Solargon Anatomy:

Structural Insulated Panels

Solargons aren't just pretty to look at. As you have already seen on other pages, they offer a compellingly long list of performance advantages, environmental benefits, and cost effectiveness attributes. But how do they accomplish this? By using structural insulated panels.

This web page will discuss structural insulated panels in much greater detail, for those of you who want to know "the rest of the story". We welcome you to this more technical section of the website, and we hope you'll find here all the answers to your various technical questions.


Basic Information

Structural insulated panels, or SIPs for short, are essentially a three-layer sandwich of materials, which together deliver a much greater sum than their individual parts would otherwise allow. Each SIP is typically composed of a core of insulating foam, enclosed by two sheets of plywood, oriented strandboard (OSB), or other protective surface. In the case of the Solargon, the protective surface is high quality, sustainably produced OSB, and the core foam material is non-off gassing polyethylene, made from recyclable, vegetable-base materials.

For SIP's in general, the three layers are held together via several possible methods: glue, mechanical fasteners, high pressure bonding, or some combination of these methods. Whatever the bonding method, the resulting panel is considered monolithic, meaning that the different layers will not move against each other, and each layer adds strength to the whole. Once bonded, the SIP becomes a rigid panel, capable of supporting immense compression loads, and highly resistant to tension and torsion loads. This is why SIPs are so well suited to residential and commercial building applications - they serve equally well as walls and roof.

But a panel does not make a house. A series of panels need to be joined together in some lockable, airtight method, such that the panels don't move in relation to each other or the ground. How is this accomplished? The simplest SIPs have channels cut in each end, which function as large rabbets (to borrow the term from wood joinery). These rabbets are filled with stub pieces and either fastened with glue or mechanical joiners. More advanced SIPs are pulled together via some method of mechanical joiner or set of joiners, which are built into the end of the panel. For Solargons, each panel is held together with a series of patented cam levers which can be rotated together to lock each panel to the next panel, or unlocked for quick and easy disassembly. The joinery method is one of the major determinants for how quickly a SIP structure can be erected. Solargon's patented system ensures that each Solargon can be erected extremely quickly - mere hours for a 20' model, and less than two days for a 30' model. The joinery system also gives the structure much of its strength. Simpler systems have corner bracing units that essentially allow the panels to join to each other at a 90 degree angle. More advanced systems have rugged corner pieces which not only join two panels at a 90 degree angle, but actually strengthen the resulting assembly by providing reinforcement against shear and torsion loads. Solargon goes one step further with its unique octagonal shape, which is inherently more stable than a square or rectangular shape. The rugged 45 degree angle assemblies, patented cam joiner system and octagonal shape are three of the reasons why Solargons are such stable structures, so resistant to high wind loads, and so suitable for earthquake-prone locations.


Structural Advantages

The Solargon's strength doesn't end there. The advanced bonding method used in the Solargon's panel construction results in a wall far superior to both stud and masonry construction. With a typical stud wall, all the wall's compression, shear and torsional strengh relies partly on the quality of the stud wood, partly on the quality of the sheathing, and - most importantly - on the quality of the bond between them. That bond is typically a series of nails, which may or may not be sized appropriately, located appropriately, and shaped correctly. The best nails for assembling sheathing to wood stud construction are 8 penny ring shank nails. This recommendation comes from studies of houses damaged, or not damaged, by hurricane conditions. Yet ask most contractors if they use ring shank nails when installing sheathing, and the answer is no. Most masonry walls are assembled with mortar which is inherently brittle, and will crack or separate over time, particularly if the wall or foundation shifts for any reason. SIP walls, on the other hand, are light enough yet strong enough to resist all these forces.

Conversely, structural insulated panels are bonded with extremely powerful chemical bonding methods, which not only give greater strength to the panel, but they won't rust, delaminate, pull apart, crack or separate over time. That stability means that SIPs won't fail even under extreme heat and wind loads, and will maintain their structural integrity over a very long span of time. This means that outside walls won't need interior reinforcements, and SIP roofing panels often don't need interior loadbearing walls. So the inside walls can be placed wherever the floorplan needs them to be, or they can be eliminated altogether.


Safety Advantages

The list of SIP advantages over stud construction continues. As many homeowners are already painfully aware, a variety of pests enjoy making their homes in the wall cavities of standard stud construction. Termites and carpenter ants eat the stud wood, mice and rats nest in the cottony insulation, and hornets and wasps build nests in wall voids. Each of these pests come and go through small cracks or openings in the sheathing, and can cause considerable damage. Structures made from SIPs, on the other hand, are much less hospitable to pests. To start with, the building envelope has dramatically fewer possible entry points - the only points of entry come from poorly joined panels or poorly sealed wall/foundation areas. Correctly assembled SIP structures won't have these gaps, and these gaps are easy to find and either correct or fill if needed at the time of construction. The only other possible point of entry is damage to the outside sheathing, which again will not occur with proper maintenance, but are easy to find and fill if damage does occur.

Mice and rats almost never get the chance to gain entry to SIP structures except through extreme negligence of the owner. Insects are harder to detect since they are so much smaller, but even if insects are actually able to gain entry to an SIP wall, their challenges aren't over. Most foam insulation is now impregnated with environmentally friendly boric acid, which is harmless to vertebrate forms of life (such as humans, pets and birds) but which will turn away insects and prevent them from nesting or tunneling.

