The 7 Structural Defects NSW Keeps Finding in New Apartments (NCC 2022 and 2025)
Building Commission NSW lists seven structural defects its auditors keep finding on apartment sites, from a missing lintel to cut reinforcement. Here is each one with its NCC 2025 and NCC 2022 clause and when to catch it, plus a lintel bearing calculator.
Since September 2020, the NSW building regulator, now Building Commission NSW, has audited apartment buildings while they are still under construction, and its auditors keep recording the same few defects. The Building Defects Library is the list: 40 defects across the five building elements of the Design and Building Practitioners Act, each tied to the clause it breaches.
This series works through the Library one element at a time and adds what it leaves out: the NCC 2025 clause beside the NCC 2022 one it was written against, the stage of work when each defect is still easy to see, and what to keep as evidence. This is part 3 of five, on structure: one defect in masonry and six in concrete.
In one minute
Structural defects were reported in 18% of the 520 buildings in the 2025 strata survey, and more surface as buildings age: in buildings registered in 2018 the share went from 17% to 31% in two years.
The Library lists seven. One is masonry over an opening with no lintel; the other six are in concrete: cover and honeycombing, rain on a fresh pour, cut reinforcement, movement joints, slab-on-ground joints and debris.
The route to the Standards is the same in both editions. B1D4 calls up AS 3700:2018 for masonry and AS 3600:2018 for concrete in NCC 2022 and NCC 2025.
NCC 2025 rewrote the Performance Requirement, not the site checks. Structural resistance moved into B1P1, which gains minimum reliability indices a year after adoption. NSW keeps its own version.
For joints, the drawings are the test. AS 3600 says what a joint must do, not where it goes, so movement joints and slab joints are checked against the approved structural plans.
How common are structural defects in new apartments?
Every two years, strata managers are surveyed about serious defects in the common property of 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 of 520 buildings, by Building Commission NSW with Strata Community Association NSW, structural defects were reported in 18%, up from 15% in 2023 (page 12).
The pattern is age. Buildings registered from 2018 to 2021 reported structural defects at twice the rate of those from 2022 to 2024, 21% against 10% (page 2), and among buildings registered in 2018 the share rose from 17% to 31% between the two surveys, a significant increase (pages 12 and 13). The report suggests part of it may be a detection lag: serious defects can take years to show, so low rates in the newest buildings may not last.
Which NCC edition applies to my project?
The Library was written against NCC 2022. NCC 2025 is published nationally, then adopted 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. The certifier or building surveyor confirms which edition a project falls under.
| 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 |
The structural clauses vary in a few places. Queensland and the Northern Territory have their own versions of B1D4 in both editions, and Western Australia had one in NCC 2022, but the lines that call up AS 3700 and AS 3600 read the same in every version. Under NCC 2025, NSW replaces B1P1 with a version that leaves out the new reliability indices, and keeps structural resistance as a separate NSW B1P4.
What changed for structure in NCC 2025?
The Deemed-to-Satisfy route is untouched: B1D4 calls up the same two Standards, at the same editions, in both editions. What NCC 2025 rewrote is the Performance Requirement above it.
| Requirement | NCC 2022 | NCC 2025 |
|---|---|---|
| Structural reliability | B1P1 | B1P1, adding minimum reliability indices as B1P1(2), in force a year after adoption |
| Structural resistance and material properties | B1P2 | A shorter version is now B1P1(4); NSW keeps the full text as NSW B1P4 |
| Actions to design for, including creep, shrinkage and thermal effects | B1P1(2) | B1P1(3); in NSW, NSW B1P1(2) |
| Resistance greater than the most critical action effect | B1D2 | B1D2, now also allowing for the expected 10-year deflection of structural substrates in Part F1 |
| Masonry to AS 3700, concrete to AS 3600 | B1D4(1)(a), (1)(b)(i) | B1D4(1)(a), (1)(b)(i) |
| Editions called up | AS 3700:2018; AS 3600:2018 with Amendments 1 and 2 | The same |
For a building designed to AS 3600 and AS 3700, nothing checked on site moves: B1D1 still deems the Performance Requirements met by B1D2 to B1D6, and a Performance Solution for concrete or masonry against the new indices must show it is at least equivalent to the Deemed-to-Satisfy Provisions. That rule is A2G2(5) nationally and a Limitation to A2G2 in Victoria, is not in NSW's version, and takes effect a year after adoption. The one new design rule links to part 1: B1D2(1)(b) allows for the expected 10-year deflection of the structural substrates in Part F1, such as the balcony slabs that must now hold a 1:80 fall themselves.
The seven structural defects
Each one breaks AS 3700 or AS 3600, which both editions call up for masonry and concrete, or AS 1379, which AS 3600 calls up for the concrete itself. All seven can be seen without specialist testing, one of the reasons the Library chose them.
