Structural Insulated Panels (SIPs) Vs. Insulated Concrete Forms (ICFs)

Structural Insulated Panels SI Ps Vs Insulated Concrete Forms IC Fs Header

Insulated concrete forms (ICF) and structural insulated panels (SIPs) are two common wall systems used to construct commercial buildings and homes. Both wall systems combine structure and insulation into one unit, which quickens construction and reduces labor costs. However, ICF wall systems have several benefits over SIP wall systems.

ICFs, like Fox Blocks, are more energy-efficient and fire-, mold-, and rot-resistant than SIPs. ICFs also have more design flexibility than SIPs. When choosing between SIP and ICF walls, builders and architects should consider the advantages of ICFs, like Fox Blocks, over SIPs wall systems.

What are Structural Insulated Panel Wall Systems?


Structural insulated panels, also called foam-core panels, structural foam panels, stress-skin panels, and sandwich panels, first gained attention 50 years ago for its high level of insulation, air tightness, and strength over wood-framing wall systems. SIPs are 4- and 8-inch thick rigid foam panels, sandwiched between two rigid sheathing materials.

SIP Foam Panels

Extruded polystyrene (EPS), expanded polystyrene (EPS), polyisocyanurate (PIR) polyurethane, or (PUR) are used to make the foam panels for SIPs. There are similarities and differences between XPS and EPS foam. The foam and sheathing is pressure laminated together. With PIR and PUR, the liquid foam is injected and cured under high pressure.

SIP Sheathing Boards

The most common sheathing boards for SIPS are 7/16 inch thick oriented strand boards (OSB). Other exterior wall sheathing materials include plywood, sheet metal, fiber-cement siding, magnesium-oxide board, fiberglass mat, gypsum sheathing, and composite structural siding panels.

SIPs create straight walls that are structurally sound, air-sealed, and insulated all in one step. Also, because SIPs are factory assembled, wall construction is quick, which reduces labor costs and construction waste. Roofs, walls, and floors of homes and light commercial buildings can use SIPs. However, there are several problems associated with SIP wall systems.

Disadvantages of Structural Insulated Panels (SIPs) Wall System

  • Some SIPs, especially those constructed with plywood, OSB, and composite structural siding panels, do not have adequate fire performance ratings.
  • Durability problems with SIPs can occur, particularly when using plywood and OSB facings. When plywood or OSB gets wet, the walls may mold, degrade, and rot.
  • SIPs have low thermal mass. Materials made of high thermal mass help to stabilize the temperature within a structure, and ultimately save energy and money.
  • Because SIPs are panels, the design of a SIP structure is best coordinated and planned with the panel’s dimensions, without many jogs, bump-outs, or non-90-degree angles. A non-panel friendly design will escalate cos and waste, and diminish the performance of the structure.

Insulated Concrete Form Wall Systems


Insulated concrete forms (ICFs), like Fox Blocks, are composed of concrete sandwiched between two layers of insulated foam. Above- and below-grade ICF construction creates a disaster-resistant, moisture-resistant, durable, energy-efficient and quiet structure. Also, ICF offers design flexibility and is quick and easy to install.

The Disaster-Resistant Advantages of Insulated Concrete Foam

ICF Walls are Fire-Resistant. ICF wall construction creates passive fire protection within a building or home by limiting the spread of fire and smoke. If a fire occurs, ICF also hinders the collapse of the structure. Notably, Fox Blocks ICFs have a fire-resistance rating (ASTM E119) of 4 hours for the 6-inch blocks and 2 hours for the 4-inch blocks.

ICF Walls Protect Against Strong Winds and Flying Debris. ICF wall systems, like Fox Blocks, build a strong continuous path that ensures a building can maintain its integrity against winds above 200 mph. Fox Block ICF walls also can resist damage debris flying over 100 mph.

ICFs are Moisture-Resistant

ICF walls, like Fox Blocks, provide a moisture-resistant solid continuous monolithic concrete wall with a perm rating of less than 1.0. The perm rating is a measure of an assembly or a material ability to limit the amount of moisture that passes through the assembly or materials.

The lower the perm rating, the better. Both the 2018 International Building Code (IBC) 1404.2 and the 2018 International Residential Code(IRC) R703.1 do not require an air barrier or a weather- or a water-resistive-barrier on a solid monolithic concrete wall.

ICFs are Healthy and Durable


ICF wall systems are healthy and durable because they are moisture-resistant and non-organic, which limits the growth of mold and wood rot. Mold and wood rot may occur in the presence of moisture or organic materials, like wood. Mold is unhealthy to those inside the building and wood rot can reduce the structural durability of a building.

ICFs Create a Tight-Building Envelope that is Energy-Efficient

  • High-thermal mass ICFs contribute towards a high-performing, energy-efficient building or home. High thermal mass materials absorb and store heat energy. ICF walls then stabilize temperature shifts within the structure by slowing the rate of heat transfer.
  • Fox Blocks insulated concrete forms exceed ASHRAE/ANSI 90.1 energy code requirements, and create sustainable buildings with superb moisture resistance and energy performance.
  • Fox Blocks also provide continuous insulation with an R-value of 23, which creates an airtight building envelope with better performance than wood- or steel-frame construction.

ICFs Create Quiet Walls

The EPS Industry Alliance (a voice for the ICF industry) reports that about one-quarter to one-eighth as much sound penetrates through an ICF wall compared to a wood-frame wall. Fox Blocks, for example, have a Sound Transmission Class (STC)1 rating of STC 45-50+ and can create a quiet and peaceful interior for a building.

The Design Flexibility of ICF

The strength and flexibility of ICFs allow builders and architects to create any imaginable size or style of a home or building. The ICF forms are easy to cut and shape, including customized architectural effects, such as cathedral ceilings, curved walls, large openings, long ceiling spans, and custom angles.

ICFs are Quick and Easy to Install


ICFs, like Fox Block Series, is fast and easy to install, which saves time and costs. The Fox Block is an all-in-one wall system that combines five construction steps into one, including air barrier, structure, insulation, vapor retarder, and attachment. This feature significantly hastens project delivery by eliminating the need to coordinate multiple trades, while accomplishing all of the wall system’s objectives.

Insulated Concrete Form Vs. Structural Insulated Panels Wall Systems

ICF wall systems have several advantages over SIP wall systems.

  • ICFs are a high-thermal mass material that is air- and moisture-resistant.
  • ICF is more energy-efficient and fire-, mold- and rot-resistant than SIP.
  • An additional advantage of ICF over SIP construction is ICF has more design flexibility and can easily accommodate complex architectural curves and contours.

While ICFs create suburb wall systems, they are not suitable for a roof assembly. The pre-insulated, pre-engineered SIPs are ideal for large spans of roofing and will contribute to an energy-efficient and air-tight structure.

Please visit Fox Blocks for more information on insulated concrete foam vs. structural insulated panels.