DatumDesk
By verdict

Four times the certifier asked for more than the code requires, with the clause

Sometimes the certifier is applying a rule of thumb rather than the rule. A barrier the whole way round a deck. Climbable rails at a three metre fall. A 2.4 m ceiling in an attic. A winder going measured at the string. Each is a reasonable instinct, and each asks for more than the provision does.

These are four real questions where the deemed-to-satisfy clause stops short of the request. The way to use them is not to win. It is to ask, with the page open, which clause requires the extra. Most certifiers will look, and most will agree.

Sarah-Jane Kavanagh, DatumDesk · Updated 13 October 2026

How to read each one. The question as it was asked, the verdict, and the citation in the form Document, Clause, Page. Every item links to the full published answer with all of its sources. Adoption differs by state, so confirm with your state building authority.
  1. 01

    Horizontal rails are only banned as climbable where the fall is more than 4 m.

    Climbable means something specific. The ban on horizontal elements between 150 and 760 mm applies where the fall is more than 4 m, measured to the surface beneath. At 3 m the deemed-to-satisfy rule does not bite. What does still apply is the 125 mm opening and the 40 mm edge gap, and a solid bottom panel is not a defined fix. Argue the right point.

    QLDClass 1NCC 2022
    The questionOur Toowoomba first-floor balcony has a horizontal-rail balustrade, and the certifier says the rails make it climbable. The drop is about 3 m. What does the code say about climbable elements, and does a solid panel at the bottom fix it?

    The answer. Not at 3 m, on the deemed-to-satisfy rules: the ban on climbable horizontal elements between 150 mm and 760 mm above the floor only applies where the fall is more than 4 m, measured to the surface beneath. The 125 mm opening and 40 mm edge gap rules still apply, and a solid bottom panel is not a defined fix in the Standard.

    ABCB Housing Provisions Standard (NCC 2022), 11.3.3(1) Barriers to prevent falls, p. 301

    Read the full answer with every source
  2. 02

    The 1 m barrier trigger is measured point by point along the deck edge, not for the deck as a whole.

    The one metre fall is tested at each point along the deck edge, not across the deck as a whole. A barrier is required along the far sections where the drop reaches a metre, and not at the 800 mm house end. The answer suggests asking the certifier to name the clause behind a whole-of-perimeter call, which is the politest sentence in this series.

    QLDClass 1aNCC 2022
    The questionOur deck on a sloping Brisbane block sits 800 mm above ground at the house and about 1.3 m at the far corner. The certifier wants a barrier the whole way round. Where exactly does the 1 m trigger bite?

    The answer. The 1 m fall test is measured at each point along the deck edge, not across the deck as a whole, so a barrier is required along the far sections and not at the 800 mm house end. Ask the certifier to name the clause behind a whole-of-perimeter call.

    ABCB Housing Provisions Standard (NCC 2022), 11.3.3(1) and Figure 11.3.3a, p. 301

    Read the full answer with every source
  3. 03

    Winders are allowed, and the going is measured in the middle, not at the inside edge.

    Winders are allowed, up to three in place of a quarter landing, and the going is measured at the middle of a stair up to a metre wide, or 400 mm in from each side on a wider one, where it must be at least 240 mm. The inside edge will always fail. The Standard does not measure there.

    SAClass 1NCC 2022
    The questionOur Adelaide Hills staircase turns with three winders, and the certifier says the going is too narrow on the inside. How are goings measured on winders, and is a winder even allowed in a Class 1 house?

    The answer. Winders are allowed: up to 3 in lieu of a quarter landing, so a three-winder turn is fine in principle. The going is not tested at the narrow inside edge but at the middle of the stair (up to 1 m wide) or 400 mm in from each side (over 1 m wide), and it must be at least 240 mm there.

    ABCB Housing Provisions Standard (NCC 2022), 11.2.2(3)(a) and (b), 11.2.2(4)(a)(i) and (ii), p. 291

    Read the full answer with every source
  4. 04

    Under a raked ceiling the height is tested over two thirds of the floor, an attic bedroom needs 2.2 m, and over a stair 2.0 m is enough.

