Insulated Concrete Forms: Pros and Cons

Are you thinking about using insulated concrete forms (ICF) to build your new home? We’ll cover what ICF is, how it works, and the pros and cons of ICF construction. Here’s what you need to know about this energy-efficient building material.

What Are Insulated Concrete Forms (ICF)?

Insulated Concrete Forms (ICF) is a type of wall building material used in home building. It’s an alternative to traditional wood-frame housing.  

Usually, concrete is poured into wooden forms that are removed once the concrete is dry. Insulated concrete forms (ICFs) are permanent forms that help insulate the home once the concrete is dry. The forms come in stackable, interlinking blocks that are stacked and linked to form walls, ceilings, or foundations that are filled with concrete.

Photo by LogixICF

What Is ICF Made From?

There are two main parts to an ICF: expanded polystyrene for the insulation and webs or cross ties that are usually made of polypropylene plastic.

Here are some specs and benefits of insulated concrete forms:

  • Type II, closed-cell foam
  • High R-value per inch (R4) – the higher the R-value, the greater the insulation performance
  • Moisture-resistant and non-absorbent
  • Resistant to rot and mold
  • Recyclable
  • Contains a flame-retardant
  • Non-toxic smoke

ICF Benefits

There are a wide variety of benefits to using ICF compared to wood-frame building.

Faster Build Time

Building with ICF may cut 2-3 months off the construction time of your home. That’s because ICF saves steps in both the exterior and interior construction.

Credit: ICFMA

ICF Cost

While it used to be considered expensive to build with ICF, lumber framing labor has finally all but caught up with the cost of ICF construction, making it a comparable and affordable option for homeowners.

ICF forms cost an average of $3.50 to $4.00 per square foot. Once you factor in additional costs like concrete, rebar, hardware, bucks, labor, insurance, and more, the average total cost using ICF forms is around $14-$20 per square foot of ICF wall area.

Fire Retardant

ICF will not combust. Even if a fire ravages the inside of your home, the walls stay standing. That also helps prevent the spread of fire from your home to another, stopping the fire when it reaches your exterior walls.

California Wildfires

This home built with Insulated Concrete Forms narrowly escaped destruction in 2018’s California’s wildfires, which burned 18,804 structures and took 85 lives.

Other homes in the neighborhood were completely consumed by flames, but this one, built with ICF, survived.

Energy Efficiency

With insulation on both sides of the concrete, your wall temperatures won’t change throughout the day, achieving a consistent R-23. Whereas wood frame walls do not have consistency and max out at R-19, but typically range from R-9 to R-15. That means less energy is required to heat and cool your home – a savings of 20% to 50%!

An independent study conducted by CLEB Lab concluded that an ICF wall provided 58% greater R-value and 43% energy-savings compared to the wood-frame wall.

ICF walls are also less drafty than wood-frame walls. In fact, it takes almost three days for radiation, convection, or thermal heat transfer to make it through the exterior wall.

Quieter

Walls made with Insulated Concrete Forms insulate sound better than traditional walls, so your home will be quieter. Standard wood framed walls have a Sound Transmission Class (STC) rating of 33-38, whereas an ICF home has a consistent STC rating of 54, which means shouting outside the walls is not heard.

“1,000-Year Homes”

Homes made with ICF are sometimes called “1,000-year homes” because there’s little to prevent them from surviving intact for hundreds of years. The walls are strong enough to withstand up to 250 mph hurricane winds and tornadoes, earthquakes, and are fire-resistant for up to 4 hours. They’re unlikely to suffer from slow degradation the same way wood-frame walls do, so they stand the test of time.

Here are a few examples of how ICF homes weathered the storm…

ICF Home Survives Hurricane Dorian

One of the worst natural disasters to hit the Bahamas, even Hurricane Dorian could not take down this ICF home on Grand Abaco Island after 36 hours of punishing hurricane winds.

