Window replacement and building consent: what NZ joiners need to know

Most window and door jobs are a straight swap, and most straight swaps need no consent. The trouble starts at the edges: a bigger opening, a leaking unit, a stair or balustrade that sits inside a consented job. This guide sets out where the consent line falls for joinery, when installing windows and doors becomes restricted building work that needs a Licensed Building Practitioner, and which records (Record of Work, H1 window performance, F4 barrier heights) you should hand over at the end.

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When a like-for-like swap needs no consent

Schedule 1 of the Building Act 2004 lists building work that does not need a building consent. Exemption 1 covers general repair, maintenance and replacement: replacing a component or assembly with a comparable one in the same position is exempt. For windows and exterior doors in existing dwellings and outbuildings there is also a more specific exemption (Schedule 1 exemption 8, covering windows and exterior doorways). In both cases the exemption is conditional. The replacement must be comparable in the same opening, it must not modify a specified system such as a sprinkler or fire alarm, and the unit being replaced must not have failed the Building Code durability provisions. Exempt work still has to comply with the Building Code, so the new unit cannot make the house worse in weathertightness, glazing safety or thermal performance than what was there. MBIE publishes technical requirements for each exemption on building.govt.nz, and they are worth reading before you tell a customer that no consent is needed.

The catch: a window that failed early

The clause that trips joiners up is durability. If the window or door you are replacing has failed to meet the durability requirements of the Building Code, for instance because it has leaked through a flashing or sill defect well before it should have, the exemption does not apply, even if the new unit is identical and goes in the same hole. In that case the replacement needs a building consent. In practice, a leak is a diagnostic problem before it is a joinery problem: the fault may be the flashing, the sill detail or the cladding junction rather than the unit, and fixing that is building work that must comply with Building Code clause E2 External Moisture. Before you quote a replacement for a leaking window, find out how old it is, what failed, and whether the council needs to be involved. Put the answer in writing on the quote. If the situation is borderline, the building consent authority at your local council can tell you, and a short email chain is cheap insurance.

New and altered openings, and consented jobs

Cutting a new opening, enlarging an existing one, or changing a window to a different type or position is not a comparable replacement in the same position, so it falls outside the exemption and needs a building consent before work starts. A structural wall opening also brings in the structural clauses, which means someone has to design the lintel or beam. If your joinery is part of a larger consented build or renovation, the work is consented work whatever it looks like in isolation, and your installation will be inspected as part of the consent. The questions to ask before you price any job are: is the opening staying the same size and position, is the unit being replaced of comparable type, did the old unit fail early, and is this job already under a consent. Our building consent tracker page covers keeping track of consent status once you have a number.

Restricted building work: installing exterior windows and doors

Restricted building work (RBW) on a house is work that needs a building consent and relates to the primary structure or the external moisture-management system, and windows and doors are part of that moisture-management system. So installing exterior windows and doors under a building consent is RBW. It must be carried out or supervised by a Licensed Building Practitioner, and for joinery installation that means the Carpentry licence class (or a Site licence supervising). There is no separate “Joinery” licence class. When the RBW is finished, each LBP who carried out or supervised it must give a Record of Work to the owner and to the council under section 88 of the Building Act. No consent means no RBW, so a like-for-like exempt replacement does not generate a Record of Work, and RBW applies to residential buildings rather than commercial ones. If you employ unlicensed installers, make sure an LBP is genuinely supervising. Our LBP Record of Work page has the plain-English summary.

H1 window performance and F4 stairs and barriers

On consented work, new glazed openings must meet Building Code clause H1 Energy Efficiency. Window performance is the construction R-value of the whole window, frame and glazing together, and it is shown on each window’s WEERS certificate or in the designer’s H1 calculation, so the glazing type alone proves nothing. H1/AS1 6th edition has applied since 27 November 2025, and the 5th edition may still be used for consent applications lodged before 27 November 2026. Ask the designer or builder which method the consent uses, and file the WEERS reference with the job. For stairs, landings and balustrades, clause F4 Safety from Falling applies, with the barrier height and opening limits set in F4/AS1 for the building use and location. There is no single height that fits every job, so read it off the acceptable solution or the consented drawings, build to it, then measure and record the as-built height and opening sizes. A stair or balustrade that goes in as part of a consented build is inspected as part of that consent.

Putting the right records on the job

A joiner who finishes a consented window job should leave behind four things: the consent number, the Record of Work signed by the LBP, the WEERS certificate or H1 calculation reference for each window with its construction R-value, and, where stairs or barriers are involved, the F4 measurements. Toolie’s joiner pack works out which of those apply from a few facts about the job: external windows or doors, new opening or like-for-like, replacing existing windows, stairs or balustrade, and whether it is under a consent. It marks building consent as needed or not (with the reasoning shown, including the durability exclusion), lists the H1 window record and the Record of Work when the work is consented RBW, and lists an F4 record when stairs or barriers are involved. It is a checklist and a place to hold the records, not a substitute for the standards or the council’s view. For quoting see Toolie for joiners.

Sources

Official sources this guide relies on. Rules change, so check the current version before relying on a date or threshold.

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Common questions

Do I need building consent to replace a window in NZ?

Often not. Replacing a window with a comparable unit in the same position is generally exempt under Schedule 1 of the Building Act 2004, as long as the old unit has not failed the Building Code durability provisions and no specified system is affected. A new, larger or relocated opening needs consent.

What if the existing window has been leaking?

A window that failed the durability provisions, for example by leaking early, falls outside the exemption, so replacing it may need a building consent even if the new unit is identical. Find out why it leaked, since the cause may be flashings or cladding, and check with your council.

Is installing windows and doors restricted building work?

Yes when it is done under a building consent on a residential building, because windows and doors are part of the external moisture-management system. A Licensed Building Practitioner (Carpentry, or Site licence supervising) must carry out or supervise it and provide a Record of Work. Exempt like-for-like replacements are not restricted building work.

Is there an LBP licence class for joiners?

No. There is no Joinery licence class. For installing windows and doors as restricted building work, the relevant licence is Carpentry, or a Site licence where the LBP supervises.

What do I give the owner when a consented window job is finished?

The LBP’s Record of Work goes to the owner and the council. You should also pass on the H1 window performance details (WEERS certificate or calculation reference and each window’s construction R-value) and, for stairs or balustrades, the as-built F4 barrier heights and openings.

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