WHAT ARE SIPs?
SIPs are high-performance building panels suitable for walls, roofs and even floors in residential and commercial buildings. The most common SIPs use expanded polystyrene (EPS) foam insulation sandwiched between two structural skins of steel or oriented strand board (OSB). The result is a building system that is very strong, predictable, energy efficient, and cost effective. Of the two systems, the superiority of the steel system is indisputable.
Steel SIPs (structural insulated panels) are engineered panels made from a dense core of EPS (expanded polystyrene) sandwiched between two exterior layers of factory painted galvalume steel, resulting in a solid one-piece component that provides structural framing, insulation, and exterior sheathing. Approximately 4’ wide, the interlocking panels are strong, light and easy to handle.
The technique of sandwiching a foam core between metal skins has been used in refrigeration technology for decades and many screen room additions and carports have been built using the panels. What is relatively new is their acceptance and approvals nationwide by building departments as a material suitable for home construction. SIP systems are now recognized by all major code organizations and have received the highest seismic rating available from California.
The panels are put through extensive and rigid testing to insure they continue to meet and exceed building code requirements for wind, live and dead loads, racking, and impact. They have been “hurricane tested”, and have proven to be stronger than block or wood frame construction, sustaining only very minor exterior siding damage in winds exceeding 140 mph, with no structural failures.
What are OSB SIPs compared to STEEL SIPs?
Presently, more people are familiar with OSB SIPs than Steel SIPs. They were the first SIP systems readily available, due to the use of inexpensive OSB and workability with conventional carpentry tools. While far superior to conventional framing, they still have some inherent shortcomings.
Unlike Steel SIPs, OSB SIPs must be meticulously sealed against water penetration, requiring messy two part foam sealing and a vapor barrier wrap. Also, the OSB skins are subject to termite damage. Because of their weight, expensive crane rental is incurred at the job site. Due to length limits and dead loads of OSB, the spans are limited without additional structural support.
Steel Skin SIPs eliminate all of these problems. They are light weight, impervious to moisture, termite proof, and offer increased span capabilities.
It is known that the wood framing in a building contributes more to flame spread than any other source except for furnishings. In strict fire testing of the steel skin insulated panels, the metal skins performed extremely well under the intense heat conditions and the fire-retardant expanded polystyrene foam core did not contribute to the spread of the fire.
In addition to the standard required testing, it is important to note that the solid core construction eliminates the “chimney effect” that causes fires to spread quickly through conventionally framed walls.
All testing was done in strict accordance with ASTM and UL testing procedures.
Will STEEL SIP construction hold up to nature’s forces?
YES! Steel SIP framing is stronger than conventional construction, as witnessed in the 2005 Florida hurricane season. Steel SIP homes are designed to meet the newest hurricane requirements and can meet requirements as high as 155 MPH wind loads for barrier islands. That strength also stands up to earthquakes, and Steel SIPs have the highest seismic rating available from the state of California.
What makes STEEL SIP panel construction resistant to damage from hurricane winds?
You probably observed from hurricane photographs that much of the damage consists of partially lifted roof coverings and blown out eaves or soffits. The loss of shingles leads to water entry and drywall saturation. The opened soffit allows the wind to enter the inside of the roof. At this point, the roof is in jeopardy of being torn apart piece by piece as the pressure of the wind acts on the many sheathing panels and framing members looking for a weak point.
With steel SIP construction, none of this happens. The metal skin on the top side of the panel acts as an integral moisture and vapor barrier, blocking any rain damage even if the roof coverings are blown off. The metal skin on the underside of the panel that passes over the wall to create the eave is water proof and virtually indestructible. The integrated SIP system does not permit the wind to grab hold of any element to loosen it and open up the housing envelope.
How much energy savings can be expected?
Steel SIP homes can realistically save 50 to 60 per cent in energy costs compared to frame or masonry homes. HVAC units are downsized for efficiency in SIP homes.
Are the STEEL SIP panels “fire-proof”?
Steel SIP panels are fire-resistant, as nothing is ‘fire-proof’. In a test to show burn characteristics, steel SIP panels obtained superior results in the smoke developed and flame-spread categories. In other words, the steel SIP panels, when exposed to fire, produce almost no smoke and do not allow the fire to spread.
Why is a STEEL SIP panel better than an OSB panel?
There are many reasons.
- •STEEL SIP panels are the structure, insulation and moisture barrier in a single installed unit. OSB panels require an additional moisture barrier.
- •STEEL SIP panels have a tremendous strength to weight ratio, making them light and easy to install without heavy equipment like cranes. An OSB panel is about twice as heavy as a steel SIP panel.
- •STEEL SIP panels are essentially unaffected by insects and other pests. Unless you are purchasing a treated wood panel, the wood in the panel is a food source for pests.
- •STEEL SIP panels interlock without the need for an additional framing member at the joint. OSB panels require a lumber or plywood spline at each joint.
- •STEEL SIP panels have extremely good fire resistance. OSB burns easily.
Also, since all components of steel SIP panels can be recycled, there is less waste on the construction site. OSB panels are not as easily recycled into an equally valuable product.
The FEMA trailers in Louisiana had formaldehyde off-gassing problems. Do Steel SIP panels have this problem?
Off-gas means the components of the construction material emit chemical gases from their manufacturing process into the building environment. Steel SIP panels do not ‘off-gas’ as they are completely inert. OSB panels are made of wood products and adhesives and may emit a number of chemical gasses including formaldehyde.
What about lightning?
A steel SIP home is actually safer than a wood home. The continuous inner and outer steel skins are a continuous ground to lightning and in the event of a strike, it is non-combustible, reducing the risk for fire.
Will my home look different from everyone else’s?
NO! Steel SIP homes look the same inside and out as any other home in the neighborhood. Conventional materials are used for the interior and exterior finishes.
Can homes be built faster using metal panels?
How do Steel SIP homes compare in price to conventional homes?
Steel SIP homes cost about the same as conventional. While material costs may be higher than in a typical framing package, it is more than offset by savings due to speed of construction, reduced waste, and smaller HVAC units.