- Home
Is ICF Used In New or Existing Projects?
ICFs are found mainly in new construction rather than retrofitting projects. They are easy to install and have several advantages, including strength, durability, and the ability to be well-sealed and well-insulated.
What is ICF?
Insulated concrete form (ICF) is a system of expanded polystyrene (EPS) rigid insulation blocks separated by plastic webbing. It is used as an integrated concrete form to pour a concrete wall instead of a traditional wood plank or plywood form. ICF blocks come in interlocking sections, so a wall system fits tightly together. Once the blocks are in place, concrete is poured, and finishes like drywall and siding are attached to fastener strips embedded in the insulation.
Several steps of the construction process are made quicker because the insulation and fastener strips are included with the ICF blocks. ICF walls are typically between 6" and 12" thick. Wall thickness is often impacted by the soil condition and the amount of support that the overlying parts of a building require.
Fun fact: Werner Gregori, a Canadian contractor, filed the first patent for an insulated foam concrete form in 1966.
It is also important to remember that the amount of time required to compile all of the necessary permits for an ICF home will likely take longer than for a conventional home. Since this is not the standard in the residential construction industry, the permitting process can be a bit more arduous. A licensed builder will likely be familiar with this process to make it a smoother (and hopefully quicker) experience. And, for those DIYers out there, ICF homes are not something that we would recommend attempting yourself if you are not a licensed professional.
How Much Does ICF Save Over Time?
The savings and payback of an ICF home are primarily dependent on what you are comparing to and how well the home is built. If you have a home with an extremely tight building envelope, you will likely experience more considerable savings. While you will probably pay 5% - 10% more upfront for an ICF home, your energy bills will be lower each month than if you were to build a wood-frame home built to typical standards. Industry leaders share that if you compare the initial cost of an ICF home to the utility savings over time, it costs the same as a wood-frame home. But, again, this is dependent on a variety of factors.
What is the Maximum R-Value of an ICF Wall?
ICF construction has two advantages in terms of the energy performance of the building. First, it seals very well, preventing air leakage through the walls. Second, it has two continuous insulation layers, one inside and one outside, with no thermal bridges. This tight building envelope dramatically reduces heat loss.
Shop Sales On Rise
Stiebel Eltron CON 300-2 Premium Wall-Mounted Convection Heater - 202030
Stiebel Eltron
In Stock
Stiebel Eltron Accelera 300 E Heat Pump Water Heater
Stiebel Eltron
In Stock
Drolet HT-3000 Wood Burning Stove DB07300
Drolet
In Stock
Victory Range Hood Sunset 600 CFM White Flush Ceiling Mount Dimmable LED Range Hood
Victory Range Hoods
In Stock
Stiebel Eltron DHC-E 8/10-2 Plus Point-of-Use Electric Tankless Water Heater - 202145
Stiebel Eltron
In Stock
Stiebel Eltron CON 150-1 Premium Wall-Mounted Convection Heater - 202026
Stiebel Eltron
In Stock
Stiebel Eltron Accelera 220 E Heat Pump Water Heater
Stiebel Eltron
In Stock
Victory Range Hood Sunset 600 CFM Flush Ceiling Mount Dimmable LED Range Hood
Victory Range Hoods
In Stock
Drolet Bistro Wood Burning Cookstove DB04815
Drolet
In Stock
Stiebel Eltron CON 200-2 Premium Wall-Mounted Convection Heater - 202029
Stiebel Eltron
Out of Stock
When building a high-performance house, like a Passive House, a typical off-the-shelf ICF system is often not thick enough. It may also struggle to meet the insulation standards in a cold climate like Canada or the northern USA. Fortunately, some ICF manufacturers, like Nudura, have created products with an R-value of up to R-48 to address colder climates.
You can add more insulation to the outside, especially for a foundation, as Phil Dennis did in his Gaspereau Passive House with four extra insulation inches.
On the above-grade walls, adding extra insulation to the inside can work better than the outside. And to make it easier, some companies now offer ICF options with thicker insulation. One example is BuildBlock Building Systems, which sells 1" or 2" inserts that attach to the interior of their ICF wall, adding an insulation value of about R-4.2 per inch.
Because of how durable ICF homes are, it does make remodeling difficult. If you foresee wanting to remodel your home in the future entirely, you might want to consider a more flexible building material.
Dave Phelps of ICF Homes of Virginia has witnessed similar results in building ICF homes. "For every three concrete houses we build, it uses the same amount of energy as one wooden house. So if we want to look at energy efficiency for homes, 3 to 1 is an incredible ratio that we can't meet with building houses with wood."
Overall, ICF homes increase your home's comfort, reduce your monthly energy bills, and, most importantly, reduce your environmental footprint. ICF homes are considered high-performing due to their higher thermal resistance and thermal mass, along with stricter construction standards than are typically required for conventional wood-framed homes.
If you build a high-performance home insulated well above code to standards like the Passive House standard, your building will have a much lower energy footprint. That means lower energy bills and even greater sustainability.
Additional Resources
If you choose ICF construction, ask for concrete with fly ash content to use recycled materials. If you decide to go with wood-framed construction, look for FSC certified wood sourced as locally as possible. See our insulation guide to learn more about EPS, blown cellulose, and other kinds of insulation.
Maria Saxton
Located in Roanoke, Virginia, Maria Saxton holds a Ph.D. in Environmental Design and Planning from Virginia Tech. She works as an Environmental Planner and Housing Researcher for a local firm specializing in Community Planning, Architecture, Landscape Architecture, and Historic Preservation. Her dissertation explored the environmental impacts of small-scale homes. She serves as a volunteer board member for the Tiny Home Industry Association.
