Insulation is one of the key components of any energy efficient home or commercial building. With heating and cooling accounting for 50 percent of energy use in the average home, the type of insulation you choose can save thousands of dollars in utility bills over the life of your home.

What Are SIPs?

SIPs are the 21st Century Building Material


Galvanized painted SIP with Slip Joint Connection by Precision Foam Fabricators

Structural insulated panels (SIPs) are high performance building panels used in floors, walls, and roofs for residential and light commercial buildings. The panels are typically made by sandwiching a core of rigid foam plastic insulation Expanded Poly Styrene (EPS) between two structural skins of galvanized metal, aluminum or oriented strand board (OSB). Other skin material can be used for specific purposes. There are SIPs made from OSB sheathing and metal skins with injected-in Polyurethane foam. They are generally more expensive for similar R-values. SIPs are manufactured under factory controlled conditions and can be custom designed for each home. The result is a building system that is extremely strong, energy efficient and cost effective. Building with SIPs will save you time, money and labor.

ACME Panel Company photo

Not SIPs as defined by SIPA but ISP (Insulated Structural Panels)

Building since the late 1980’s Greenstone Structural Solutions combines the best materials with the best technology to create the most logical method of building tight, low energy homes and commercial structures that are compatible with all architectural designs.


The Greenstone technology utilizes galvanized steel and EPS to achieve a composite panel for exterior, interior and below grade walls, interior partitions, floors, and roofs. The panel can also be used for high-rise in-fill applications. Greenstone is approved for residential, commercial and industrial applications.


The Greenstone Solution is a unique patented process utilizing the power of composite technology. Greenstone panels start with opposing double steel frames which are bonded with Expanded Polystyrene (EPS). The manufacturing process results in a thermally broken light weight building product that provides structural framing, insulation, and a vapor barrier in one. Panels are seamlessly assembled on site in four foot sections. Rough openings for doors and windows are framed during the manufacturing process. Each Greenstone building is designed in-house for your project.

Greenstone panels are manufactured in a controlled factory process. Each panel is inspected, measured and labelled. This assures quality control along with third party inspection services and compliance with building codes.

Some projects/regions have additional requirements for high wind load, heavy snow loads, high seismic activity, or any combination of these. Greenstone panels can be engineered to meet these additional requirements effectively.

Greenstone technology has been the primary structural system in over 70,000 projects around the world in the past 30 years. The technology has been approved for use in all climatic regions.

Greenstone Structural Solutions Green Acres Colony Housing Units

Greenstone Structural Solutions Green Acres Colony Housing Units

Are Structural Insulated Panels More Expensive?

Building with SIPs or ISPs 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 or ISP construction.

SIPs or ISPs are a perfect match for log home roofs. They far outperform standard 2x roof framing with batt insulation and/or spray foam insulation. They are installed quickly and can be the finished ceiling when combined with 1×6 or 1×8 T&G boards. They require only two trades to finish; one set-up for Finish Carpenters and Electricians. A standard 2x built roof system requires the Framing Contractor to install the 2x’s and the roof sheathing; an Insulation Contractor to insulate the roof, a Sheet Rock Contractor to install the required sheetrock, Finish Carpenters to install 1×6 or 8 T&G and Electricians; all of which takes more time and leaves your home open to the weather for a longer period of time. Both methods require the same finished roofing.


 R- Values in the Real World

Insulation is one of the key components of any energy-efficient home or commercial building. With heating and cooling accounting for 50 percent of energy use in the average home, the type of insulation you choose can save thousands of dollars in utility bills over the life of your home.

Insulation is rated by R-value, which measures a material’s thermal resistance. An insulating material with a higher R-value forms a more effective thermal barrier between the outside temperature and the conditioned space inside the home.

But R-value doesn’t tell the whole story. Laboratory tests that determine R-value have little resemblance to how insulation actually performs in a home. When real world factors such as air infiltration, extreme temperatures and thermal bridging are present, field-installed fiberglass insulation can lose more than half its R-value. Research has repeatedly shown that SIPs provide continuous insulation that will maintain its stated R- value for the life of the home and outperform fiberglass insulation every time.

Thermal Bridging

When field installed insulation is measured in the laboratory, the test only measures the insulation itself, and not the other components that make up the wall or roof system.Wood framed homes rely on dimensional lumber, referred to as studs or rafters, at regular intervals to provide structural support. Lumber forms a bridge from the outside of the home to the inside of the home where heat can pass through by conduction. This process is known as thermal bridging.

Another issue with field-installed insulation is the installation itself. Fiberglass must be installed between the rafters and cut to fit around chimneys, skylight openings and wiring. This process can never be perfect and leaves gaps where there is no insulation at all.

