Bracing resilience check

Prototype: illustrative figures

Building codes are designed to save lives.
What would it take to save your home too?

Choose a different path
Site subsoil class (if known)

Defaults to site class C.

Knowledge of seismic hazard across Aotearoa has changed since the current house design rules (NZS 3604) were written. In your area, the latest models suggest a hazard that is no higher than what NZS 3604 already requires to achieve minimum performance.

Meeting only that minimum can still leave a home needing extensive repairs - independent research suggests around 50% more bracing is needed to limit damage.

Want the technical basis?

This combines two independent sources: the 2022 National Seismic Hazard Model (as documented in TS 1170.5:2025), which is behind the hazard increase above, and BRANZ Study Report SR337 (2015), which found that homes built only to the NZS 3604 minimum may need around 50% more seismic bracing to limit damage in a design-level earthquake, rather than just meet the life-safety standard.

The updated hazard model itself points to no increase here - any extra bracing shown above comes entirely from the SR337 damage-control margin, not a change in seismic hazard. Consider speaking with your designer about what a low damage outcome might look like for your project. They can input the design numbers into the designer tab of this tool for a more detailed consideration.

Talk to our engineers

This is a provisional, area-level indication. Once you have a concept design with bracing numbers, the designer view (or our engineers) can show the specific picture for your home.

Reduce the demand instead

Adding bracing capacity is not the only option.

FrontFoot® takes the other pathway: it reduces the level of shaking that reaches your home's structure in the first place, rather than adding capacity to resist it.

Learn about FrontFoot

How does your town or city stack up against others?

Here is a selection of towns and cities across New Zealand, and their relative seismic risk for a NZS 3604 structure - largest first. Dark blue is NZS 3604’s own demand for that town’s earthquake zone; mid blue, where present, is how much higher the latest hazard modelling (TS 1170.5:2025) pushes that for this specific town; light blue is the added SR337 margin on top, considering what might be required to reach a low damage outcome rather than just the life-safety minimum. Figures are unitless - useful only for comparing towns relative to each other, not as bracing units.

Site subsoil class

Defaults to site class C.

Hover over any bar to see which town or city it is

CartertonMastertonFeatherstonGreytownUpper HuttLower HuttWellingtonPoriruaPahiatuaDannevirkeParaparaumuWaikanaeLevinOtakiWaipukurauAshhurstWaipawaPalmerston NorthBlenheimFoxtonHavelock NorthKaikouraCliveGisborneHastingsRenwickFeildingGreymouthHokitikaLake HayesNapierPictonQueenstownTe AnauWairoaMartonAlexandraArrowtownBrightwaterChristchurchCromwellDarfieldKaiapoiKawerauLeestonLincolnLytteltonMotuekaNelsonNgongotahaOhopeOpotikiOxfordPegasusPrebbletonPutaruruRangioraRichmondRollestonRotoruaTaumarunuiTaupoTe PukeTokoroaTurangiWakefieldWanakaWest MeltonWestportWhakataneWhanganuiWoodendAshburtonAucklandBalcluthaBeachlandsCambridgeDargavilleDunedinGeraldineGoreHamiltonHaweraHelensvilleHibiscus CoastHuntlyInglewoodInvercargillKaikoheKaitaiaKatikatiKerikeriKihikihiKumeu-HuapaiMaraetaiMatamataMiltonMorrinsvilleMosgielNew PlymouthNgaruawahiaOamaruOmokoroaOne Tree PointOtorohangaPaeroaPokenoPukekoheRaglanRiverheadRuakakaSnells BeachStratfordTaurangaTe ArohaTe AwamutuTe KuitiTemukaThamesTimaruTuakauWaiheke WestWaihiWaihi BeachWaimateWaitaraWaiukuWarkworthWellsfordWhangamataWhangareiWhitiangaWintonChristchurch
NZS 3604 demandTS 1170.5:2025 excessSR337 low damage marginChristchurch (selected above)

Town / city

Disclaimer

This tool indicates relative demand, not a design specification. Any build requires specific engineering consideration. Preliminary information only, not professional engineering, legal, or insurance advice. Figures shown throughout this page are illustrative placeholders, not final figures. The moderate, high and extreme shift bands are illustrative cutoffs, not final thresholds. Worked-example bracing units for the curated locations, and baseline estimates for every other location, are placeholders too, not location-specific NZS 3604 calculations. The SR337 uplift factor is set from the recommendations in BRANZ SR337 for what it might take to achieve a low damage outcome.