Frequently Asked Questions

What is MAXRaft?

A thermally broken slab that is also fully insulated; the only one of its kind on the market. A MAXRaft slab achieves r-values 3x the NZ building code and will improve the performance of your home from the foundation up.  

Who provides the Engineering design?

As a part of our package, MAXRaft has it's own fully qualified engineers who can provide a site specific engineering design. Alternatively if you would like to use your own engineer then we can work in with you to ensure a smooth design process. 

Why should I choose MAXRaft?

You can change your windows, you can replace your carpet, you can buy a new kitchen...

You can't change your foundation.

MAXRaft® is a great choice for any home.  MAXRaft® acts as the thermostat for your home which means the temperature does't' fluctuate as much as other floors. This constant temperature reduces the susceptibility of your home to mould growth and assists in providing a warm and healthy living environment.

What kind of technical support does MAXRaft provide?

We supply a full onsite guide to builders and owners, architects and engineers, which supports the site specific PS1.  There is also a technician who can be reached by dialing 0800 MAXRAFT. or ask a question via our website.

Can I use MAXRaft with 90mm frames?

Yes. MAXRaft is suitable with 90mm frames or wider frames.  When used with 90mm frames MAXRaft will recommend specific bolt fixings to ensure requirements are met. This is not necessary if the frames are 140mm +.

How is MAXRaft installed?

MAXRaft® is available in two ways; either as supply of the MAXRaft insulation only OR as a fully installed slab system by MAXRaft's installers. MAXRaft® has a comprehensive Onsite Guide and with guidance from the MAXRaft® team any full trained builder can install a MAXRaft system.   

How do I coat the outside of MAXRaft?

There are a few different options for coating the outside edge of MAXRaft® from a Hard Edge to a Plaster finish. Please see our Protecting MAXRaft® page.

What sets MAXRaft apart from similar methods?

Warmer, healthier and more energy efficient homes.

Increased thermal efficiency & higher R-values., Less time on site, Site specific engineering, Reliable proven construction details.

What is the width of the MAXRaft perimeter insulation?

The standard MAXRaft detail shows a taper that goes from 50mm to 20mm at the top.  This detail is used when MAXRaft is constructed with 90mm frame.  For frames that are 140mm+ we can remove the taper altogether to give you additional insulation.

Can MAXRaft be installed anywhere?

Yes.  MAXRaft® is available nationwide and can be custom engineered to work on  almost any site,.  MAXRaft has systems that are suitable for good and soft ground including TC2 and piled sites.  MAXRaft is not generally suitable for TC3 land unless the ground can be remediated to TC2.

How do I go about ordering a MAXRaft floor?

Simply email a full set of your plans along with a Geotech report (if applicable) to  We can produce a quote for you within 1 business day.  Following acceptance of the quote and consent being issues we generally require 3 weeks notice to be onsite.

How environmentally friendly is MAXRaft?

Known for its highly efficient insulating properties, Expanded Polystyrene (EPS) has long been a leading choice in the industry for energy efficient homes. Plastics New Zealand has designated EPS as compatible with the environment as a result of its insulation ability. The waste produced in the MAXRaft® production process is recycled and eventually turned into new EPS insulation.

How long does it take to install a MAXRaft slab?

For a standard 200m² house on good ground we would allow approximate 5 days to start and pour the slab. 

If we already have consent for a standard slab can we change to a MAXRaft floor?

Yes, we will supply an engineered foundation package and you will simply have to fill out a variation to your building consent.

How does MAXRaft perform in an earthquake?

All MAXRaft slabs require site specific engineering design and are generally designed to be floating to minimise the risk of seismic damage.

Can MAXRaft be used in conjunction with underfloor heating?

Yes, they are a perfect match. Because the MAXRaft® is fully insulated underfloor heating works extremely well as it will prevent heat loss around the perimeter of the slab.  We have seen efficiencies of 30 – 40%. 

What is the R Value of a MAXRaft

Because all floors are different the R value varies but a typical MAXRaft® foundation has an R-value of approximately R4. Try our calculator here (opens in MS Excel).

How does MAXRaft perform with a polished concrete floor?

Excellently. Because the MAXRaft® isn’t tied to ground, the concrete will shrink when curing resulting in a stronger slab.  You can never guarantee a slab will not crack, however please ask us for tips on how you can minimise the risk.