Oak Ridge National Laboratories has led the building industry in defining whole wall R- value, an increasingly popular metric that tests the thermal resistance of an entire wall section. A 2×6 wall with R-19 fiberglass insulation turns out to be R-13.7 when the thermal bridging of rafters every 24 inches is considered and less where 16” rafters are used. When considering common batt installation procedures and thermal currents, conduction and convection within batt insulation tests show the performance drops to R- 11.

Building with SIPs or ISPs does not require any insulation to be installed in the field. There is no dimensional lumber in a Metal SIP home exterior wall. There is very little dimensional lumber required to build a OSB SIP home because SIPs are structurally sufficient. ORNL tests prove that SIPs maintain their full R-value in whole wall testing.

Precision Foam Fabricators photo

 The Effect of Air Infiltration

The effort to maintain a constant and comfortable temperature inside your home is hampered by two forces: conduction and convection. Conduction is the transfer of heat through a solid material, which is what insulation is designed to prevent. Convection is the transfer of air through gaps in the walls and roof of the home. Outside air leaking into the home, or air infiltration, is responsible for 40 percent of heat or cooling loss in the average home.

Fiberglass insulation does not protect against air infiltration, as shown in a comparative test conducted by Oak Ridge National Laboratories. Researchers built two identical 2,600 sq. ft. homes, one made of SIPs and one with conventional wood framing and fiberglass insulation. The SIP research home was five times more airtight than the wood-frame home when measured by a blower door test.

SIPs not only serve as a framing and insulation material, but also as a code compliant air barrier. SIP homes have routinely tested two to three times more airtight than wood frame homes with fiberglass insulation. When Sip roofs are combined with fully kiln- dried log walls the results are similar to a full SIP home.

Air infiltration can cause more problems than just higher utility bills. Air that passes through fiberglass insulation often carries moisture. This can cause unseen mold growth in wall cavities and overall poor indoor air quality that can lead to health problems for occupants.

 Precision Foam Fabricators photo showing 4” wall and 6” roof
SIPs with 1 ½” Hat Channel creating 1½” space for electrical
box and wiring with drywall attached to Hat Channel

Laboratory versus Real World Conditions

In the U.S., the R-value of insulation is determined using a standard testing method called the guarded hot plate test. This test is conducted in a controlled environment, where there is no air movement, at a temperature of 75°F.

Studies conducted by the Department of Energy’s Oak Ridge National Laboratories show that as outside temperatures get colder, the R-value of fiberglass insulation decreases. Using a full scale climate simulator, ORNL tested loose-fill fiberglass attic insulation rated at R-19 at a variety of temperatures. When outside temperatures dipped to -8°F, the R-19 insulation performed at R-9.2. What is more surprising was that infrared imaging revealed convective currents inside the fiberglass insulation. Warm air from inside the house would rise through the insulation, lose heat by coming in contact with the cold attic temperatures, and drop back through the insulation, forming a convective loop of constant energy loss.

In contrast, the rigid foam insulation used in SIPs and ISPs actually performs better in colder temperatures. Expanded polystyrene at 1 lb nominal density with a stated R- value of R 3.9 per inch at 75°F was tested at R-4.2 at per inch at 50°F and R-4.4 per inch at 25°F. More importantly, because all types of SIPs have solid insulation completely enclosed with metal or wood sheathing, they are not subject to any convective currents like fiberglass insulation

Benefits of SIP’s and ISPs:

  • Use with all types and designs of homes including Log, Timber Frame, Mountain, Arts and Crafts,  Craftsman and Modern.
  • Up to 60% energy savings vs. 2x wood studs and rafters and 69% energy savings vs. steel studs according to Federaltest data by Oak Ridge National Laboratory.
  • Metal SIPs require 100% less and OSB SIPs require 53% less raw wood material and trees cut versus conventional framed homes, i.e. environmentally friendly materials.
  • Total Quality Control (TQC) with your architectural plans converted to CAD for panels; builder or architect validates plan dimensional accuracy and approves; plus 100% audit of panel dimensional accuracy at the factory.
  • Our panels are all top quality, brand name, certified panels, produced and manufactured here in the USA to the strictest.

Note: Additional savings are achieved when you consider shortened construction loan time, reduction in cost for HVAC unit, and simplified electrical wiring and dry wall installation, which results in lower total project cost.

We offer custom made, green, cost effective,
energy efficient Structural
Insulated Panels (SIPs) and Insulated Structural Panels(ISPs) to build
your home,condominium or commercial construction.
The professionally engineered SIP or ISP panels are sized and cut to
close tolerances to assure easy and accurate assembly
meeting all local codes, including wind and snow loads.
By partnering with other
quality professionals, we can provide engineering, design,
help with window selection, solar,
HVAC specifications, and assistance in receiving Federal
and state tax credits. We can even assist you
attaining a construction loan and your permanent loan.

                                       ACME Panel Company photo

Richard Melius
Strongwood Carolina Log Homes, LLC
1958 Lake Drive Winston Salem, NC 27127
[email protected]