Structural Insulated Panels, or SIPs, are a type of construction material that is becoming increasingly popular in both the residential and commercial building industries. SIPs in a nutshell, are made up of two layers of oriented strand board (OSB) with an insulating foam core in between. This results in a strong, lightweight panel that can be used for walls, floors, and roofs. 

As we have discussed in a previous article about the reasons why ADU.Works chooses SIP as their construction method of choice over traditional stick-built framing – one of which is that the panels have been shown to reduce heating and cooling costs by up to 50%, in this article we’ll discuss how SIPs are made.


Structural insulated panels, as the name suggests, are made up of two pieces of a type of laminated wood (usually plywood) or an oriented strand board (OSB) as with a layer of insulation in between. They’re available in a range of sizes, (as long as 24-feet) and can be customized to fit the specific dimensions of your project. Given that SIPs are manufactured in factories, this means they can be delivered to the job site ready to install. This saves time and money on the overall construction process.

Photo: Black Bros. Co.

Oriented Strand Boards have been a popular choice as the interior and exterior sheathing for SIPs because of its versatility and load-bearing capabilities. OSBs are formed by adding adhesives and then compressing layers of wood strands in specific orientations. It uses wood from the crooked, knotty and deformed trees that would otherwise go unused. As strands, they are mixed with waterproof resin and interleaved together in thick mats, which are then bonded together under heat and pressure.  This results insolid, uniform building panels, with enhanced features, and high strength and water resistance – making it an ideal product for a variety of purposes, including sheathing in walls, flooring, and roof decking.  It’s also one of the most environmentally friendly building products on the market today. 

The most common type of foam core used in SIPs is expanded polystyrene (EPS). EPS is composed of 98% air, which gives it long-term stability, resistance to heat flow and releasing of chemicals. When it comes to sizes and types of filling, SIPs can be custom-made to meet the specific requirements of a structure. These panels can come in different sizes and thickness along with the type of foam core used depending on the performance property that best fits the project. Some panels are made to be better insulators while others are made to be more constructively tough. The thickness may range from around 3.5 inches up to 11.25 inches, and achieve insulation levels ranging from R-16 to R-49, respectively. 


To form the SIP, the OSB and EPS are then bonded tightly by coating both components with structural-grade glue or adhesives and then pressed together with around 4-6 pound per square inch of pressure for a prolonged time to ensure a fully adhered product.

According to SIPs.Org, the structural properties of an SIP can be compared to that of  a steel L-beam. Because of its unique design, the OSB facers pose as the ridge of the I-beam, while the tightly pressed foam core delivers the web. This allows SIPs to handle compressive loads. As a testament to its structural integrity, SIPs are so strong that they are approved for use in Florida’s strict High Velocity Hurricane Zones (HVHZ) withstanding winds with an excess of 180mph. The load-bearing area of SIPs is equivalent to building with 2 x 10 framing at 16 inches on center, making them a great choice for hurricane-resistant construction. 


Structural insulated panels, or SIPs, are indeed one of the proven ways to build a high-performance home.This method emphasizes a straightforward way to achieve both construction and energy efficiency. In addition, SIPs are easy to work with and can be cut, drilled, and fastened using standard tools. Most importantly, SIPs provide a strong, stable foundation that can help to protect your home against high winds and seismic activity.

With efficiency as one of the top priorities, it’s no wonder why ADU.Works’ uses Structural Insulated Panels. We specialize in building low-cost detached ADUs without compromising or cutting any corners in quality. We are one of the first firms in the ADU industry in utilizing both the benefits of Helical Piles and SIPs simultaneously. With the goal to change the way people in California live, our team is well on its way to help alleviate the housing crisis in the state by providing high quality and sustainable accessory dwelling units to its homeowners.

We want to help you build your new ADU. If you’re interested, please don’t hesitate to book a consultation with us or give us a quick call through our number +1 (650) 227-4810 We’ll gladly discuss the specifications of the Maverick Models and accommodate any question you may have. Our team looks forward to hearing from you.

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