Lets Talk about about SIPS

A structural insulated panel (SIP) is a form of sandwich panel used in the construction industry. SIP is a sandwich structured composite, consisting of an insulating layer of rigid core sandwiched between two layers of structural board, used as a building material .

Sips panel.jpg

Some of the arguments for building with SIPS include:

  • Faster construction

  • Less waste

  • High R-value.

  • Integrated Structure

Being open to new technology and innovation, I looked into it using SIPS my own house. I even designed a version of the house for SIPS specifically and then got it priced for construction to compare with a timber framed home of equal performance. Here is what the process taught me about SIPS.

  1. The time saving may not be worth the additional cost of the SIPS products over timber frames. In construction terms, erecting the building structure only accounts for a portion of the overall build program. A site based carpentry team can erect a two storey timber home structure and make it weather tight in around 4 weeks. A SIPS build house claims to achieve this in 1 to 2 weeks. A saving of 1 to 3 weeks over a 6 month build isn’t significant enough to justify the extra cost and complexity of SIPS, especially if you have to wait for a production slot for your panels to be manufactured, checked, delivered to site and erected.

  2. There is limited number of SIPS panel suppliers around which means that there is a lack of competition in pricing. WA for example has two active SIPS panel providers, both of which have their own product composition, module dimensions and installation methods. These suppliers are relatively small without the large economies of scale to make SIPS pricing cost effective overall.

  3. There is a limited number of tradesman with experience in SIPS so it is hard to get a price for construction that isn't loaded with risk. It is not just about the SIPS install itself. Builders, Electricians, Plumbers, Engineers, Air Con Installers are just a few of the contributors to your home that will have to adjust to working with SIPS, and in our building industry unknown factors ring big alarm bells. Every trade that deals with this unknown will want to add time and cost to your project cover the risk.

  4. SIPS works particularly well when the home is designed specifically to the panel sizes in order to minimise wastage. This takes a significant amount of additional time and cost in design phase.

  5. If you do design specifically for SIPS, but later find the cost of building with SIPS is too costly then you are stuck with drawings that should be modified for framed construction due to wall thicknesses and detailing needs are different.

  6. Being a composite structure SIPS structures are difficult to modify later (you cannot simply remove walls or peel back cladding to add extra wiring for example).

  7. SIPS are untested over long periods of time. Some SIP builders use silicon sealant to connect the panels. Over time this will degrade and allow water ingress. A NSW based company using SIPS recently went bankrupt due to a high number of their homes forming mould after installation. Mould in any home is massive issue, but in a SIPS home it is unfix-able. Water may even get inside the skin of SIPS as the home is being erected, but the issues wont arise until much later after the builder has left the scene and the warranty period has expired.

  8. When the water does inevitably get in, the moisture has no way to leave the composite structure. This results in mould and material degradation. The timber framed walls in a Leanhaus are designed to allow the structure to breathe so they can dry out even in the unlikely event moisture does get in down the track.

  9. Sustainability and end of life - The individual materials that make up SIPS (foam, OSB, FC Sheet) cant be recycled due to the foam being bonded to the outside skins. This make recycling the panels cost prohibitive.

A SIPS building should be designed to use the manufactured module size in order to minimise waste.

A SIPS building should be designed to use the manufactured module size in order to minimise waste.

For all the above reasons Leanhaus has rejected SIP based construction in favour of site built timber frames. We can achieve similar levels of insulation with air tightness almost as fast and more cost effectively than SIPS. For the right client and project we will explore prefabricated timber wall panels, but only if makes sense and adds value to the project.

Leanhaus is established to provide the right balance of cost, quality and flexibility based on many years of experience, research and knowledge around design, sustainability and construction.

Feel free to get in touch if you have any questions.