ICF architect

Insulated Concrete Forms (ICF) are becoming increasingly popular in the construction industry as a building system.  As an ICF Architect, many clients inquire about the advantages and disadvantages of ICF construction.

While ICF construction may increase the building budget 5-10%, there are also some obvious advantages utilizing ICF construction.  An ICF Architect can advise you of advantages and disadvantages of ICF construction at the architectural brief stage.

ICF Thermal Insulation.

An ICF Architect recognizes that the premier benefit of ICF is the higher R-value and thermal resistance of walls.  ICF construction has 100-150mm/4-6 inches of in-situ concrete sandwiched between 50-75mm/2-3 inches of foam.  Depending on the diurnal pattern, the ICF structure slows thermal movement and reduces heat loss and heat gain.  Compared to traditional housing construction, the improved energy efficiency can reduce heating and cooling costs between 20-50%.  Therefore, the payback period for the higher budget and initial capital cost is relatively short.  Traditional structural timber framing with fiberglass batt insulation has a calculated R-value between 13-15.  ICF wall construction nominally 4″ of concrete thickness achieves between R32 to R50.

Structural Integrity.

The reinforced concrete core contributes to the strength and stability of ICF construction to withstand larger dead and live loads.  This increased structural capacity provides resilience to extreme weather wind loads such as cyclones, tornado’s, hurricanes and earthquakes.  ICF construction minimizes building damage from earthquakes due to the walls capacity to withstand compressive and tensile loads.  The rapid gains in ICF construction popularity is primarily due to the structural integrity of the composite wall construction.

Sound Insulation of ICF

The tertiary benefit for an ICF Architect is the sound insulation as defined by its Sound Transmission Class (STC).  The higher the STC rating, the more resilient the wall construction is able to withstand noise ingress into living spaces.  The ability of a wall to block noise from the external environment to internal living spaces is the STC rating.  The STC rating requirement for building construction is defined by the National Construction Code and International Building Code.

Fire Resistance.

An ICF architect would also present ICF’s attribute to withstand fire to clients at the project’s architectural brief stage.  Material fire ratings are assessed in testing laboratories and rated/measured in hours.  ICF construction provides fire ratings between 3-4 hours which far exceeds fire ratings in traditional construction.  This aspect of ICF construction also impacts the payback period as it can reduce insurance premiums over the building’s lifecycle.

Impact Resistance.

ICF construction is able to withstand a projectile traveling at over 200mph with little more than a dent.  The military have tested ICF blocks for use in combat areas and have proven to resist numerous ballistic tests.

ICF in Passive Solar Design.

An important element in passive solar design is a building’s thermal mass.  ICF walls can act as thermal mass and regulate interior temperatures when correctly positioned in the architectural plan layout.  The thermal mass of the ICF wall construction can reduce temperature swings during the diurnal movement of the sun.

The choice of structural engineer is a critical decision that effects the profitability of an ICF project.  On one project, clients wanted to use an acquaintance who was an engineer.  The clients convinced were convinced would receive what’s colloquially now as; “…mates rates…”.  Although other competitive engineering fee proposals were received, the clients chose to proceed with their engineer.  Upon completion of the architectural and engineering contract documentation the project was bid to six general contractors.  When the range of bids came for the project was over budget; there was a need for redesign.  Although the client wanted to mothball the project; I sought intervention from our ICF engineer.

The lowest bid showed high costings in the concrete and steel specification sections. due to the client’s engineering specifications.  I recommended the client have a review of the engineering drawings by TAC’s ICF structural engineer.  Over thirty years of managing building bids, I‘ve consistently seen structural fees are a fraction of concrete and steel costs.  After a revision of the structural engineer’s drawings; the project was sent out for costings.  After the second bids, the cost of granowork labor, concrete supply, steel supply and steel fixing was reduced six figures.