Foundation Walls built with Insulated Concrete Forms [Styrofoam (polystyrene) block foundation walls]

The foundation of every building is fundamental in the transfer of all loads throughout a building into the ground.  It also acts to anchor the building’s structure, especially in areas where earthquakes and high winds are a hazard.

Traditional foundations are constructed by pouring concrete into temporary forms which are removed after the concrete has cured.

What Are Insulated Concrete Forms?

Insulated Concrete Forms (ICFs) are a wall building material that are an alternative to traditional wood-frame housing.

Instead of framing the walls with studs, walls are formed using styrofoam blocks.  ICF wall systems consist of foam boards made from expanded polystyrene and integral hinged plastic webs that hold both sides of the boards together.  The building material is light, simple, and easy to work with.  Forms have male/female interlocking surfaces that simply snap together like Lego.  Once assembled, concrete is poured into the form.  Because the foundation forms remain in place after the concrete is poured, they help insulate the home.

How to build Insulated Concrete Form foundation walls

As with traditional methods, building the foundation starts with casting a footing that is perfectly plumb and level.  The bottom row of forms are positioned along snap lines and an adhesive used to secure the base row in place.  Rows of ICFs are then stacked upward, side forms separated by furring strips (hinged, plastic web spacers) that snap into place.  To reinforce strength, rebar is laid across rows horizontally and dropped in vertically.  Once the structure is prepared, concrete mix is pumped in through a hose.  A vibrator is employed as concrete fills in order to remove air voids and ensure flow through any obstructions within the forms.  Once fully filled and allowed approximately one week of cure time, waterproofing is applied before backfilling.  The finished result is an air-tight foundation that is insulated inside and out.

COMPARISON:  Insulated Concrete Form Vs. Poured Concrete Foundations

(Courtesy of

ICF foundations are more energy efficient, less prone to moisture intrusion, less sensitive to cold temperatures than poured concrete foundations.

  • ICF foundations have an R-value of greater than 20.  Poured concrete foundations have *R-values of less than 3.
  • *R-Values — An insulating material’s resistance to conductive heat flow is measured or rated in terms of its thermal resistance or R-value — the higher the R-value, the greater the insulating effectiveness.
  • Because the forms protect the concrete of ICF foundations, they are less susceptible to cracking and leaking than poured concrete foundations.
  • ICF foundations can be constructed most times of the year because the process is not as sensitive to cold temperatures as pouring concrete.
  • ICF foundations have about double the compressive strength of conventionally poured concrete foundations. Therefore, there is less opportunity for moisture intrusion with ICF than poured concrete.
  • Poured concrete foundations are more prone to shifts in the ground and water pressure than ICF foundations.  So, poured concrete foundations are more at risk of cracking and leaking, which can lead to mold and mildew growth.

ICF and poured concrete foundations both strive to support a building and resist lateral forces and buckling.  However, a high-performing ICF foundation is more energy-efficient and resistant to cracking and moisture intrusion than poured concrete foundations.

How do costs compare?

ICF wall construction can increase the cost of your home’s foundation by approximately 30 to 40 percent as compared with the traditional method.  Note however, given the recent escalation in lumber prices, the price gap is closing.  Future energy savings is another factor to consider when comparing costs long term.

Canadian Suppliers

Fastform ICF                               

Nudura Insulated Concrete         

Logix ICF                                     

Nexcem Insulated Concrete Forms