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Facade Performance Solution: cladding, weatherproofing and the NCC

A facade Performance Solution shows that an external wall system which is not Deemed-to-Satisfy still meets NCC Performance Requirement F3P1, weatherproofing. We write them for builders, developers, architects and certifiers in NSW, Victoria and Queensland. A report typically runs $2,500 to $4,500 ex GST and issues in 5 to 10 working days.

What it is, and when the certifier asks for one

The NCC gives two ways to comply. Deemed-to-Satisfy is the lookup route: build to the referenced standards and the clause is met. A Performance Solution is the demonstration route: compliance with the Performance Requirement is shown rather than looked up. Both are full compliance.

For an external wall the Performance Requirement is F3P1: the roof and external walls, including openings around windows and doors, must prevent water penetration that could cause unhealthy or dangerous conditions, loss of amenity, or undue dampness and deterioration of building elements. Under A2G2 the solution relies on one or more of four assessment methods: evidence of suitability, a verification method, expert judgement, or comparison with the DtS provisions.

It usually arrives as a certifier's RFI at construction certificate stage, when the wall types schedule names a system with no DtS pathway. Nothing is wrong with the design; it has to be documented.

Systems that trigger one, and systems that do not

Plan on a Performance Solution if the external wall system is one of these:

• Rendered fibre cement systems, including render on blueboard
• Mineral wool and EPS external thermal insulation composite systems (ETICS)
• AAC panel systems with an applied render or coating
• Rainscreen and drained-and-vented cladding on battens or rails
• Most proprietary facades: composite panel, fibre cement panel with express joints, terracotta and metal cassettes

Each is Performance Solution territory, either on a current CodeMark certificate or by expert judgement. Brick veneer and cavity masonry are the main exceptions: masonry to AS 3700, or AS 4773.1 and AS 4773.2, is Deemed-to-Satisfy under F3D5 and needs no solution. Not sure where your wall sits? The External Wall System Finder and the NCC Performance Solution checker will tell you.

Two routes: CodeMark evidence of suitability or expert judgement with F3V1a

Every facade Performance Solution takes one of two routes.

1. A current CodeMark certificate. The certificate is evidence of suitability under Part A5 of the NCC: the system meets F3P1 inside stated conditions, typically a maximum design wind pressure, a storey limit, a substrate, a fixing pattern and a cavity requirement. The solution checks the project against every condition; where it sits inside them all, the certificate carries the weight.
2. Expert judgement supported by F3V1a. No certificate, a lapsed one, or a project outside its scope on any condition, and we assess the system ourselves: the Table F3V1a risk score and its installation rules, the site wind pressures, the manufacturer's test evidence and the junction details, with the judgement signed by us.

Some jobs mix both: the certificate covers the wall, expert judgement the one junction it does not.

What the report contains

A missing part is the usual reason for a rejection.

• The Performance Requirement, answered limb by limb. F3P1(a) and F3P1(b) each addressed for the specific building, not a general assurance that the product is good.
• The assessment method, named under A2G2, with the reason it applies.
• Site wind pressures with local pressure factors. Ultimate design pressures from AS/NZS 1170.2 for the field, edge and corner zones of the wall; the same numbers go on the drawings. Houses take a wind class from the AS 4055 wind classification calculator.
• The F3V1a score with its breakdown. All six factors, the selection for each and the total, so the certifier can check it.
• The system and the certificate, with its revision and expiry as at the date of the report.
• Conditions and inspection hold points. What must be built, inspected and photographed before the next trade covers it: barrier laps, cavity battens and drainage openings, window flashings, balcony and parapet junctions. Certifiers read this part first.

Five things that get a facade Performance Solution rejected

1. Answering the wrong question. A report that recites the CodeMark certificate and never addresses F3P1 is a product summary, not a Performance Solution.
2. Wind pressures that do not match. The wind report, the solution and the drawing notes must carry the same number. This is the most common rejection we see.
3. Local pressure factors left out. A field pressure used at the corners and edges understates the suction the cladding and its fixings must resist.
4. A risk score with no breakdown. A total without the six factor selections cannot be checked, and an unauditable number is worth nothing to a certifier.
5. An expired or superseded certificate. Certificates lapse and get revised; we check the register when we write.

Worked example: rendered fibre cement, four-storey Class 2

A certifier issued an RFI on a four-storey residential building in suburban Sydney: steel-framed walls with a rendered fibre cement system, a flat roof behind parapets, eaves under 600 mm, exposed balconies on the upper levels and a second feature cladding at the entry. The system held a current CodeMark certificate, so the solution took route 1.

The wind assessment put the site in Region A2, terrain category 3, top of wall about 13 m. In round numbers: about 0.9 kPa positive and 0.8 kPa suction in the field of the wall, and about 1.4 kPa suction at the corners once the local pressure factor was applied. The corner figure went on the drawings and was checked against the certificate's limit.

The F3V1a score: wind region A2, 0; more than two storeys, 4; roof-to-wall junction fully exposed behind parapets, 3; eaves under 600 mm above two storeys, 5; complex form with two cladding types, 1; exposed balconies at the second floor or above, 6. Total 19, the High band: no specific design, but the rendered system could not be direct fixed and had to go on a drained and vented cavity.

So the solution stated that the project sat inside the certificate on pressure, height, substrate and risk band; specified the cavity, barrier and drainage openings; set the corner suction as the fixing design pressure; answered F3P1(a) and (b); and listed the hold points. A third cladding type at the entry would have lifted the total to 21 and triggered a specific weatherproofing design: see what a score over 20 means and five design moves that lower the score.

NSW: the Design and Building Practitioners Act

In NSW the facade design for a Class 2 building, or a building with a Class 2 part, is a regulated design under the Design and Building Practitioners Act 2020. The Performance Solution behind it is declared by a registered design practitioner in the relevant class and lodged on the NSW Planning Portal before that work starts. We hold DEP0001529 in the Facade class, so the wind assessment, the solution and the declaration come from one practitioner and the numbers match. In Victoria and Queensland there is no equivalent declaration; the solution goes to the building surveyor or certifier with the permit documentation. More on our facade engineering page.

Fees and turnaround

Bands are indicative and ex GST; every project is quoted on its own brief. The NCC Performance Solution hub has the full fee table; the waterproofing Performance Solution page covers a window in a shower or any other wet-area departure.

Common questions