As many of you know. We at Gruen Eco Design are huge fans of SIPs (structural insulated panels)
For those of you who haven’t come across this type of construction. These panels are prefabricated. They consist of a FSC certified OSB3 board on either side of a compressed insulation layer.
The panels are load bearing and can be used for exterior walls, roofs, floors and also internal walls. The panels can come as big as an entire wall, complete with all window and door openings.
The design and house can look any way you want it. You can use any kind of material to finish the exterior. Like render, any kind of cladding, timber, metal cladding, brick or stone. There are no limitations. Same goes for the actual build form. No matter if you are after a traditional or an ultra-modern home.
But what is so special about those panels you might ask?
And are they right for you? Or should you build a stick frame home?
What are the benefits of SIPS?
• faster construction
• Less timber needed
• Recycled content
• Strong, good span capabilities, no bracing needed
• Less wastage and off-cuts
• High R-value (high performing wall system)
• Airtightness – don’t need air membrane, eliminates builder error in insulation
• Can be installed by SIP’s supplier. Ideal for owner builders
Firstly, these prefabricated panels lead to faster construction.
The panels are also lightweight. Which means less money spent on footings. No heavy machinery is required and setting them up is fast.
In fact, a complete house can be at lock up stage within days. A SIPs home uses less timber than a standard stick frame home. Plus OSB timber we use on our projects is recycled. The panels are strong, have a good span capabilities and don’t require bracing.
They are produced off site in a factory. Meaning there is less wastage and off-cut on site.
The panels are energy efficient and offer a much better rating than a standard wall. Wall panels have an R-value of between R2.7 and 4.0 (depending on the thickness). Due to their outstanding performance sips can be used for passive houses as well.
The OSB in itself is airtight. Meaning you don’t need an air tightness membrane. Only the joints need to be taped.
This eliminates builder error in the installation. And minimises the potential damage of the air-tightness layer.
(disclaimer – not all OSB is airtight, hence not all SIP’s panels on the market are air-tight)
The installation of the panels is very easy once you know how it works. The manufacturer can either install the panels or can assist and train the builder.
What are the disadvantages of SIPs?
• Difficulty finding a builder
• Often more expensive than a stick frame home
• Sips may not be the best option for complex roof forms
• Petrochemicals & off-gassing
• Longer lead times
Traditional builders may be hesitant to try something new. Also, many builders put in a security margin if they are not familiar with a product.
Although the product itself is more expensive than a standard stud wall construction. The construction is fast and actual labour cost is minimal. In the end, the construction costs about the same as if you were to build it the standard way or a bit more.
But you have the added benefit of a much faster construction. Which might save you on interest rates and or rental expenses.
Complex roof forms don’t lend itself too readily to sips. Supporting beams are often required.
The insulation is made from petrochemicals. While it is highly energy efficient it is not the most sustainable product. The panels will also off-gas.
Given that the panels are produced in a factory they need to be ordered well in advance. The longer lead times need to be factored in.
What are the advantages with the stick frame?
• Familiarity with builders/carpenters
• Easier to find a builder
• Locally available
• Flexibility to adapt on site
• Perception of being cost effective
What are the disadvantages with the stick frame?
• Many components and room for errors in airtightness and continuity of insulation
• Reliant on builder to construct to standard
• Require airtight layer & bracing
• Chance of condensation issues as insulation is exposed
• Product wastage during construction
• Uses more timber than sips
• Construction takes longer than sips
Whether SIPs are the right choice for you or not depends on a lot of factors.
We always recommend exploring both options. It is worthwhile to discuss your options with a few builders, to determine which option will be best suited for you to achieve your goals.