Designers and Specifiers | Maxraft

Why Specify MAXRaft®?

A solution for any scenario under the building code requirements makes MAXRaft products a great solution. 

Whether you are designing a home in Climate Zone 1 or 6, with or without underfloor heating and on good or soft ground we have a solution for you.  Check out our R-value Calculator.

As society changes, along with the economy and environment, changes are happening in the way homes are built. People are beginning to become more concerned with the environmental and health impact their home will have, and with the amount of energy it uses. Those involved in specifying higher quality, sustainable building materials that meet these needs are moving to the fore. A fully insulated MAXRaft® is a great way to start any design.

It is important to take the thermal efficiency of products into account when selecting the right product for your client. The thermal properties of a building, along with its thermal mass performance, ultimately impact on the energy used in heating and cooling a home. MAXRaft® products can offer R-Values between R1.5 to R5.25, allowing the homeowner to decide how much energy they use, rather than have it dictated by the weather.

MAXRaft® products are user-friendly for contractors, with a supply only option or fully installed by MAXRaft®. Any leftover polysytrene waste is recycled following the concrete pour.

MAXRaft is easy to specify and the engineering PS1 package can either be completed by MAXRaft, your own engineer or via the Specifi platform yourself.  You can view and download MAXRaft product details in PDF, DWG and Archicad in our Technical Section.

BRANZ Appraisal- At MAXRaft®, we want the consent process to be as easy as possible. To this end, we have been appraised for and received BRANZ Appraisal for the MAXRaft® stable of products. We combine this with our PS1 and foundation design service to make the consent process a breeze.



Why MAXRaft®

Performance Benefits

Today's homeowners want systems that have high thermal performance which provide increased energy efficiencies, prevent heat loss through the slab, neutralize thermal bridging and provide health and comfort benefits throughout their lifetimes. Check out the performance of our products here.

Energy Efficiency

MAXRaft® fully insulated foundations greatly reduce heat loss through the slab. With achievable R-values upto ~R5.25, this greatly increases energy efficiency, resulting in lower heating costs for the homeowner and greater comfort in the home environment. One of our clients has calculated the cost of underfloor heating for his home at 60.2c/m2 per month. 

MAXRaft® can help your clients reach the upper end of the Homestar rating (6 Homestar and above), and in the case of multi-dwelling projects in Auckland, ensure that your client will not fall foul of the 6 Homestar minimum for slab insulation.  Our products are often also used in Passive House.

If you want to see what the R-value could be on your client's home, please click here for our Product Selection Tool.

Iso-thermal analysis conducted by EZED Ltd in line with ISO 10211 comparing MAXRaft® to a traditional waffle slab show MAXRaft® is significantly warmer, providing comfortable warmth even in the middle of a South Island winter -0°C climates.


With site-specific design, MAXRaft® can be guaranteed to suit your client's structural requirements. All MAXRaft® fully insulated foundations are designed to ensure that the foundation matches the ground type on site, as well as taking into account all load bearing walls and point loads. Our engineers use standard details where possible in order to keep MAXRaft® as easy to use as possible.

Whether you are using a lightweight cladding, exterior bricks or stone cladding, we can come up with a solution for you.


MAXRaft® is currently constructed using different grades of New Zealand made CFC-free Expanded Polystyrene (EPS). An environmentally friendly product, EPS has long been used in the construction industry for providing lightweight, effective insulation.

Extruded Polystyrene (XPS) is also an option for perimeter footings and internal thickenings at an additional cost. With a compression strength of 300kPa and a slightly higher insulation value, XPS is an option when building a certified Passive Home.


As a result of the insulating properties of MAXRaft®, any concrete poured on top of it takes a bit longer to cure than concrete in traditional slabs. This extended curing results in a stronger concrete floor, which is more crack resistant than traditional methods. If you are using polished concrete floors within a house, MAXRaft® can help lower the possibility of unwanted cracks ruining a beautiful finish. We recommend Multiform's Ultrafibre 500 be used in conjunction with MAXRaft®.

As seen in the iso-thermal analysis above, MAXRaft® helps retain heat in the foundation and thus leads to a higher temperature at the junction of wall and slab when compared to traditional methods. This higher temperature reduces the likelihood of moisture condensation building up in these corners, and thus avoids the buildup of spotty mold in these corners.