Structural Insulated Panels, or SIPs, are constructed of an insulating foam core that is sandwiched between two panels of structural board. These panels are custom made in factories and light-weight while structurally strong, consequently making them popular within modular construction.
Once the building design has been completed SIPs are manufactured off-site and then transported to site and assembled. Each panel is designed with connections to fit into surrounding panels.
A SIPs panel has the benefit of being extremely structurally strong and combining several elements of a building; studs & joists, insulation and vapour/air barriers. Because of this they can be used as exterior walls, interior walls, floors, and roofs. Their structural strength also means that (depending on dimensions) SIPs roofs can span from wall to ridge beam without use of conventional trusses, creating much more internal space - this potentially means adding 1-2 extra bedrooms to a home!
Below: The composition of SIPs and a typical method of connecting panels
Benefits of building with SIPs
- Energy efficient - the insulated core of panels provide even insulation with little cold bridging and extremely low U-values. OSB, which is usually the material that makes up the 2 faces of the panel, is also a higher performing insulator than concrete, steel, or brick. Airtightness levels are incredibly high due to solid insulation core and the interlocking of the panels. All these attributes mean that SIPs is an ideal method of construction for Passive Houses - buildings that meet the strictest standard for energy efficiency.
- Off-site manufacture - panels are built to order meaning easier assembly and less waste. This also mitigates any of the typical potential delays on site due to weather or inefficient labour.
- Build time - pre-designed and manufactured panels mean that construction is very straightforward and can be completed quickly by a less-skilled workforce - think under 2 weeks on site for a new build 2 storey home.
- Lightweight - panels are relatively light compared to their size and can be maneuvered around site very easily.
- Savings - there are many areas where using SIPs can save money - spending less time on site with less equipment hire in the short term, and reduced energy bills in the long term.
What to be aware of
- Upfront cost - the upfront cost of materials is higher than traditional methods, though this is usually offset by savings further down the line. In the short term there is less time and money spent on site and labour. In the long term, energy bills are much lower due to the energy performance of the completed build.
- Moisture resistance - panels can be damaged by moisture so in some situations it may be necessary to use panels made of fiber-cement or treated with an anti-moisture coating. Of course this comes at an added cost.
- Ventilation - SIPs are incredibly air-tight resulting in the needs for a mechanical ventilation system in order for adequate air exchange.
- Design and coordination - panels are bespokely made based on the design of the building and careful coordination is required to ensure correct sizes and openings, as well as cutouts for services. Designing with the standard panel sizes in mind will also result in reduced costs and waste.
- On-site modifications - increasing opening sizes is simple enough, but doing the reverse will be much more complicated and costly. It is therefore imperative to use a designer familiar with SIPs who can coordinate well with the SIPs manufacturer.
SIPs at Yelo Architects
At Yelo Architects we have found that SIPs has been the perfect solution for some of our projects. In one case we were required to create an additional floor of new apartments on top of an existing residential block with minimal disruption to the residents on the floors below. SIPs allowed us to create add 6 apartments quickly and with relatively little disturbance. Due to the lightweight nature of the panels and their structural strength it was not necessary to reinforce the structure of the existing building to cope with the added weight.
Below is a before and after of the build, with the plan of the added floor.