Hurricane Michael Survivor

This ICF home in the Florida Panhandle was virtually the last home standing after 150+ mph hurricane winds hit it. Hurricane Michael completely destroyed 54% of homes in the area and another 23% were severely damaged. This home was built only a few hundred feet from the water’s edge and weathered the ferocious wind and storm surge with ease.

Storm Surge and Debris

This Cayman Islands ICF home survived the storm surge from Hurricane Ivan in 2004 despite being battered by cars, rocks, and other debris.

The storm surge forces and battering waves of Super-storm Sandy in 2012 were too much for the homes in Union Beach, New Jersey, but the family who built this ICF rode out the hurricane in their two story home while waves broke on the house itself.

Nontoxic and Healthier Air Quality

ICF contains no HCFC, formaldehyde, fiberglass, or asbestos and doesn’t suffer from off-gassing. And, no harmful CFCs (chlorofluorocarbons) are used in their manufacture.

ICF walls provide a tight, low air filtration wrap to your home. This is the first step in controlling the indoor air environment.

  • ICF walls reduce air infiltration by 75%.
  • Eliminate dust mites.
  • Prevent dangerous and costly mold.
  • The effects of hay fever, asthma, and other airborne allergies can be greatly alleviated as a direct result of the reduced leakage of outside air, which brings dust, pollen, and other pollutants.
  • Indoor air pollution is a great health concern today. ICF walls are non-toxic. The measurement of air contents of actual ICF houses shows an almost complete absence of any emissions.

Net Zero

When paired with solar tiles, a home built with insulating concrete forms becomes net zero. The World Green Building Council (WorldGBC) defines a net-zero carbon building as one “that is highly energy-efficient and fully powered from on-site and/or off-site renewable energy sources.”

Unlike some other countries (like Canada), the United States doesn’t require new homes to be net-zero. However, WorldGBC is dedicated to supporting market transformation toward 100% net zero carbon buildings by 2050 to achieve Paris Agreement levels of global emission reductions.

Credit: WorldGBC

Year-Round Building

Unlike using traditional forms, concrete can be poured into an insulated concrete form any time of year, regardless of how hot or cold it is. That means your home can be built at any time of year.

Lower Homeowner’s Insurance Premiums

Since walls made with ICF are so resistant to wind, fire, and flooding, your homeowner’s insurance premium will be lower than it would be with traditional wood-frame walls.

ICF Disadvantages

While ICF is a wonderful building material, it does have a couple disadvantages. These include:

  • Difficult remodeling. Adding doors or windows in the future will be tricky since you’ll be cutting into concrete. You need to plan ahead when designing your floor plan.
  • Floor space. Walls made with ICF are typically thicker than traditional walls, which means you’ll have less usable square-footage inside your home, but this is an insignificant difference.

Frequently Asked Questions

Here are answers to some of the most frequently asked questions about insulating concrete forms.

How Do Insulated Concrete Forms Work?

Insulated concrete forms are like hollow Lego blocks. Exterior walls are built using the forms, then filled with concrete. The forms stay in place to act as insulation. ICF blocks are usually 48 inches long and 16 inches high, but they come in varying shapes and sizes to accommodate corners and other needs.

What Do ICF Forms Cost?

ICF forms cost an average of $3.50 to $4.00 per square foot. Once you factor in additional costs like concrete, rebar, hardware, bucks, labor, insurance, and more, the average total cost using ICF forms is around $14-$20 per square foot of ICF wall area.

How long will an ICF house last?

Hundreds of years. ICF homes’ walls and EPS insulation lasts for centuries and doesn’t break down, collapse, decay, or fail when protected behind wall finishes.

Who Makes the Best ICF?

There is no precise way to determine who makes the best ICF. A few tips for choosing the best insulated concrete form blocks for your project include:

  • Does the manufacturer offer excellent support?
  • Are the blocks code approved?
  • How high are the R-values (a measure of heat transfer)?
  • Are the ICFs easy to assemble?

We Offer Insulated Concrete Forms

To learn more about how insulated concrete forms (ICF) might be the best solution for your new home, contact us today. Click here or call 512.402.9222.

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