An engineered foundation
NZS 3604, the standard most timber-framed houses are built to, covers timber and concrete piles but not screw piles. So screw pile foundations are a specific engineering design: an engineer designs them for the building and the site, and that's how they meet the Building Code, under clauses B1 (Structure) and B2 (Durability).
Producer statements
For consented work, councils rely on producer statements:
- PS1, design: the engineer's statement that the design meets the Building Code. It goes in with the consent application.
- PS2, design review: another engineer's check of the design, when council asks for one.
- PS3, construction: our statement that the piles were installed to the design, with the torque records.
- PS4, construction review: the engineer's statement that they've reviewed the installation.
Consent, or exempt?
Whether you need a building consent depends on what you're building, not on the foundation. Many small decks, sheds, sleepouts, carports and pergolas are exempt under Schedule 1 of the Building Act if they meet its conditions, and from 2026 so are small standalone homes up to 70m². Houses, extensions and most relocated homes need consent.
Exempt work still has to meet the Building Code, so the piles still need to suit the structure. Your designer or council has the final say on whether you need consent.
Inspections
Council may want to inspect the piles before the floor goes on. Because screw piles are ready as soon as they're in, that inspection can happen as soon as we finish.
Working with your engineer
Already have an engineer? We'll install to their design and give them what they need for sign-off. If you don't, we can organise the engineering for you.