SIP buildings also offer both fire and flood advantages over standard stud construction. In the case of fire protection, SIP buildings have shown several advantages. First, SIP walls are extremely resistant to flame spread, thermal damage, or structural failure. SIP panels typically carry a ASTM 1 hour rating, which is more than enough for most residential and commercial settings. Interestingly enough, many fires don't last that long in SIP buildings because there's so little air infiltration that the fires starve from oxygen deprivation before they burn that long. Belongings in the house may be damaged from heat, flame or smoke, but the structure will remain intact.

SIP buildings offer both short-term and long-term flood advantages over stud construction. First, because of the superior shear and torsional strength of each panel, SIP buildings are much more resistant to the lateral forces put on them by even shallow floodwaters. Second, because of their chemically bonded structure, water does not have a chance to soak into and ruin the insulation, as it can in flooded stud construction. Third, since there are no voids in the walls, standing water can't pool anywhere and thereby allow the growth of mold, mildew or other disease-causing organisms over time. Damage may occur to the contents of the house, but the structure of the house will still be intact.

For more information about fire and flood risks in SIP buildings, please consult our fire resistance and flood safety web pages.


Cost Advantages

Not all of an SIP building's advantages are from doom-and-gloom reasons. On the contrary, many advantages come to light when looking at the building's long term economic cost effectiveness. Whether this analysis comes before ground is even broken, or after years of service, SIP structures shine when you look at how much they cost. Or, more specifically, how much they don't cost.

Financial savings occur even prior to construction, in the form of extremely efficient delivery options. With standard stud construction, each building component must be delivered separately, often bundled into batches even when not every item in each batch will be used. This extra material must still be loaded and transported to the site, resulting in higher transportation costs. When the building is finished, all that excess material is either thrown away or scrounged. Visit any conventional construction site to see how much waste is involved. SIP buildings, on the other hand, are delivered with only those components required for assembly. The walls are done, the roof is done, the joinery materials are embedded in the panels, and the only thing left to do is lift them into a vertical position, then turn the fastener. No wasted materials laying around.

The labor savings are incredible. Not only are the panels pre-assembled, thus eliminating one entire phase of on-site construction, but each panel attaches to the next in minutes, instead of hours or days.

Even modular homes, which are almost entirely assembled at the factory and only need their large sections joined, can't compete with SIP buildings. Those large sections must be moved from the factory through traffic to the job site, over roads that must meet minimum criteria (and many residential roads don't), via heavy duty semi tractors. Furthermore, many sites are simply too steep or narrow to allow for the modular home sections to be placed and leveled correctly. SIP building components, on the other hand, can be loaded into standard pickup or freight trucks and don't need special permits or clearances prior to delivery. Some days and at some locations, even when money is no object, SIP buildings are really the only viable solution. When money is definitely a concern, SIP buildings start saving you money as soon as the delivery truck starts rolling.


Performance Advantages

The cost savings go well beyond construction day. SIP buildings have such superior insulation compared to standard stud construction, that utility savings can be seen immediately. Whether the interior space must be heated or cooled, that environmental improvement won't cost as much with SIP buildings because the buildings are so airtight and thermally stable. Stud construction, by its very nature, offers dozens or hundreds of thermal bridges between the outside environment and the inside environment, that heating and cooling operations must cycle the air over and over again to compensate. SIP buildings, on the other hand, provide a near-impervious thermal break between the inside and outside, plus offer excellent R value to ensure that heat transmission through the walls and roof are minimized. Heating and cooling systems will cycle far less frequently in an SIP building. Solargons go a step further and allow for natural, passive convection heating to gently cycle the air without human intervention. For environments which require more heating than cooling, the Solargon's window and door placements can gather available sunlight and thus warm the interior passively. For environments which require more cooling than heating, the windows work in conjunction with the operable skylight to allow cooler air on the shaded side of the building to enter, and hot air to be exhausted out the top, thus creating a steady, gentle moving column of air for the freshest possible interior environment.


Environmental Advantages

And now we come to that topic where the Solargon truly shines above all others - its inherent superiority over all other buildings in terms of environmental performance. We have already covered the concepts of passive solar heating and cooling, which by themselves dramatically reduce the Solargon's need for energy from any manmade source. If that was the only advantage, the Solargon would be a triumph. But the Solargon doesn't stop there. Each material in the Solargon SIPs was chosen for its environmental characteristics. The polyethylene foam, for instance, won the EPA's 2004 Stratospheric Ozone Protection Award because it was one of the first commercially available hydrocarbon and HFC-formulated rigid spray systems to serve as an alternative to HCFC-141b. Furthermore, the foam contains no formaldehyde or VOC's, and will not offgas noxious fumes to either the interior or exterior of the structure.

But we didn't quit there.

The SIP's OSB layers are made from the waste product of other wood milling operations, instead of requiring new wood to be milled. The patented cam lever fasteners used to connect the panels require only four or five connector assemblies instead of hundreds or thousands of small metal connectors, which in turn saves both energy (for the metal fabrication) as well as the raw materials which go into the metals. The Solargon's octagonal shape maximizes interior space while minimizing the amount of material required to enclose that space. The skylight reduces the need for interior lighting as well as reducing the need for mechanical heating and cooling, as detailed above. And happily, all this environmental good news comes with a competitive price tag.

Bottom line, SIPs in general and the Solargon in particular do not need exotic materials or designs or solutions, to achieve superior economic, environmental and ergonomic performance. It's just a matter of selecting appropriate materials, and putting them together in appropriate ways, to create a superior Solargon.


Summary

We hope this page has answered your questions about Solargon's structural insulated panels, and their inherent advantages. If you have any questions, please contact us for more information.