Frequently asked questions about SIPs and Smart Panels

NZSIP Smart Panel homes go up much faster than traditionally framed buildings. Statistically, the structure goes up 55 % quicker than a traditional timber framed construction.

Entire wall and roof sections can be put up quickly, with the complete smart building system, you can build a weather-tight, super-insulated floor, wall & roof building shell within a matter of days. Smart Panels are ready to install when they arrive at the job site, eliminating the time needed to perform the individual operations of framing, and insulating stick-framed walls. All you need to do is wrap the wall panels once they are installed to ensure weather tightness.

Smart Panels are manufactured in the following sizes:

  • Standard Smart Wall panel sheet sizes: 1200 mm wide x 2.4m, 2.7m, 3m high.
  • Standard Roof & Floor panel sheet sizes 1200 mm wide x 2.4m, 2.7m, 3m, 3.6m long.
  • All Smart Panels have 12mm Strandboard as standard, we can also use Ply as a panel skin option.

Smart Panels are custom-built to your individual design — these dimensions will not restrict your layout in any way.

Due to the labour savings that can be achieved in faster construction of the building shell; Smart Panels work out at cost parity to 140mm framing but with significantly higher thermal performance and comfort levels. The finished building requires a lot less heating so ongoing running costs are significantly reduced and comfort levels increased.

Structural insulated panels are one of the most environmentally responsible building systems available. A SIP building envelope provides:

  • continuous insulation
  • is extremely airtight
  • allows for better control over indoor air quality
  • reduces construction waste, and helps save natural resources.

Life cycle analysis has shown that SIP homes have a tremendous positive environmental impact by reducing energy use and greenhouse gas emissions throughout the home’s life cycle.

Rigid Closed Cell PolyUrethane Foam (PUR) foam insulation is thermoset into each of our custom built Smart Panels. When cured it becomes chemically inert & will not outgas any harmful chemicals; there is also no formaldehyde in PUR foam. The blowing agent that helps to generate the closed cell bubbles in the foam has Zero Ozone Depletion Potential (ODP) – The Thermal Conductivity of the PUR foam is – 0.019 W/mK-1. Polyurethane foam insulation, due to its non sagging, water-phobic and adhesive qualities it will perform at to optimal levels for the foreseeable life of the building.

The structural characteristics of SIPs are similar to that of a steel I-beam. The skins act as the flange of the I-beam, while the rigid foam core provides the web. This design gives SIPs an advantage when handling in-plane compression loads.

Smart Panels are manufactured in our Cromwell factory. This means we can accommodate any specific engineering requirements relating to the build into a production run. Structural timber and detailing is incorporated into the panel production. By comparison, standard PUR or EPS structural insulated panels are manufactured in standard sizes; need to be cut post-manufacture and cannot incorporate any engineering.

Smart panel span capacity is 3.6m. If longer spans are required support purlins or integrated splines are incorporated into the design. For most applications, SIPs are structurally self-sufficient. In cases where a point load from a beam or header requires additional support, a double dimensional lumber spline or engineered wood spline is field installed at in-plane panel connections. In roof applications, SIPs rely on beams and purlins for support.

As with any build, understanding your design’s engineering requirements is critical to the overall build process. We strongly recommend engaging an engineer as soon as concept plans are completed. The engineering requirement of your design will have a direct influence on the complexity and cost of your build.

SIPs can be engineered for most applications. Detailed information on the structural performance of our Smart Panels is available, please get in touch with us for the latest documentation

SIPs are compatible with almost any building system. Wall panels can sit on a variety of foundation materials, including poured concrete, blocks, or insulated concrete forms. SIPs are sized to accept dimensional lumber and are seamlessly compatible with stick framing.

Smart panels endorse and support the requirements of the New Zealand Building code to use a cavity batten system. This requires all claddings be installed with a drainage gap between the cladding and the weather-resistant barrier.

Internally Smart panels are fixed with a batten and interiors can be finished in any standard interior finish.

