Does double glazing need a building consent in New Zealand?
Usually not. Schedule 1 Exemption 8 covers window work in an existing dwelling of up to two storeys, with conditions. Here are the conditions, in homeowner terms.
By the NZ Double Glazing team
Key takeaways
- Exemption 8 of Schedule 1 of the Building Act covers window and doorway work in an existing dwelling, and MBIE's guidance frames it around buildings of up to two storeys.
- The exemption depends on the window being replaced not having failed its 15-year durability requirement.
- Exempt means exempt from the consent process, not from the Building Code. The work still has to comply.
- If the new units are heavy enough to need the frame or lintel strengthened, that structural work can take the job outside the exemption.
- Ask your glazier to confirm exemption in writing at the measure, before you sign anything.
Usually no. Schedule 1 Exemption 8 of the Building Act exempts window and doorway work in an existing dwelling from needing a building consent, on conditions — MBIE's guidance covers buildings of up to two storeys and requires that the window being replaced has not failed its 15-year durability requirement. The work must still comply with the Building Code.
What Exemption 8 covers
Schedule 1 lists building work that can be done without a consent. Exemption 8 is the windows and doorways one: replacing a window or a doorway in an existing building, within the existing opening. Retrofit double glazing sits comfortably inside it, and so does a straight like-for-like window replacement, provided the conditions are met.
The conditions, in plain terms
- It is an existing dwelling, and MBIE's guidance is written around buildings of up to two storeys.
- The window being replaced has not failed its 15-year durability requirement. A window that has failed early is a signal something else is wrong, and the exemption does not cover papering over it.
- The work stays within the existing opening. Making the opening bigger or putting a door where a window was is a different job.
- No structural change. If heavier units mean the lintel or the framing needs work, that structural work is not what Exemption 8 covers.
Exempt is not the same as unregulated
This is the part homeowners are most often surprised by. Exempt building work still has to comply with the Building Code: weathertightness, structure, durability, the lot. There is simply no council checkpoint. If the work is done badly, the fact that it did not need a consent is no defence, and it can surface at sale time.
When you probably do need a consent
- You are enlarging, moving or creating an opening.
- The window is part of a structural element, or the new units need the lintel or framing strengthened.
- The existing window has failed its durability requirement, which points at a wider problem.
- The building is not a straightforward existing dwelling — three or more storeys, or a different use class.
- There is a heritage or resource-management overlay. That is a district-plan question, separate from building consent, and your council answers it.
How we handle it
The measure is where this gets settled. The glazier looks at the frames, the lintels and the unit weight, and we say in writing whether we consider your job exempt, or whether it needs a consent before anything is ordered. If it needs one, you find out before you have paid a deposit, not after.
Questions
Do I need consent to retrofit double glazing?
In most existing homes, no. Schedule 1 Exemption 8 covers window work in an existing dwelling on conditions, including that the window being replaced has not failed its 15-year durability requirement. Your council is the final word on your specific job.
What does 'up to two storeys' mean for my house?
MBIE's guidance for this exemption is framed around buildings of up to two storeys. If your house is taller, or the work is on a taller part of it, ask your council before you book anything.
Does exempt work still have to meet the Building Code?
Yes. The exemption is from needing a consent, not from the Code. The work has to comply either way; there is just no council inspection of it.
What if the frame needs strengthening?
Sealed units are heavier than single panes. If that means structural work to a lintel or framing, that part is not covered by Exemption 8 and a consent may be needed. The glazier flags it at the measure.
Is a heritage listing the same thing as building consent?
No. Heritage and character controls come from your district plan and are handled through resource consent, separately from building consent. Check both with your council if your house is in a controlled area.
Who is responsible if exempt work is done badly?
The person who did it, and in practice you, when it turns up at sale. That is the argument for a written contract and a documented specification even on work that needs no consent.
Sources
Published 15 September 2026, last updated 15 September 2026 by the NZ Double Glazing team.