 changed
Waterproofing	10	44%	NCC 2025 Volume One F1D4 adds balcony rules: a 1:80 fall in the slab itself, an overflow at least 20 mm below the inside slab, a 70 mm step down and a 70 mm hob. Bathroom clauses unchanged.
Fire safety	11	28%	Every clause kept its number. D3D16 now allows a step or ramp at a doorway only where it opens to an external space, C4D10 adds wiring for the stair's pressurisation, and E1D2 also accepts AS 2118.6 or FPAA101H where they apply.
Structure	7	18%	B1D4 still calls up AS 3600:2018 and AS 3700:2018. Structural resistance moved into B1P1, which gains reliability indices a year after adoption; B1D2 now allows for the 10-year deflection of the structural substrates under external waterproofing.
Building enclosure	6	23%	Part F3 moved into Part F1 (F3D4 is now F1D14, F3D5 is F1D15, F1D6 is F1D8). For these defects the rules read the same; AS 1530.1 moves to its 2024 edition.
Services	6	15%	The clause numbers stay the same. F6D6 adds natural ventilation to AS 1668.4, AS 1668.2 moves to its 2024 edition, and E2D12 no longer names one clause of AS 1668.1.

Waterproofing: 10 defects

Five defects on balconies and roofs, where AS 4654.2 governs the membrane, and five in bathrooms, where AS 3740 does. NCC 2025 renumbered Part F1 and wrote balcony falls, overflows, step downs and hobs into the Code; the bathroom clauses read the same in both editions. Read Part 1: waterproofing.

1. The membrane stops at the outlet
2. The membrane is not turned into the overflow
3. Water ponds on the balcony or roof
4. The surface is not ready for the membrane
5. The membrane is not terminated at the sliding door
6. Water ponds on the bathroom floor
7. Water ponds in the shower
8. No waterstop at the doorway
9. The floor waste flange sits proud
10. The fillet or bond breaker at the wall is wrong

Fire safety: 11 defects

Two defects in fire-rated walls and service penetrations, three in fire doors under AS 1905.1, four in the fire-isolated exits and stairs (services, thresholds, headroom, risers and goings), and two at the hydrants under AS 2419.1. Fire door gaps change when the floor finish goes down, so they are measured after it. Read Part 2: fire safety.

1. The fire-rated wall stops at the ceiling
2. Services pass through without tested protection
3. The fire door does not close and latch by itself
4. The gaps around the fire door are too big
5. The fire door frame is hollow
6. Services run through the fire-isolated stair
7. There is a step at the stair door
8. There is not enough headroom in the exit
9. Risers and goings are not constant
10. The hydrant outlet points down too steeply
11. Nothing is kept clear in front of the hydrant

Structure: 7 defects

One masonry defect, an opening with no lintel, and six in concrete: cover and honeycombing, rain on a fresh pour, cut reinforcement, movement joints, slab-on-ground joints and debris. The site checks are the same in both editions; joints are checked against the approved structural plans. Read Part 3: structure.

1. No lintel over an opening in masonry
2. Too little cover, exposed reinforcement or honeycombing
3. Concrete placed in the rain
4. Reinforcement cut or damaged
5. A movement joint that cannot move
6. A slab on ground without the joints on the plans
7. Debris cast into the concrete

Building enclosure: 6 defects

Four masonry workmanship defects under AS 3700 (damp-proof courses, weepholes and flashings), one at windows and doors under AS 2047, and combustible cladding under C2D10, with the NSW ban on aluminium composite panels. Read Part 4: building enclosure.

1. The damp-proof course stops short of the face
2. Weepholes are missing or too far apart
3. A window or door has no flashing, or the wrong one
4. Weepholes sit below the level outside
5. The facade is combustible
6. A flashing does not project far enough

Services: 6 defects

All six are ventilation and ductwork: a car park jet fan blowing onto the sprinklers or detectors, a room with no ventilation, and four duct defects under AS 4254.1 and AS 4254.2. The survey's key services figure also covers plumbing, electrical services, acoustics and lifts. Read Part 5: services.

1. A jet fan blows onto the sprinklers or detectors
2. A room has no ventilation
3. A flexible duct joint is not airtight
4. The flexible duct has no compliance label
5. Rigid duct joints are not sealed
6. A rigid duct is not properly supported

What does this series add to the Library?

• Both editions. The NCC 2025 clause sits beside the NCC 2022 one for every defect, with the state variations that affect it.

• When to catch it. Each guide maps its defects to the inspection where they are still visible, before they are covered up.

• Drawings and a calculator. Each guide has drawings made for it, with the defects numbered, and a small calculator for one of the checks.

How can AEC Assistant help?

AEC Assistant works from the edition and state of your project, and cites the clauses it relies on.

• Before construction: upload the drawings to a project and ask it to review the details behind these defects. It marks each issue it finds on the sheet, with the clause.

• For the site: it builds an inspection and test plan from your specification, with hold points like the ones in each guide.

• When a defect is found: it turns site photos and notes into a defect register and drafts the direction notice or defect letter, citing the clause for your edition.

Where to read the source

• Building Defects Library, Building Commission NSW, v1.1, June 2025 (written against NCC 2022)

• 2025 Strata Defects Report, Building Commission NSW with Strata Community Association NSW, November 2025

• NCC 2025 and NCC 2022 with Amendment 2, from the ABCB