    Under a raked ceiling the required height only has to be met over two thirds of the floor area, after anything under 1.5 m is excluded, and an attic habitable room needs 2.2 m rather than 2.4. Over a stair the minimum is 2.0 m, not 2.1. Three numbers the certifier rounded up, and three clauses that round them back down.

    NSWClass 1aNCC 2022
    The questionOur Sydney loft conversion has a raked ceiling, and the certifier says the new bedroom doesn't meet the 2.4 m ceiling height. How is height measured under a sloping ceiling, and what applies over the stair?

    The answer. Under a sloping ceiling the required height only has to be met over two-thirds of the floor area, after excluding anything lower than 1.5 m, and a habitable room in an attic needs 2.2 m rather than 2.4 m. Over a stair the minimum is 2.0 m, not 2.1 m.

    ABCB Housing Provisions Standard (NCC 2022), 10.3.1 and Figure 10.3.1, p. 263

    Read the full answer with every source
The pattern

What these have in common.

All four are barrier, stair and ceiling calls, which is not a coincidence. These are the provisions with the most dimensions in them, and dimensions get rounded up in memory. Nobody remembers 760 mm. Everybody remembers climbable.

A certifier who asked for the extra is usually not wrong about the risk. They are wrong about the clause. Give them the clause and let them decide whether to insist. That keeps the relationship, and the record shows you asked.

Where these came from

Every answer above was produced by DatumDesk.

DatumDesk answers Australian National Construction Code (NCC) compliance questions with clause citations, drawing on NCC 2022 and NCC 2025, state and territory variations, and ABCB handbooks. The commentary on this page is ours. The question, the verdict and the citation on each item are the published answer, verbatim, and the full answer with every source is one click away.

Browse all published answersCheck which edition applies in your state
Questions practitioners ask

Before you rely on any of this.

Should I push back on a certifier?

Ask which clause, with the page open. That is a question any certifier can answer and most will. If they insist beyond the deemed-to-satisfy provision, the record shows what was asked and why, which is what the DatumDesk project register is for.

Why are there only four?

Because the base rate runs the other way. The companion list has ten where the certifier was right. These four are published because they come up constantly and cost real money when they are conceded.

Which NCC edition applies in my state right now?

It depends on the state and, in some, on the lodgement date. Victoria and Western Australia are on NCC 2025, with Western Australia allowing an election for NCC 2022 until 30 April 2027. The ACT allows either edition until the same date. New South Wales, Queensland, South Australia (for building work) and Tasmania move on 1 May 2027. The Northern Territory has disapplied NCC 2025 until the next edition. DatumDesk keeps a per-state status page at datumdesk.ai/ncc-2025 and every answer leads with the edition operative in your jurisdiction. Adoption differs by state, so confirm with your state building authority.

How are DatumDesk answers checked?

Answers are generated only from an indexed corpus of the NCC volumes, the Housing Provisions, state and territory variations, ABCB handbooks and referenced regulation. Every numeric value is cited to a document, clause and page. Practice notes are labelled as interpretive. Licensed Australian Standards are named and deferred to, never reproduced. Where the corpus does not hold the answer, DatumDesk says so instead of guessing.

Does DatumDesk replace a building surveyor or certifier?

No. The certifier makes the call and carries the authority. DatumDesk makes sure you arrive at that conversation with the clause, the edition and the page already in hand, and that your question is on the record.

What does DatumDesk cost?

DatumDesk Pro is AU$19 a month or AU$190 a year, per practitioner, with every feature on both. The first 14 days are free. Cancel any time from your account.

Next

The next one is on its way.

When the next pushback is not on this page, ask DatumDesk. The answer comes back with the clause, the document and the page, for the edition your job is on, and it stays on your project record.

Ask DatumDesk your own question

Free for the first 14 days. AU$19 a month after that, cancel any time.