MAXRaft® on TC2, Piles or Expansive Soils

MAXRaft is our solution for an insulated slab being built on less stable ground, in particular the TC2 type ground encountered in Christchurch or when moderately or highly expansive soils are encountered.

Heights of the perimeter insulation can easily be adjusted from our standard options which are 320mm, 340mm, 400mm, 420, 520mm and 620mm .

The MAXEdge perimeter insulation and load bearing thickenings from our MAXSlab® remain similar, ensuring that your perimeter and load bearing walls can be supported while maintaining the thermal envelope around the house.

The infill area of the slab is changed somewhat, engineered to provide stiffened ribs throughout the floor with the additional advantage of maintaining a thermal break around the foundation rather than transferring heat directly to the ground between the ribs where it is lost, as is the case with traditional waffle floors.

Each of these components combine to give you a foundation with an R value between 1.9 and R3 depending on the design. From May 2023 this design is adjusted to work in conjunction with Underfloor Heating where a minimum of R3 is required.  Check out MAXRaft Plus when specifying underfloor heating on soft ground.

For Houses with brick cladding the R-values in our R-value Calculator assume a rebate, however higher R-values can also be achieved with a brick to ground detail found in our downloads section.

MAXRaft meets the requirements of Homestar V5 and is adjusted to meet the requirements of Passive House Certification. 

Download standard MAXRaft PDF, JPEG & DWG files.

Contact us for a MAXRaft quote here.


Product Features

• Suitable for soft ground, TC2, expansive soils and piles

• Standard heights 320, 340, 400, 420, 520 and 620mm (bespoke options available)

• Less time required on site

• Site-specific engineering

• Reliable, proven construction details

• Superior R-values

Engineering (PS1) for consent can be arranged through MAXRaft® or completed by any Chartered Structural Engineer.  We work with a group of engineers who are experienced in designing MAXRaft® foundations and can pre-empt council queries.