The 6 Building Enclosure Defects NSW Keeps Finding in New Apartments (NCC 2022 and 2025)
Building Commission NSW lists six building enclosure defects its auditors keep finding on apartment sites, from damp-proof courses and weepholes to flashings and cladding. Here is each one with its NCC 2025 and NCC 2022 clause and when to catch it, plus a weephole calculator.
When Building Commission NSW inspects apartment buildings under construction, the same faults in the building's skin keep turning up. Its Building Defects Library lists six, in the brick walls, the flashings around windows and the facade itself, each with the clauses it breaches.
This is part 4 of five. The series takes the Library one building element at a time and adds the NCC 2025 clause beside the NCC 2022 one it was written against, the point in construction where each defect is still exposed, and what to keep as evidence. It follows the Library's June 2025 revision, which reworked this section and corrected its damp-proof course entry.
In one minute
Building enclosure defects were reported in 23% of the 520 buildings in the 2025 strata survey, up from 19% in 2023, and among buildings registered in 2018 the share rose from 22% to 31% as they aged.
The Library lists six: a damp-proof course that stops short of the face, weepholes missing or too far apart, a window or door without flashings, weepholes below the level outside, combustible cladding, and flashings that do not project.
Four are masonry workmanship in AS 3700:2018, which both editions call up. Weepholes go in the first course over every flashing, no more than 1200 mm apart.
NCC 2025 renumbered the clauses; for these defects the rules read the same. Part F3 moved into Part F1, so F3D4 is now F1D14 and F3D5 is F1D15. C2D10, the non-combustible external wall rule, is unchanged.
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.
How common are building enclosure defects?
The strata survey counts building enclosure as its own type of serious defect, covering the facade, doors and windows. Strata managers reported one in 23% of the 520 buildings in the 2025 survey, up from 19% of 642 in 2023 (Figure 4, page 12). It also grew as buildings aged: among buildings registered in 2018, the share rose from 22% in the 2023 survey to 31% in 2025 (Figure 6, page 13).
Non-compliant cladding went the other way, from 8% to 2% of all buildings. None was reported in buildings registered from 2020 onwards, against 6% of those registered in 2018 (page 12). The report says that may be due in part to Project Remediate, the NSW program that replaced combustible cladding on eligible apartment buildings and closed in mid-2024 (page 21), and to wider awareness of the problem.
The report's case studies show how late some of these defects surface. In one building of about 110 apartments, the building enclosure defect was non-compliant bathroom windows; its other defects included fibre cement facade sheeting that was not applied correctly and let water in, which the report files as structural. The owners found the facade problem through their own expert report, not the inspections under the strata building bond scheme (page 44).
Which NCC edition applies to my project?
The Library is 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 |
Of the clauses in this guide, South Australia replaces the damp-proof course materials clause (F1D6(2) in NCC 2022, F1D8(2) in NCC 2025) and inserts its own rising damp Performance Requirement (F1P4 in NCC 2022, F1P2 in NCC 2025). Queensland and the Northern Territory have their own versions of B1D4, and so did Western Australia in NCC 2022. Under NCC 2025, NSW also keeps the NCC 2022 wording of "non-combustible", without NCC 2025's reference to an Accredited Testing Laboratory, which a note defers until the next edition in any case. The glazing and wall cladding clauses (F3D4 and F3D5; F1D14 and F1D15), and C2D10 and C2D14, have no state variations.
What changed for external walls in NCC 2025?
NCC 2025 folded Part F3, roof and wall cladding, into Part F1, whose rainwater Performance Requirement, F1P1, is now the Part's only national one. It sets the rain a building must cope with by annual exceedance probability, and its note names external walls and the openings around windows and doors among the building elements it applies to. Rising damp keeps only a Functional Statement, F1F2, with damp-proofing among the Deemed-to-Satisfy clauses F1D1(1) lists; South Australia inserts its own Performance Requirement, F1P2. The Deemed-to-Satisfy clauses moved but, for an apartment building, read the same. The fire clauses did not move.
| Requirement | NCC 2022 | NCC 2025 |
|---|---|---|
| Keeping rain out of roofs and external walls | F3P1 | F1P1 |
| Moisture from the ground | F1P4 | No national Performance Requirement: Functional Statement F1F2, with F1D8 among the Deemed-to-Satisfy clauses in F1D1(1); South Australia inserts its own F1P2 |
| Damp-proofing and damp-proof courses | F1D6 | F1D8 |
| Glazed assemblies to AS 2047 | F3D4 | F1D14 |
| Wall cladding: masonry to AS 3700 | F3D5 | F1D15 |
| Masonry structure to AS 3700 | B1D4 | B1D4 |
| Non-combustible external walls | C2D10 | C2D10, unchanged |
| Ancillary elements | C2D14 | C2D14, unchanged |
| Combustibility test | AS 1530.1:1994 | AS 1530.1:2024; reports on the 1994 edition issued before the change remain valid |
The six building enclosure defects
Four of the six are masonry workmanship. Both editions call up AS 3700:2018 for masonry twice: as structure under B1D4, the clause the Library cites, and as wall cladding that keeps the weather out, under F3D5 in NCC 2022 and F1D15 in NCC 2025. The window flashings are AS 2047, and combustible cladding is a fire rule.
