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TTT Raft Foundations

Our Raft Foundations are designed to support your building during major lateral movement and loss of ground support. They deliver the same performance as structures recommended in MBIE Guidance 2012, but are an economical alternative.
How it’s done

TTT Raft Foundations use TTT MultiPole UniLogs to form a lattice of strong, lightweight foundation beams. This ‘raft’ is designed to have a four metre internal span and a two metre cantilever at the edge, should your building lose ground support.

We’ll install your raft using a small, 5 tonne digger. There’ll be minimal ground loading and excavation required, with any materials we do excavate being placed back in-between beams and compacted.

If you’re planning on having a concrete slab, we’ll place a working platform of hardfill between the beams. For a timber floor, we’ll fix pre-scalloped UniLog jack studs at the intersections of beams to support timber bearers.

Benefits of this system

•  Typical construction time of 5 days.

•  Lightweight – suitable for ground with ultimate bearing capacity of 100kPa or less with specific design.

•  Able to be designed for more than 300mm of lateral movement.

•  Timber floors are able to be re-levelled following seismic events.

•  Uses award-winning TTT MultiPoles.

•  PS1, PS3 and PS4 provided.

Additional design options

If your ground is in exceptionally poor condition, we can install TTT Ground Improvement underneath your TTT Raft Foundations.

If you’d like specialised bearers and joists we can design these for you, either in accordance with NZS 3604 or according to specific design.

This system can accommodate timber floors with attached garages.

Quick reference information
Technical category Type of MultiPole used Typical pole diameter Typical pole length Typical pole spacing Typical installation method
Residential foundations TC2 & TC3 UniLog 250–300mm To suit house dimensions 2.0–2.4m 5 tonne excavator
  • Compare quick reference information

    Foundation system Technical Category Type(s) of MultiPole used Typical pole diameter Typical pole length Typical pole spacing Typical installation method
    TTT Deep Pile Foundations Residential foundations TC2 & TC3 SED 150–250mm 1.0–22.0m
    Poles can be joined
    to reach greater depths
    3.0–4.0m High frequency vibration
    Commercial foundations TC2 & TC3 SED 250–300mm 1.0–22.0m
    Poles can be joined
    to reach greater depths
    3.0–4.0m High frequency vibration
    TTT Ground Improvement Residential foundations TC2 & TC3 Uglie 200–300mm 2.4–4.8m 1.0–1.5m High frequency vibration
    Commercial foundations TC2 & TC3 Uglie 300mm 6.0–15.0m 1.0–2.5m High frequency vibration
    TTT Suspended Floor Foundations Residential foundations
    (as per TTT Deep Pile Foundations)
    TC2 & TC3 SED 150–250mm 1.0–22.0m
    Poles can be joined
    to reach greater depths
    4.0m High frequency vibration
    Bearers TC2 & TC3 UniLog 350mm To suit house dimensions 4.0m Fastened to
    scalloped pile tops
    TTT Raft Foundations Residential foundations TC2 & TC3 UniLog 250–300mm To suit house dimensions 2.0–2.4m 5 tonne excavator
    TTT Under House Piling Residential foundations TC2 & TC3 UniLog 180–200mm 1.0–2.4m
    Poles can be joined
    to achieve depths of 8.0m+
    1.0–4.0m High frequency vibration
    using compact piling
    equipment
    TTT Bridges Foundations TC2 & TC3 SED 150–300mm 1.0–22.0m To suit bridge dimensions High frequency vibration
    Bearers TC2 & TC3 UniLog 250–450mm 1.0–12.0m To suit bridge dimensions Fastened to scalloped
    pile tops

Find out more about the Raft Foundation system

It’s just a few, easy steps toward a strong foundation

1

2

3

Geotechnical report

Site-specific design

Site visit and installation

First of all, we’ll need a geotechnical report for your site. If you don’t have one of these, we’ll help you get one.

This will be based on your geotechnical report, and could involve the customisation of one or more of our existing foundation systems.

Our installation processes are fast and efficient. They’ll have minimal impact on neighbouring properties and will leave your site undamaged.

4

Sign off

Issuance of PS3 and PS4 documentation.

You now have excellent foundations to build on!

START THE PROCESS TODAY

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