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Wednesday, November 27, 2013

Structural Insulated Panels- Save Money on Energy

What Are Structural Insulated Panels (SIPs)?

Structural insulated panels (SIPs) are a construction material that replaces traditional framing, insulation, and sheathing for walls and roofs.  The Structural insulated panels consist of a sheet of oriented strand board (OSB) or plywood on the outside with a layer of rigid foam insulation in the middle and another layer of OSB or plywood on the other side of the foam insulation.  The result is a panel that is structurally very strong and that has excellent insulation properties.  The R-value of the SIPs can be increased by using a thicker layer of rigid insulation.  The thickness of structural insulated panels typically ranges from 4.5 inches to 12.25 inches depending on the SIP manufacturer.  The R-value of panels of this thickness typically ranges from R-16 to R-48.

Structural Insulated Panels- A layer of structural sheathing, a layer of rigid foam insulation, and another layer of structural sheathing
Image Source: Dr. Penny Pincher

What Are the Advantages of Structural Insulated Panels over Traditional Construction Methods?

One advantage of SIPs is that they provide an airtight envelope for your building.  This reduces cold air from coming in during the heating season, and improves the energy efficiency of a building.  Since the SIPs are manufactured indoors in a factory setting, the quality and consistency of SIPs is very good.  Traditional wall construction may leave rounded corners and gaps that allow air flow.  Fiberglass insulation that is used in traditional construction loses some of its R-value at lower temperatures due to convective air currents in the insulation.  SIPs do not lose R-value at low temperatures.

SIPs can be delivered that have chases for electrical wiring in the rigid foam layer.  This eliminates the need to drill through studs to route wiring.  SIPs come in various sizes ranging from 4 foot x 8 foot panels up to 4 foot x 16 foot panels to facilitate a variety of building plans.  SIPs can be used in wall construction and in roof construction.

SIP construction usually results in buildings that are strong, quiet, and energy efficient.

Do Structural Insulated Panels Cost More Than Traditional Construction?

The material cost for SIPs tends to be higher than the material cost for studs, fiberglass insulation, and sheathing.  However, the labor cost may be lower since the panels can be installed quickly, and there may be less material waste since the panels can be ordered in the desired sizes.

For a rough idea of the cost of SIPs, you can buy a 4 foot x 8 foot SIP that is 4.5 inches thick for about $125.  A panel of this thickness provides an insulation value of R-16.  You can get a panel 8.25 inches thick that provides R-32 for $150.  Different manufactures of SIPs use different types of material and different quality material, so it is useful to check structural insulated panel specifications and prices from more than one manufacturer.

The energy savings from using SIPs may offset any increased cost of construction.  The R-value and vapor barrier qualities of SIPs are considered to be very superior to traditional construction.  Since the interior of the SIP consists of a solid material, there is no opportunity for air leakage or convective air currents though the structural insulated panel.

Structural Insulated Panels at a Construction Site: R-14 and R-18 SIPs
Image Source: Dr. Penny Pincher

What Are the Disadvantages of Structural Insulated Panels?

As with any new technology, SIPs cost a bit more than traditional building materials.  Another drawback is that it may take some work to find construction contractors who are experienced with SIPs.  There are some special tools and methods required if you need to modify SIPs on the job site.

There are some considerations for installing cabinets into a structural insulated panel wall instead of a traditional wall with studs.  Plywood may need to be attached to the SIP wall behind the cabinets, or additional fasteners may need to be used to attach cabinets directly to a SIP wall.

For SIP roof construction, some asphalt single manufacturers will not honor the warranty if singles are installed directly on a structural insulated panel roof.  The roof can get slightly hotter and may reduce the life of the shingles.  There are construction techniques to add a cool layer above the SIP, or you can use a different roofing material to avoid asphalt shingles.

Structural Insulated Panel Recommendations

  • Consider SIPs for your next construction project to reduce energy costs
  • Get an estimate from a contractor who has experience building with SIPs
  • Structural insulated panels are one of the preferred construction methods for building super high energy efficiency homes and commercial buildings

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1 comment:

  1. Do you know which companies in NZ manufacture these panels? I've heard there is a company in Nelson but I haven't been able to find them anywhere.
    Cheers, murray