Recently I had the opportunity to visit a project being constructed out of insulated concrete forms (ICFs), and I was impressed with the simplicity and versatility of the system.
As you can see, they ship flat then open into blocks that snap together like Legos with ties that are prepped for rebar on the horizontal.
I assumed that using ICFs would constrain you to very “blockish,” non-flexible design, but I was quite surprised to learn that columns and steel beams can actually be incorporated to create higher ceilings, mezzanines, and balconies.
The project I visited is a hotel in a suburban environment with a relatively basic design. The exterior walls, stairwells, shafts, and walls between units were built using ICF with a floor system done in precast concrete plank.
Some Pros of ICF: Fire safety, mold resistance, sound and fire rating between units, longer lifespan than wood, faster than traditional concrete systems, R-Value (x%), disaster “resistant.”
Some Cons of ICF: More exspensive than wood, loss of square footage due to thickness of wall, and MEP Rough-in.
You may be wondering, like I am, about how ICFs compare to traditional concrete systems or wood in terms of cost and environmental impact. There seems to be a lack of unbiased information about the system, so finding accurate data is difficult, making it impossible for me to say for sure at this point.
Where I think the system starts to make a lot of sense is in residential conditions. You need to have a fire-rated wall between units, and you are required to have a minimum STC of 50. Not only is that built into the system well above code, but you’re also able to build critical walls early on without concern for water intrusion.
All that being said, this product has not yet gained much traction in the Northeast, but it is certainly worth a look in certain conditions. The calculations need to be done to see if the benefits outweigh the cost premium and loss of square footage.
Have you used ICF, or do you have solid numbers around cost comparison to wood? I’d love to hear about that as well as any questions or feedback you might have. I can be reached at joe@massconstruction.org
