SIPs vs. Conventional Framing

Comparing the Wall System

Conventional Framed Walls

2x6 wall framed at 16" o.c. installed with R-19 fiberglass insulation.

EPS Structural Insulated Panels

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 closed-cell rigid foam plastic insulation between two structural skins of oriented strand board (OSB). Depending on the size and needs of the structure, the thickness of the foam is adjusted to increase R-value.

Comparing R-Value Performance

Conventional Framed Walls

R-Value of 13.7.

EPS Structural Insulated Panels

R-Value of 24.7. Depending on the size and needs of the structure, the thickness of the foam is adjusted to increase R-value.

Comparing Thermal Breaks

Conventional Framed Walls

Each stud location represents a thermal short circuit in the insulating barrier, allowing moisture-filled air to pass. When wood 2x6 framing is used, an average 33% of the wall surface is comprised of 2x6 framing that is R-6.

EPS Structural Insulated Panels

EPS SIPs join high performance closed-cell rigid foam insulation to oriented strand board (OSB) or plywood. It averages only 7% of the lumber used in the shell of a building.

Comparing Moisture Effect on R-Value

Conventional Framed Walls

Fiberglass can lose as much as 80% of its R-value when exposed to even low moisture levels, which are common below grade. Moisture leads to wood decay.

EPS Structural Insulated Panels

When exposed to moisture, the R-value SIPs remains constant and will shed liquid water.

Comparing Temperature Effect

Conventional Framed Walls

Fiberglass insulation loses as much as 40% of its insulating capacity when temperatures fall below 20ËšF and over half its R-value below 0ËšF.

EPS Structural Insulated Panels

The thermal performance of SIPs are not affected by changes in temperature.  In fact, studies have shown R-values to improve as temperatures decrease.

Comparing Compression Effect

Conventional Framed Walls

Fiberglass must be fully expanded to work properly.  If it is stuffed into openings or compressed by plumbing or electrical wires, it loses most of its R-value.

EPS Structural Insulated Panels

Electrical wire chases are internal in an EPS panel system.

Comparison of Mold and Mildew

Conventional Framed Walls

Organic wood studs absorb moisture and support mold growth.  Fiberglass insulation also absorbs moisture and promotes mold growth.

EPS Structural Insulated Panels

An airtight SIP building envelope forms the basis of a successful mold control strategy. The extremely low levels of air infiltration in SIP buildings allow for incoming air to be provided in controlled amounts by air handling equipment. Proper dehumidification of incoming air following ASHRAE standards will create an environment where mold physically cannot grow.  In addition to creating an airtight structure, SIPs are solid and free of any cavities in the wall where moisture can condense and cause unseen mold growth.

Comparing Indoor Air Quality

Conventional Framed Walls

Wood building materials and fiberglass insulation are often treated with preservatives and formaldyhyde. Mold and airborne toxins contaminate the indoor air quality.

EPS Structural Insulated Panels

The tightness of the SIP building envelope prevents air from gaining access to the interior of the home except in controlled amounts. A controlled indoor environment is both healthy and comfortable. Humidity can be controlled more easily in a SIP home resulting in a home that is more comfortable for occupants and less prone to mold growth and dust mites. SIP panels have no offgassing and use no formaldahyde.

Comparing Strength and Stability

Conventional Framed Walls

Wood frame construction exceeds strength requirements but egrades over time.  Wood framing members warp and twist as moisture levels vary. Nail "pops" are common.

EPS Structural Insulated Panels

The structural characteristics of SIPs are similar to that of a steel I-Beam. The OSB skins act as the flange of the I-beam, while the rigid foam core provides the web. This design gives SIPs an advantage at handling in plane compressive loads.  SIPs can be engineered for most applications.

Comparing Vapor Control

Conventional Framed Walls

Basement walls must be able to dry.  For walls built below grade, drying typically means towards the interior. Adding vapor barriers to control the moisture actually keeps the moisture from being able to dry properly.  If placed directly against the masonry wall, an impermeable barrier keeps moisture from being able to dry towards the interior.  If installed over the wood frame moisture is trapped inside the wall cavity causing wood to rot and mold to grow.

EPS Structural Insulated Panels

Air barriers or vapor barriers are not required in SIP buildings because properly sealed SIPs create a code compliant air barrier with a permeability rating of less than 1.0 perm. In addition, the foam core of SIPs is solid and continuous throughout the wall, eliminating the convection and condensation issues that can occur in cavity walls above and below grade.

Comparing Insulation Installation

Conventional Framed Walls

The performance of the thermal barrier is dependent in part upon the quality of workmanship.  For fiberglass insulation to work effectively, it must be in continuous contact with its surrounding surfaces on all six sides.  It is virtually impossible for installers to achieve this on a job site.  Even the smallest gap allows air circulation which kills the insulation value.

EPS Structural Insulated Panels

Because SIPs are prefabricated, the amount of additional framing required is minimal. SIPs are always straight and true. There are far fewer callbacks, fewer culling studs, or need to straighten walls. SIPs also provide a uniform nailing surface for both interior and exterior finishing.

Comparing Environmental Impact

Conventional Framed Walls

Wood framing members are produced from trees and treated with preservatives.  Fiberglass insulation is often produced with formaldahyde.

EPS Structural Insulated Panels

Since SIPs are prefabricated in the factory, there is less job site waste that needs to be landfilled. Factory fabrication is done using optimization software EPS recycles factory scrap to make other foam products. Structural insulated panels are one of the most environmentally responsible building systems available. A SIP building envelope provides high levels of insulation and is extremely airtight, meaning the amount of energy used to heat and cool a home can be cut by up to 50 percent.

Comparing Durability

Conventional Framed Walls

Wood frame walls attract moisture, mold,  and insects which eventually leads to wood rot and deterioration. 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.

EPS Structural Insulated Panels

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.
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