1. No lintel over an opening in masonry
Unreinforced masonry is laid straight over a door, window or service opening with nothing to carry it, or on a lintel too short to sit on the masonry at each end. The courses over the gap crack and can drop.
| Both editions | B1P1; B1D4(1)(a): masonry to AS 3700 |
| Standard | AS 3700 cl 4.13: masonry over an opening is carried by an arch, a lintel or a frame; a lintel bears at least 100 mm each side for an opening up to 1000 mm wide and 150 mm for a wider one, and deflects no more than span/360 or 10 mm, whichever is less |
| Catch it | As the masonry reaches the head of each opening. Check every lintel against the lintel schedule and measure its bearing at both ends before the next course goes on. |
2. Too little cover, exposed reinforcement or honeycombing
Bars sit too close to the face or show through it, or the concrete did not fill the form and left voids and bare aggregate. Cover is what protects the steel from corrosion and fire, and a honeycombed member is weaker and lets water in.
| Both editions | B1P1; B1D4(1)(b)(i): concrete to AS 3600 |
| Standard | AS 3600 cl 4.10: the largest cover needed for placing, corrosion protection (by exposure classification and concrete strength), aggressive soils and fire; cl 17.5.3: in beams, slabs, columns and walls, no more than 5 mm under the specified cover; cl 17.1.3: compacted to fill the form around the steel; cl 17.1.7: honeycombed concrete is liable to rejection unless calculation or testing shows the member is not impaired |
| Catch it | Before the pour, measure cover at the chairs against the structural drawings, with no tie wire left in the cover (cl 17.2.5). After stripping, photograph anything found before it is patched: a patch hides what the engineer needs to see. |
3. Concrete placed in the rain
The pour goes ahead in rain, or rain arrives before the concrete has set and nobody covers it. Water on fresh concrete washes cement out of the surface and leaves weak, porous concrete in the cover that protects the steel.
| Both editions | B1P1; B1D4(1)(b)(i): concrete to AS 3600 |
| Standard | AS 3600 cl 17.1.5.2: fresh concrete protected from rain, running water, freezing and drying until it hardens, then from freezing and drying through the first curing; cl 17.1.5.1: cured continuously for as long as the design needs, as the project specification sets out |
| Catch it | The day before the pour: check the forecast and that covers are on site. Record the weather on the pour record. |
4. Reinforcement cut or damaged
A core hole, chase or saw cut for a service goes through a bar, or a bar in the way is cut on site. AS 3600 works out a member's bending strength on the basis that the concrete carries no tension at all, so a cut bar means lost strength, however sound the concrete looks.
| Both editions | B1P1; B1D4(1)(b)(i): concrete to AS 3600 |
| Standard | AS 3600 cl 8.1.2(b): bending strength is calculated with the concrete taking no tension, for beams and, through cl 9.1.1, for slabs; cl 10.6.1(b): the same for columns |
| Catch it | Before coring or chasing: scan the element and get the engineer's approval for the location, or, better, set sleeves before the pour. If a bar is cut, get the engineer's assessment and repair in writing. |
5. A movement joint that cannot move
A joint in a suspended slab is built in the wrong place, with the wrong dowels or sleeves, grouted too early or packed with debris, so the slab cannot move as designed. A permanent joint moves for the life of the building; a temporary one is left free while the slab shrinks, then closed.
| NCC 2025 | B1P1, whose actions include differential movement, creep, shrinkage and thermal effects (B1P1(3)(j) to (l); NSW B1P1(2)(j) to (l) and NSW B1P4); B1D4(1)(b)(i) |
| NCC 2022 | B1P1(2)(j) to (l), the same actions; B1P2: resistance must allow for restrained movement from temperature, moisture, shrinkage and creep; B1D4(1)(b)(i) |
| Standard | AS 3600 cl 19.1.1 and 19.1.3: a movement joint is designed and built to control movement or cracking, or to separate members, without loss of capacity or serviceability; cl 19.1.4: sealed or detailed to keep dirt and incompressible material out. The Standard does not say where joints go: the approved structural drawings do. |
| Catch it | Before the pour: check each joint's position, dowels and sleeves against the structural drawings. Close a temporary joint only when the engineer releases it, and record the date. |
6. A slab on ground without the joints on the plans
A slab on ground is poured without the saw cuts or isolation joints the structural drawings show, or with them somewhere else. A saw cut does not stop a slab cracking; it decides where the crack forms, in a straight line the designer chose. Isolation joints let the slab move separately from columns, walls and pits.
| Both editions | B1P1; B1D4(1)(b)(i): concrete to AS 3600 |
| Standard | AS 3600 cl 21.2: the design of a slab on ground and its joints considers, among other things, movement at joints, crack control and shrinkage warping. It sets no joint layout: the approved structural drawings do. |
| Catch it | Before the pour, check the joint layout on the drawings and agree when the saw cuts will be made: a cut made after the slab has cracked on its own does nothing. |
Not every slab needs them: the Library itself warns that a watertight slab, or one designed to span over weak ground, may have none. Check the drawings before calling it a defect.