Externally, as with conventional building systems — the panels are battened out and can be finished in ply, cedar, thermory timber, titan board or cement board with a plaster finish or stone/brickwork finish.

Direct fixing of cladding to SIPS panels is still undergoing research locally and internationally. There are limited applications where direct fixing is an allowable building solution.

Wiring is resolved in the cavity space between the Smart panel and the internal cladding product. This allows conduit to be added for electrician to chase cabling through. Fixtures are installed through floors, internal walls or internal cavity.

Yes. Smart panels currently meet Council requirements under alternative solution category. Ongoing testing and development means that we are continuously striving for improvements.

Recessed lights should never be embedded in SIPs. Recessed lights can be fitted using an internal ceiling cavity. Many LED downlights are extremely low profile and will fit into a 20 mm ceiling cavity.

The sound resistance of a SIP wall depends on the thickness of the gypsum drywall applied, the exterior finish applied and the thickness of the insulating foam core that is used. SIPs are especially effective at blocking high frequency noise and most homeowners notice the quiet comfort of a SIP home.

Plumbing should not be located in exterior SIP walls because of the possibility of condensation or supply lines freezing in cold climates. During the design phase of the project, all plumbing should be relocated through interior walls and/or floors.

An airtight SIP building envelope forms the basis of a successful mold control strategy. The extremely low levels of air infiltration in SIP buildings allow for incoming air to be provided in controlled amounts by air handling equipment. MVHR systems create an environment where mold physically cannot grow.
In addition to creating a draught free structure, SIPs are solid and free of any cavities in the wall where moisture can condense and cause unseen mold growth.

An airtight SIP building envelope stops all vermin and pests from being able to enter into the building structure removing the issues of mice,rats and nesting birds within the wall or roof cavity of your home.

NZSIP are committed to best practice when it comes to thermal performance: That’s why we settled on polyurethane (PUR) core, structural insulated panels (SIP) to offer New Zealand a high performance solution to our country’s building challenges.
PUR core SIPs have not been widely used in NZ prior to the factory opening and as part of our ongoing work, we have been engaged with third parties to review relevant standards for determining product performance.

The R-value (a measure of thermal resistance) of our panels shows the value of an average panel at manufacture, and the thermal performance over the intended lifetime of the product (typically at least 50 years) reduces to no less than 115mm R3.7, 165mm R6, and 215mm R8 .

When comparing the thermal performance of NZSIP panels with other products please ensure that the information you have also indicates the thermal performance over the intended lifetime of the product to enable a valid comparison.

SIP buildings are extremely airtight and require mechanical ventilation. Ventilation systems bring fresh air into the building in controlled amounts and exhaust moisture laden and stale air to the outside. By limiting air exchange to controlled ventilation systems, SIP homes allow for all incoming air to be filtered for allergens and dehumidified, creating better indoor air quality. Proper ventilation is important in all homes to preserve indoor air quality.

A controlled indoor environment is both healthy and comfortable. Humidity can be controlled more easily in a SIP home, resulting in a home that is more comfortable for occupants and less prone to mould growth and dust mites.


Polyurethane is a relatively new product, roughly around 35 years. EPS has been with us for around 50 years.

Polyurethane is the highest rated insulation in the world. You will find it in most all of your refrigerators, freezers, and even in your personal carry about coolers. Per inch of insulation it has no equal.  

Probably the biggest difference between Polyurethane and EPS is in the manufacturing of these panels. Both products use particle board for covering both sides of their foam, but here is where the similarity ends. In the bonding of the foam the actual polyurethane is used as bonding agent to the board itself. Polyurethane is one of the best glues used in the industry today. Some manufactures of OSB and plywood use polyurethane to bond their products together. When it comes to adhering, the use of polyurethane gives us both an excellent R- value and the strongest bond in the industry. EPS panels use glue spread on both sides of the OSB, and then the OSB is matched together with the EPS, and mechanically held in place and under pressure until the glue is dried.

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