IDEAL House – New Zealand

Project Goals: Certified Passive House, Positive Energy & 8/10 Homestar design. Proudly supported by IDEAL Electrical Suppliers.

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Timber Engineering

Thanks to Paula and her team from Green Being, all our timber engineering is now complete. They have done an incredible job, and can’t thank them enough.

“We chose to use engineered timber I-beams as they offered a cost effective roof span solution at the optimal design depth for maximum insulation coupled with a very low level of thermal bridging. Timber beams were also selected around the building perimeter to ensure we minimised thermal bridging, we had to avoid using structural steel. Engineered wood products gave us the additional strength we needed for the larger spans”. Paula Hugens, Green Being.

Distributed by NZ Wood Products, and then sourced via our local Smiths ITM, we are sourcing several 17C HyneBeams (as pictured below), as well as some 240mm I-Beams for the roof, and some 360mm I-Beams for the garage. We are supplementing solid 240mm timber for the midfloor with a single steel arch (two posts and a cross bar) to support the mezzanine floor. Although we would like to use timber wherever possible, the steel allowed us to reduce the depth of the floor (and reduce overall height of the building) as well as increasing the amount of standard timber versus engineered that we were able to use. The steel will remain within the thermal envelope to avoid any thermal bridging from outside, as it’s an incredible conductor of heat.

Hyne 17c

17C HyneBeam, distributed by NZ Wood Products.

LP I Beam

LP I-Beams, distributed by NZ Wood Products.

Here’s a screen shot of some of the engineering layout.


Full timber engineering for the project can be downloaded here: 20249 Structural Spec Rev2 (1).


Slab Engineering

Thanks to the assistance of Wilton Joubert, we have now completed the last piece of design/engineering – the concrete slab. The architects, Matt and Stephen from S3 are now adding the slab details to the working drawings and we plan to be ready to lodge consent by the end of the week.

We are using a polystyrene pod system, based on the original Rib Raft which was designed by Firth, and incorporating reinforcing bar (EuroSteel) and mesh (Xtra Ductile G500E) from EuroCorp.

The slab has been designed to handle the weight of the solar panels on the roof (40 panels at about 21kg each), in a high wind zone, and load bearing walls that have come about to support the mezzanine floor and wider spans inside.


As the garage is outside the thermal envelope, we have also had to add in a step down to incorporate the extra thickness of the batten and cradle system we’re using to insulate the main slab (above the concrete).


The drawings also show our nib which will run around the outside of the slab edge, again allowing for the batten and cradle system to sit on the inside of this nib.

ImageFull slab documents can be viewed here:

Plans and details


Drainage details

Producer Statement