7. Debris cast into the concrete
Offcuts, packaging, timber, tie wire or rubbish left in the forms, or foreign matter in a load, ends up inside the member, leaving voids and weak spots where no one can see them.
| Both editions | B1P1; B1D4(1)(b)(i): AS 3600, which requires concrete made and supplied to AS 1379 (cl 17.1.1 and 17.1.2) |
| Standard | AS 1379 cl 2.6, the clause the Library cites, which bars mixing incompatible materials in one batch; AS 3600 cl 17.1.3(c): placed to form one monolithic mass between the planned joints |
| Catch it | Just before the pour: clean out the forms, tie-wire offcuts included (AS 3600 cl 17.2.5 note), and refuse a load with foreign matter in it. |
How much bearing does a lintel need?
Enter the clear width of an opening in unreinforced masonry. The calculator gives the end bearing AS 3700 requires on each side and the shortest lintel that provides it, the same under NCC 2022 and NCC 2025. For a 1200 mm opening, that is 150 mm each side and a lintel at least 1500 mm long.
When should each defect be caught?
The Library also chose defects that cost far less to fix during construction than after people move in. Each has a moment when it is still in plain view:
| Stage | Check | Defects |
|---|---|---|
| Reinforcement inspection, before the pour | Cover at the chairs, bars complete, sleeves for services, movement joints and slab joints set out to the drawings, forms clean | 2, 4, 5, 6, 7 |
| The day of the pour | Forecast and covers, delivery dockets, compaction around congested steel | 2, 3, 7 |
| After the pour | Saw cuts at the agreed time, curing, temporary joints closed only when released | 3, 5, 6 |
| After stripping, before finishes | Faces and soffits for honeycombing and exposed steel, photographed before any patching | 2 |
| As the masonry rises | A lintel over every opening, its size and its bearing at both ends | 1 |
| Before coring or chasing | A scan, and the engineer's approval for the location | 4 |
How can AEC Assistant help?
AEC Assistant works from the edition and state of your project, and cites the clauses it relies on.
Before the pour: upload the structural and architectural drawings to a project and ask it to review them for the items above, such as a lintel scheduled for every masonry opening and joints shown on the slab plans. 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 above.
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 Volume One, Part B1 and A2G2, and NCC 2022 Volume One with Amendment 2, from the ABCB
AS 3700:2018, AS 3600:2018 with Amendments 1 and 2, and AS 1379 (the Library cites the 2007 edition; clause 2.6 reads the same in AS 1379:2026), from Standards Australia
This is part 3 of five in our rewrite of the Building Defects Library. The others cover waterproofing, fire safety, building enclosure and services, and the series index lists all 40 defects.
Questions this guide answers
Which structural defects does the NSW regulator keep finding?
Building Commission NSW's Building Defects Library lists seven that its auditors find often on apartment sites: unreinforced masonry over an opening with no lintel; too little cover, exposed reinforcement or honeycombing; concrete placed in the rain; reinforcement cut or damaged; a movement joint in a suspended slab not built as designed; a slab on ground without the saw-cut or isolation joints on the approved plans; and debris cast into the concrete. Structural defects were reported in 18% of the 520 buildings in the 2025 strata survey.
Did NCC 2025 change the structural rules for concrete and masonry?
Not for anything checked on site. In both editions B1D4(1) calls up AS 3700:2018 for masonry and AS 3600:2018 for concrete. NCC 2025 rewrote the Performance Requirement: structural resistance, B1P2 in NCC 2022, is now part of B1P1, and B1P1(2) adds minimum reliability indices that take effect a year after NCC 2025 is adopted. Under NCC 2025, NSW keeps its own B1P1 without the indices, and structural resistance as NSW B1P4.
How much bearing does a lintel need?
Under AS 3700:2018 clause 4.13, at least 100 mm on each side for an opening up to 1000 mm wide and 150 mm for a wider one, so a lintel over a 1200 mm opening is at least 1500 mm long. The same clause limits its deflection to span/360 or 10 mm, whichever is less. NCC 2022 and NCC 2025 both call up AS 3700 through B1D4(1)(a).
Is honeycombed concrete a defect?
AS 3600 clause 17.1.7 makes honeycombed concrete liable to rejection. It can still be accepted if calculation or testing shows the member's structural adequacy and intended use are not impaired, which is for the structural engineer to assess, so photograph it before anyone patches it.
Does every slab on ground need saw-cut joints?
No. The approved structural drawings decide. AS 3600 clause 21.2 asks the designer to consider crack control, shrinkage warping and movement at joints, but sets no joint layout, and the Library itself warns that a watertight slab, or one designed to span over weak ground, may have none. Where the drawings show saw cuts or isolation joints, they must be built.
