Solargon Safety:

Polyurethane Insulation,
Structural Insulated Panels,
Fire Resistance and
Understanding the ASTM Rating

Many home and building owners are understandably concerned about fire safety. Fire damage is one of the greatest threats imaginable to a home or building, so fire prevention and fire resistance are critical features of any home or building. This web page is intended to provide you with a great deal of information about how Solargon structures are designed and built to withstand fire damage. We have a lot of ground to cover, so please bear with us as we present a number of different topics. Feel free to read up on only those aspects which interest you. But we do encourage you to check out the various links provided below, since those links will provide a great deal of additional, third-party information.


A Solargon is assembled with a system of construction components, known as Structural Insulated Panels (SIPs). While SIPs are a huge topic in and of themselves, on this page we're going to focus exclusively on their fire resistance.

As we've detailed on other pages, SIPs are panels made by sandwiching a polyurethane foam core between two sheets of OSB. From a fire performance point of view, an SIP panel has a variety of tasks to perform during a fire, such as resisting flame spread, resisting thermal damage, and resisting physical deformation resulting in structural failure.

The organization which conducts that testing, and which publishes performance criteria for a wide variety of industries (including the construction industry), is known as ASTM International. A discussion of ASTM's varied duties and services is beyond the scope of this discussion, but you may visit their website and read all about them by clicking here.

In the context of fire testing SIP panels, ASTM has several types of testing. One type of testing looks at individual materials, in this case the insulation foam or the OSB panel, to measure how they react to flame spread, thermal damage and structural integrity. A second level of testing is to look at the SIP product as a whole, to see how the product performs as a unit when exposed to flame or fire. For instance, how long does the OSB resist thermal damage before heat reaches the form core? Does heat buildup result in a weakening of the bond between the OSB and the foam core? Finally, ASTM tests what they call assemblies, which are combinations of products found in standard construction, such as floors, walls, ceilings, etc. For instance, how long would it take for a fire at 550C to burn through a wall composed of gypsum wall board over and SIP panel, until the panel was compromized and could no longer support the roof?

After testing the ASTM releases standards for each component, product and assembly, so that architects, contractors, home owners, and building maintenance professionals will know how each material, product or assembly will behave in a fire, and how best to use those materials to minimize fire damage.

For Solargon structures and SIP buildings in general, the two most relevant ASTM standards are ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials and ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials.

Those tests describe a component, product or assembly's performance results during fire testing. One common way to quantify those results is to describe the minimum amount of time elapsed before a component, product or assembly suffered damage sufficient to compromise its performance. For instance, how long would an OSB board resist thermal damage before the foam would be directly exposed to heat and flame? How long before a wall would buckle? For simplicity, those results are condensed further into hourly rankings, for instance, a 1 hour rating vs a 2 hour rating vs a 3 hour rating. Those hourly ratings are also expressed even more simply as Class 1 or Class A for a 1-hour rating, Class 2 or Class B for a 2 hour rating, etc. While this system of ratings has drawbacks and critics, it has been the method of choice for making material comparisons.

Thanks to the ASTM's testing efforts, municipal districts around the country and around the world have begun writing ASTM standards into their building codes. For instance, residential housing materials must meet certain performance codes, based on expectations for how quickly people could evacuate a home. Businesses and factories must meet other codes, sometimes more stringent codes, because of the higher density of people per building, and because of the time required to evacuate. Hospitals and schools must meet even more stringent codes because children and/or the sick and infirm would need even more time to evacuate.

In this context, then, we can now read the ASTM standards with a more educated eye. The ASTM E119 standards indicate that the Solargon SIP panel is a Class 1 material, which means that it can resist fire damage for approximately one hour before catastrophic damage would occur. One hour is generally considered perfectly suitable for residential buildings and most small commercial buildings, since most people can evacuate small buildings very comfortably within a one hour timeframe. But you should check with your municipal construction authority to ensure that any building you have in mind will meet your local code requirements. Any reputable local builder, architect and contractor will also have that information.


For more information about ASTM International, please visit their website at www.astm.org. Their standards are typically available in print at larger libraries, or you can download them (for a fee, payable to the ASTM) from these links:
ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials
ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials
Their full library is available here: ASTM Current Standards Reference

For more information about structural insulated panels in general, please visit www.sips.org.

To read a short article about SIP performance in fires, you can visit their technical article on that topic by clicking here.