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An A-Z of SIP Panels

Updated: Aug 30, 2023


Wellington Builders | Design & Architecture Services | Eco-Friendly Design | High Performing Home | Structural Insulated Panels | Energy-Efficient Home

Man reading instructions, while leaning against SIP panels

Structural Insulated Panels (SIPs) have become quite well recognised in the NZ market. Built of two panels sandwiched together (usually OSB) with an insulated inner core (either expanded polystyrene (EPS) or polyurethane (PUR)), SIPs can be used for walls, flooring, and roofs.

The following is an ‘A to Z’ of our SIPS:

A – Air-Tight

The solid panel means they are air-tight and prevent the uncontrolled transfer of warm air inside the house from escaping, and cold air from outside entering the building. SIP homes are mechanically ventilated to allow the house to breathe in a controlled way. (See “I” for more information about air quality.)

B – Budget-Friendly

Because less time is spent on the construction of your home, and less ongoing energy costs, SIP homes can be much more cost-effective than a traditionally built home.

C – Cladding

When it comes to exterior cladding, the panels can be finished with any cladding you would use on any conventional home such as ply, standard timber profiles fibre cement products, plaster finishes, or stone/brickwork finish.

For the interior walls, some people prefer to leave the panel exposed (bear in mind though, that the black printed mill markings will be visible. For some, this is part of the charm!). You can otherwise use plasterboard or ply to finish the walls.

D - Durable

SIPs are incredibly strong. The structural characteristics of SIPs are similar to that of a steel I-beam (a load-bearing steel beam that is shaped like the letter I). In effect, they provide double bracing to the wall. Also, they are bonded and nailed at all joints which results in less movement and therefore no creaking underfloor.

E – Earthquake Tested

BRANZ has been conducting tests recently in New Zealand to see how SIP panels fare during earthquakes. The tests have proved to be very satisfactory showing that not only are the panels able to withstand the force of an earthquake, but they have a unique ability to take the shock out of the movement by allowing some non-permanent flex in the structure. This is called “ductility”.

F – Fire Tested

Although SIPS are made of combustible materials, our manufacturers have tested their products to prove their fire retardancy. The skin of the panel protects the core for a long period of time and because there is no free airflow within the panel, they tend to extinguish any flames by choking the air supply.

G – Greenhouse Gas Emissions Reduced

Analyses on the life cycle of a SIP have shown that they have a tremendous positive environmental effect by reducing energy use and greenhouse gas emissions throughout the home’s life cycle. Building with SIPs means building with the future in mind and leaving less carbon footprint for the generations to come.

H – High Performing

SIPs are a key contributor to a high-performing building system. Simply put, a high-performing home means it produces as much energy as is used and is therefore incredibly energy efficient. 40% of a home’s energy consumption is related to heating and cooling. However, the thermal qualities in SIPs result in fewer costs spent due to the consistent temperature maintained all year round.

I – Indoor Air Quality

A SIP home provides more control over air quality due to its air-tight building envelope. Controlled air ventilation filters out contaminants and allergens, providing a comfortable living space. The incoming air is also dehumidified which restricts mould growth. For more info on ventilation systems for SIPs, read this blog.

J –Joins and Junctions

The airtightness and durability of a SIP are due to the sealing of all panel joins and penetrations with compatible air-sealing products. Air sealing tapes, adhesives and pipe and cable sealing grommets are installed at all the joins and penetration locations.

K – Knowledge

SIPs have been around since the 1930s, when the concept was created in Wisconsin, USA. The Forest Products Laboratory started experimenting with plywood and hardboard sheathing. This product has and is continuing to be developed to this day. (For more on the development of SIPs, see “U”)

L – Lightweight

Although incredibly strong and durable, SIPs are also very lightweight (approximately 25kg/m2). This makes them easy to install on-site.

M – Maximum Insulation

SIP panels provide maximum insulation without the loss of internal living space. The solid panel of polyurethane PU or EPS (expanded polystyrene) sandwiched between the interior and exterior sheets of strand or plyboard ensures that the building is heated evenly throughout, reducing thermal bridging that is created by standard stud-framed walls. For more information about EPS and PUR panels, check out the downloadable resources here.

N – New Zealand Building Code

All our panels are certified to meet the building requirements of the NZ Building Code. Our panels not only meet this requirement, but they exceed it.

O – Options

Your options are endless when it comes to the design of your SIP home. Every SIP home built by Green Abode is designed according to the client’s preferences, meaning no two houses are the same.

P – Performance

The main difference between a traditionally built home and SIPs is its performance. In 30-40 years, SIPs will still be performing as they did on the day they were built, where the framed house will have lost its’ thermal performance from slumping batts and air currents.

Q – Quick Assembly

Because SIP panels are pre-fabricated at the factory, the assembly time on-site is much faster. Statistically speaking, the structure usually goes up 55% faster than a traditional timber-framed house.

R – R-Values

Whether built with EPS (Expanded Polystyrene) or PUR (Polyurethane), the R-values of SIP panels are much higher than building a traditional home with timber. They start from R2.8 and increase up to R9.4, depending on the type of panel being used.

S – Services

Some panels come with standard holes within the core of the panels for cables to run through. Electricians use flexible fibreglass rods to insert cabling which doesn’t react with the polystyrene within. We normally create a cavity to run the cables inside so they are not locked inside the panels. Plumbing pipes must be installed within standard timber framing and not through the core of the panel.

T - Thermal Performance

The thermal performance of a SIP home is superior to a traditional timber home, due to the solid core sandwiched between the two-ply or strand board panels.

U – Usonian Houses

The famous architect Frank Lloyd Wright used SIPs in some of the houses he designed in the 1930s and ’40s. When one of his students, Alden B Dow, (son of the founder of Dow Chemical Company) created the very first foam core SIP in 1952, he took SIPs to a whole new level.

V – No VOCs

The adhesives that are used in the production of SIPs do not contain any measurable amounts of volatile organic compounds (VOCs) that can be harmful to occupants.

W – Warranty

Our SIPs come with a 20-year warranty on the panel manufacturer for delamination and a 50-year warranty

X – No Waste

Because SIPs are pre-manufactured in the factory according to the architect’s design and then shipped to the site, there is a lot less construction waste. According to some statistics, there is up to 60% less wastage compared to traditional timber homes.

Y – Yearly Inspection

We recommend inspecting the external cladding and roof on a yearly basis to repair any damage or deterioration to prevent any water ingress.


SIPs are highly effective at blocking out high-frequency noise. Good night’s sleep, here we come!

So you see, SIP homes really are all that and then some! However, if you're still not sure about whether a SIP home or a traditional timber home is best for you, this blog post compares the construction process for each. Check it out!

If you would like to discuss your SIP home project, we would love to chat with you. Please contact us by calling 0800 368 470 or by completing the “Contact” form here.


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