1. The damp-proof course stops short of the face
The damp-proof course (DPC) stops short of the face of the brickwork instead of projecting past it, so moisture can track around its edge and mortar or render can bridge it.
| NCC 2025 | F1D8(1)(b): moisture from the ground kept from the walls above the damp-proof course; F1D8(2): the DPC to AS/NZS 2904, or impervious sheet to AS 3660.1; B1D4 and F1D15(1)(a): masonry to AS 3700 |
| NCC 2022 | F1D6(1)(b) and F1D6(2); B1D4 and F3D5(1)(a) |
| Standard | AS 3700 cl 12.4.16: a sheet DPC laid to stick out past both faces as the wall goes up, then trimmed flush or folded down once the wall is finished, and never covered by render; cl 4.7.3: the sheet at least 20 mm wider than the leaf it sits in |
| Catch it | As the DPC is laid, before the next course covers it. Photograph both faces with the projection in shot, and look again before render or paving. |
2. Weepholes are missing or too far apart
There are no weepholes above a flashing, or too few, so water that collects on the flashing inside the cavity has no way out.
| NCC 2025 | F1P1; B1D4 and F1D15(1)(a): masonry to AS 3700 |
| NCC 2022 | F3P1; B1D4 and F3D5(1)(a) |
| Standard | AS 3700 cl 4.7.2: weepholes in the first course over every flashing, no more than 1200 mm apart; cl 12.4.14: made with a pipe, or by leaving some or all of the mortar out of a vertical joint |
| Catch it | As the course above each flashing is laid. Count them against the length of the run, with the calculator below. |
3. A window or door has no flashing, or the wrong one
Head, sill or jamb flashings are left out or do not follow the approved detail, so water gets past the frame into the cavity, the inner leaf or the room.
| NCC 2025 | F1P1(3) and (4): rain, including wind-driven rain, that the building collects is disposed of without unsafe conditions or undue damage; its note names external walls and the openings around windows and external doors; F1D14(1): windows and framed glazed doors to AS 2047 for resistance to water penetration |
| NCC 2022 | F3P1: the external wall, including the openings around windows and doors, must prevent water getting in that could cause dampness, deterioration or unhealthy conditions; F3D4(1) |
| Standard | AS 2047:2014 cl 7.2.2: flashing wherever water could otherwise get inside, cross the cavity to the inner leaf, or stay in the cladding instead of draining to its outer face; flashings to AS/NZS 2904, and in masonry to AS 4773.2. The approved detail sets where each flashing goes and its shape. |
| Catch it | Before each window goes in, against the approved detail, and again before render, cladding or linings cover it. Photograph the head and sill flashings. |
4. Weepholes sit below the level outside
The paving, balcony topping or garden outside is finished above the weepholes, so the cavity cannot drain, or drains into the paving bed.
| NCC 2025 | F1P1; B1D4 and F1D15(1)(a) |
| NCC 2022 | F3P1; B1D4 and F3D5(1)(a) |
| Standard | AS 3700 cl 12.4.14: nothing, mortar included, may block a weephole. The Library treats a finished floor or paving over a weephole as exactly that kind of blockage. |
| Catch it | At design: set the base flashing and its weephole course above the finished level outside. Check the levels again before paving and landscaping. |
5. The facade is combustible
A cladding panel, insulation or framing in the external wall is combustible in a building that needs a non-combustible one. Table C2D2 requires Type A construction for a Class 2 building with a rise in storeys of three or more, and Type B for a rise of two, unless C2D6 allows Type C (each sole-occupancy unit with access to two exits, or its own direct access to a road or open space). So the rule reaches most apartment buildings.
| Both editions | C1P2; C2D10(1)(a): in Type A or B construction, the external wall and everything in it, the facade covering, framing and insulation included, non-combustible. C2D10(5) and (6) list materials that may be used, and C2D10(4) exempts some components, among them damp-proof courses, and wall ties and other masonry components complying with AS 2699 Parts 1 and 3. |
| Standard | AS 1530.1, the combustibility test behind the definition of non-combustible: the 1994 edition under NCC 2022, the 2024 edition under NCC 2025 |
| In NSW | Since 15 August 2018, a ban under the Building Products (Safety) Act 2017 has also stopped aluminium composite panels with a core of more than 30% polyethylene by mass being used in the external walls, cladding, insulation, facades or rendered finishes of Class 2, 3 and 9 buildings of Type A construction with a rise in storeys of three or more, or Type B with two or more, unless the panel passes an AS 1530.1-1994 combustibility test, or the panel and wall assembly achieve both the EW and BB classifications under AS 5113 and the proponent declares by statutory declaration that it will be installed as tested. The test reports must be dated from 1 July 2017 and come from an Accredited Testing Laboratory. The ban names the 1994 test, whichever NCC edition applies. |
| Catch it | At product selection, before anything is ordered: for each layer, its place in the C2D10(5) or (6) lists or an AS 1530.1 test report. On delivery, check that what arrived matches the evidence. |
6. A flashing does not project far enough
Flashings and overflashings are built in but stop short of the face or turn the wrong way, so water running down the cavity or the wall is led back into the masonry instead of out of it.
