SIPS PANELS
The Opportunities:
Innovative, high-efficiency design and construction methods for NZ homes have taken methods used for industrial and commercial applications, creating practical options for rapid assembly of highly insulated, airtight structures – Structurally Insulated Panels (SIPs).
What are SIPs?
SIPs are increasingly common for new builds and some renovations, used for walls, ceilings, roofs and floor systems. They are made of an inner core of insulation, sandwiched between two rigid face layers or skins, such as plasterboard, fibre-cement board, engineered wood panels, metal or magnesium oxide board with glass fibre mesh reinforcing. The core materials are commonly polystyrene, polyurethane or polyioscyanurate
The prefabricated panels are usually craned into position on the build site, and assembled with tongue-and-groove joints or overlaps and interlocking fixing systems. There can be solid timber plates running along the top and bottom or spines between the panels to secure them in place. Some SIPs provide for cabling or plumbing within the panel, depending on the type of SIP and materials.
SIPs can be used for structural and non-structural components of the building. The priority with non-structural panels is as thermal insulation in roofs, walls and underfloor.
BRANZ is undertaking a continuing programme of testing SIPs for structural integrity, fire safety and seismic loading:
EQC (now the Natural Hazards Commission) also conducted research on the seismic performance of timber-skinned SIPs, finding that:
SIPs exhibit the kind of seismic performance considered desirable for effective earthquake resistance, including stiffness, strength, ductility and energy dissipation
Damage during cyclic loading was less for the SIPs than most commonly used bracing systems:
Advantages of SIPs include:
Rapid assembly giving a much shorter time the build site is exposed to weather, and a more efficient build process
High insulation properties and thermal performance, giving better energy efficiency
High airtightness levels
Rigidity and strength
Acoustics with noticeable quietness inside the building
Consistent levels of warmth and comfort in the home
One aspect that people need to consider is that SIPs are constructed off-site before assembly, so all critical decisions must be finalised prior to that point.
“SIPs – Structural Insulated Panel – conventional panels could be EPS or polyurethane with OSB board or plywood on the outside, that forms the structure of 1200 mm wide panels which are then put together on site.”
Dan Saunders: Dan Saunders Construction & Ecopanel
“We generally build in a 1200 wide space, could be 2.7 m, 3 m, or 3.2m high – an EPS core which can vary in size – exceed the H1 rule changes – sheathing that is healthy, no chlorides, water stable – remove extra layers of the build process, don’t need extra layers of GIB inside, integrate services into the panels.”
Gary Peters: SelectSIP
“Eco Panel offers an alternative solution. Some people don’t like EPS or polyurethane as an infill for their walls – Eco Panel utilises an older methodology using stick framing with no dwangs, insulation layers go full height – it is a conventional solution to a now problem, being able to build quicker and more efficiently on site.”
Dan Saunders: Dan Saunders Construction & Ecopanel
“Able to span 7.2m in their panels – save on engineering – Codemark approved for council consent processes, fewer building inspections. Eficiency for trades time on site, making the process better.”
Gary Peters: SelectSIP
“If you want to take it a little bit further we’ll do something like SIPS panels. We've done about 6 houses with SIPS panels – done SIPs in my own house so I can live and breathe and tell the story and show people that, which is really helpful.”
Peter Davis: AD Architecture
“The speed of SIPs construction... we spend alot more time in planning, alot of good design practices are put behind it... it eliminates alot of that process on site – by integrating the services, your electrical and plumbing, into the panels, less tradesmen on site.”
Gary Peters: SelectSIP
Some Superhome Partners and Participants have developed innovative panel systems that combine the performance and benefits of SIPs with the use of non-toxic insulation materials:
EQC (now the Natural Hazards Commission) also conducted research on the seismic performance of timber-skinned SIPs, finding that:Superhome Participant Select SIPs – panels are free of volatile organic compounds (VOCs) or chlorides, non-combustible, and non nutrient (will not support mould growth), with a low carbon footprint:“Our building system creates a controllable, airtight, stable interior home environment that is 50% to 70% more energy efficient than a conventional wood-framed home.
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Superhome Participant Hiberna Modular – using custom-made eco-friendly straw panels, made from renewable locally-sourced materials, with low carbon and low VOCs.
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Superhome Partner Ecopanel – using natural, low-VOC and high-performance materials to create bespoke panels where none of the materials are on the Red List of toxic building materials.
The exact components inside an Ecopanel will vary depending on the project, but a typical assembly (from the outside to the inside) includes:
MCA-treated structural battens: Provide airflow and drainage behind the cladding and support the exterior cladding system. MCA (Micronised Copper Azole) is an arsenic-free timber preservative.
Pro Clima Extasana (weather-resistive barrier): A high-performance, breathable exterior membrane that protects the structure from wind and rain while allowing internal moisture to escape.
9mm MCA-treated plywood OR treated OSB board: Forms the rigid structural outer layer of the wall system, adding strength, bracing, and resistance to moisture.
Nelson Pine LVL structural framing: High-strength laminated veneer lumber (LVL) used as the main structural framework of the wall. Manufactured with precise engineering for stability and low waste.
Acoustics with noticeable quietness inside the building
Insulation layer (varies by project requirements)
Some Superhome Partners and Participants have developed innovative panel systems that combine the performance and benefits of SIPs with the use of non-toxic insulation materials:
