Why Use Structural Panels (SIPS)
                What are Structural panels (SIPs)?

SIPs are high-performance building panels for floors, walls and roofs in residential and commercial buildings. Each panel is typically made using expanded polystyrene (EPS), or polyisocyanurate rigid foam insulation sandwiched between two structural skins of oriented strand board (OSB), but other surfaces are also available to meet your needs. The result is a building system that is very strong, predictable, energy efficient, and cost effective.

   What R-values do SIPs have?
The R-value of a SIP varies depending on the thickness and type of foam core used. According to a study by Oak Ridge National Laboratory, the "whole-wall" R-value of a wall with a 3-1/2" EPS core is 14 compared to 9.8 for a 2"x 4" wood framed wall insulated with R-11 fiberglass insulation. When the performance of the whole wall system is considered, SIPs perform better than traditional systems because they are manufactured in a controlled environment characterized by uniform fabrication of components without gaps or air pockets. They are also designed for efficient field installation that reduces air infiltration, and there are few thermal breaks or penetrations in the panels that are typical of wood frame construction.

    How do SIPs compare in costs?

Building with SIPs generally costs about the same as building with wood frame construction, when you factor in the labor savings resulting from shorter construction time and less job-site waste.

Other savings are realized because less expensive heating and cooling systems are required with SIP construction.

     Why do SIP homes outperform others?
SIP buildings are vastly more energy efficient, stronger, quieter, and more draft free than other building systems, such as stud framing with fiberglass insulation. Fiberglass is sometimes used for furnace filters because air moves through so freely. Rigid insulation is used as solid component insulation in almost every industry for its inherent efficiency and lack of air movement. These attributes are built right into a SIP building. Less air leakage means fewer drafts, less noise, lower energy bills, and a much more comfortable indoor environment.

     How much more energy efficient are SIPs?
You can slash energy costs by up to 50%. Because SIPs create a tighter building envelope than conventional insulation, your builder can actually reduce the size of heating and cooling equipment. That reduces costs immediately. Better yet, SIPs keep your costs down from season to season, year after year, for as long as you own your home. How are electrical and plumbing installed? In commercial construction, wiring is pulled through conduit. ³Chases² or channels are built into the foam cores of a SIP panel that work like conduit. Electricians use a fish tape and feed the wires through panel chases without compressing insulation or drilling through studs. Typically, plumbing is installed in interior walls and floors, but not in exterior walls. Where exterior wall vent pipes are necessary, chases can be formed in the foam cores. Installing island vents or loop vents is also a common practice and can be found in plumbing codes.

      Why are SIPs more environmentally responsible?
When you build with SIPs, you¹re building homes that can save 50% or more on energy costs when compared to conventional stick frame construction. That means less fossil fuel consumption and less greenhouse gas emissions. SIP technology provides higher ³whole-wall² R-value, tightens the building envelope, and reduces air infiltration. That allows you to downsize the heating and cooling equipment. It¹s the combination of these systems that makes up the technology of a high-performance SIP home. You will also enjoy the green building benefits of less job-site waste, better utilization of material resources, and more environmentally friendly building practices.

      Why are SIPs so much stronger?
SIPs structural characteristics are similar to a steel I-beam. The skins act like the flanges of an I-beam, and the rigid core provides the web of the I-beam configuration. This composite assembly yields stiffness, strength, and predictable performance. Not only do test results show panels are stronger, but natural disasters have proven it time and again. Homes built with SIPs withstood the Great Hanshin (Kobe, Japan) and North Ridge earthquakes, as well as Hurricane Andrew. How do SIPs react to fire? Fire requires three components: fuel, ignition, and oxygen. SIPs have no ³air² within their solid cores of insulation. The fire cannot ³run up the wall² cavity even when balloon framed. SIPs have passed every standard fire test required of wood based or type V construction. A key element of fire safety is protection of the SIPs and any other underlying structure with 15-minute thermal barriers, such as gypsum wallboard.

      How about ventilation?
All advanced technology building systems require mechanical ventilation. These systems bring fresh air into the building and exhaust moisture laden and stale air to the outside. Often, they can be combined with filter systems or other fresh air devices. Not only is ventilation practical, but it¹s a code requirement in many areas. Many heat recovery ventilators (HRVs) are available from your mechanical contractor. See also ventilation.

      How do SIPs save so much labor?
Cutting and fabricating, based on your construction drawings, are done for you in a SIP manufacturing plant. That reduces site labor and time building materials are exposed to the weather on the job site. SIPs are also made in large sizes up to 8 ft by 24 ft so assembly on-site is faster, framing crews are more productive, and the project is ³dried-in² sooner. That means other subcontractors can get a head start on the jobs they need to do.

       What is the structural performance of SIPs?
SIPA manufacturers make their panels to meet code requirements and are listed with the National Evaluation Service, Inc. (NES) or the International Conference of Building Officials (ICBO). These reports have load design charts showing allowable loads for given sizes of structural insulated panels. Contact individual SIPA manufacturers listed on our web site, www.sips.org, for specific data regarding the performance characteristics of the panels they manufacture.

How is wiring done on SIPs?
How is wiring done on SIPs?

  The Structural Insulated panels are both simple and easy for electricians to wire. It does require a small amount of advance planning. Various diameter wiring chases are provided for quick access to panel interiors at both switch height and outlet height. These heights may vary slightly from market to market so be sure ask those questions to get your electrician off to a good start. Panels also usually come with vertical chases that occur about 4' on center. These dimensions, as well as any custom chases, should be verified during the detailing of project shop drawings.

  Type NM-B conductors, as labeled by Underwriters Laboratories, Inc.®, pass UL - 719 which mandates a maximum conductor temperature of 90°C (194°F). The conductor temperatures under normal loads will not exceed 60°C, due to the restrictions on amperage loading and breaker sensitivity. The wiring used for most residential and light commercial structures is commonly referred to as "Romex" is acceptable and widely available with the NM-B designation labeled by UL®.

As with any technical question on wiring, ask your design professional, licensed electrician or code official.

While most panel companies do already have wire chases built into their panels, some don't. In this case you may pay extra to have the chases cut into the panel or as some of the methods shown below.

How do SIPs really react in a Fire?
How do SIPs really react in a Fire?

Manufacturers across North America have proven the fire performance of SIP systems through some of the most extensive fire assembly testing in the construction Industry. The results of this destructive testing allow documentation of SIP performance under rigorous test standards. National standards like ASTM - E119, ASTM - E84 and UBC 17 - 5 have been met by protecting SIPs in a similar fashion as other wood based structures. 'One Hour' fire resistive assemblies are achieved by combinations of underlying structure and protection of that structure by Gypsum Wall Board.

Residential structures are typically required to meet a fifteen minute standard and meet that standard by applying ½" common gypsum over Structural Insulated Panels.

Light commercial and multi-family structures can be required to meet the more restrictive one-hour fire resistive standards. Some of these prescriptive assemblies are listed in the UL® Fire Resistive Assembly Manual, but can be summarized as follows;

1.)  Two layers of 5/8" 'type X' gypsum, attached per the Manufacturers code report, on structural insulated panels with various connections.

2.)  One Layer of 5/8" 'type C' gypsum, attached per the Manufacturers code report, on structural insulated panels joined with dimensional lumber or solid engineered wood products at 48" on center or closer.

As with any fire resistive issue, the local jurisdiction requirements will vary by region, building classification and structure occupancy. You should contact your local building and fire departments to determine those local requirements and involve the design professional to ensure compliance with local and national codes.

Sheating Methods for Timber Frames
Key Benefits of Panels
Structural Integrity - EPS retains its shape indefinitely. It will not shrink, decompose or disintegrate due to age or weather.

  Thermal Stability - The insulating value of EPS does not decrease with age.
  Toxicity - EPS is formaldehyde-free.
  Low Water Absorption - EPS has closed cell structure. Its water absorption level is so low that moisture and the elements will not significantly affect its insulation values.
  Permanence - EPS is an inert, organic material. It provides no nutritive value to plants, animals or micro-organisms. It will not rot and is highly resistant to mildew.
  Flammability - Like many construction materials, EPS is combustible. It should not be exposed to flame or other ignition sources. However, you can expect a building made with SIPs to survive a fire that would completely destroy a "stick-built" home. The panels have passed rigorous fire endurance tests required by national codes, and their solid core construction eliminates the "chimney effect" caused by hollow stud walls.

SIPs approved for use in all seismic zones

In early February 2004, the International Code Council’s Evaluation Service (ICC-ES) approved the use of structural insulated panels (SIPs) on the West Coast where high-risk seismic zones exist (Seismic Categories D1, D2, and E.)  This is good news for building professionals of all types and homebuyers who want a stronger, safer home with the inherent energy savings and comfort homes built with SIPs provide.

Strict new wind codes could provide SIP builders with a new competitive edge.

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Wiring example #5

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