| NCC 2025 | F1P1; B1D4 and F1D15(1)(a) |
| NCC 2022 | F3P1; B1D4 and F3D5(1)(a) |
| Standard | AS 3700 cl 12.4.16: flashings and overflashings built in with projections big enough, and turned the right way, to lead moisture out of the masonry; overflashings set at least 15 mm into the masonry (cl 12.4.16; designed for it under cl 4.7.3) |
| Catch it | As each flashing is laid, before the course over it, check that it reaches past the face and turns down. Check each overflashing's depth before it is sealed. |
How many weepholes does a run of flashing need?
Enter the length of one straight run of flashing, over an opening or along the base of a wall. The calculator lays the weepholes out evenly, no more than 1200 mm apart, the AS 3700 limit both editions call up.
When should each defect be caught?
Like the rest of the Library, these defects can be seen without testing, and each one is exposed for a short time before the next trade covers it:
| Stage | Check | Defects |
|---|---|---|
| Design and shop drawings | Window flashing details; the base flashing and its weepholes above the finished level outside; evidence that every facade layer is non-combustible | 3, 4, 5 |
| As each flashing course is laid | DPC past both faces; flashings past the face and turned down; overflashings 15 mm into the masonry; weepholes in the course above, 1200 mm apart at most | 1, 2, 6 |
| Window installation | Head, sill and jamb flashings to the approved detail, before render or linings | 3 |
| Facade delivery | The cladding and insulation delivered match the evidence | 5 |
| Before render, paving and landscaping | No render across the DPC; finished levels below the weepholes; weepholes clear | 1, 2, 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 construction: upload the wall sections and window details to a project and ask it to review them. It marks each issue it finds on the sheet, with the clause.
For the facade: name the cladding or wall system and it reads the product's CodeMark certificate from the register, where there is one, so you can see what the certificate covers before anything is ordered.
On site: it builds an inspection and test plan from your specification, with hold points like the ones above, and turns site photos and notes into a defect register and a draft direction notice, 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, Parts B1, C2 and F1, and NCC 2022 Volume One with Amendment 2, Parts B1, C2, F1 and F3, from the ABCB
AS 3700:2018, AS 2047:2014 and AS 1530.1 (1994 and 2024 editions), from Standards Australia
Aluminium composite panel ban, NSW Government
This is part 4 of five in our rewrite of the Building Defects Library. The others cover waterproofing, fire safety, structure and services, and the series index lists all 40 defects.
Questions this guide answers
Which building enclosure defects does the NSW regulator keep finding?
Building Commission NSW's Building Defects Library lists six that its auditors find often on apartment sites: a damp-proof course that does not project from the face of the brickwork, weepholes missing or too far apart, a window or door installed without adequate flashings, weepholes below the level outside, combustible cladding, and flashings that do not project far enough to shed water clear of the masonry. Building enclosure defects were reported in 23% of the 520 buildings in the 2025 strata survey.
How far apart can weepholes be?
AS 3700:2018 clause 4.7.2 puts them in the first course over each flashing, no more than 1200 mm apart. Under clause 12.4.14 nothing, mortar included, may block them, which the Library reads as keeping them above the finished level outside. NCC 2022 and NCC 2025 both call up AS 3700:2018, through B1D4 and the wall cladding clause (F3D5 in NCC 2022, F1D15 in NCC 2025).
Does a damp-proof course have to stick out of the brickwork?
While the wall is being built, yes. Under AS 3700:2018 clause 12.4.16 a sheet damp-proof course is laid to stick out past both faces as the wall goes up, then trimmed flush or folded down once the wall is finished, and render must never cover it. The material must comply with AS/NZS 2904 or be impervious sheet to AS 3660.1 (F1D6(2) in NCC 2022, F1D8(2) in NCC 2025); South Australia has its own version of that clause.
What changed for external walls in NCC 2025?
Part F3, roof and wall cladding, was folded into Part F1, whose rainwater Performance Requirement, F1P1, now also covers external walls and the openings around windows and doors. Rising damp has no national Performance Requirement in NCC 2025, only the Functional Statement F1F2, with damp-proofing among the Deemed-to-Satisfy clauses; South Australia inserts its own, F1P2. The clauses moved: glazed assemblies from F3D4 to F1D14, wall cladding from F3D5 to F1D15, damp-proofing from F1D6 to F1D8. For an apartment building they read the same. The fire rule for external walls, C2D10, did not change, but NCC 2025 calls up the 2024 edition of the combustibility test, AS 1530.1, in place of the 1994 edition; reports on the 1994 edition issued before the change remain valid.
Which NCC edition applies to a project in NSW?
NCC 2022 until NCC 2025 takes effect in NSW on 1 May 2027. The edition is decided by the date the construction certificate application is made, not when work starts, and the certifier confirms it for each project.
