What the Heck is an ICF?

While preparing for a potential power outage recently due to freezing rain, I couldn’t help but notice this radio as inspiration for writing my next blog post. You would likely think I am going to talk about emergency preparedness, but I am looking at the model number, particularly the first three letters, which as you can see are ICF.

Yes, this is a radio in a blog post that has nothing to do with them.

​In the world of home construction, ICF is an initialism for Insulated Concrete Forms. While it has only become common in the past 15 years it actually dates back to its invention right here in Canada in 1966. An ICF is composed of two main components: insulation, almost always in the form of expanded polystyrene (EPS) and concrete with steel reinforcement (rebar). They can be used in both foundations and walls, although the latter is less common. The insulated blocks are used to hold the concrete while it cures (just like the removable plywood used in regular concrete construction) and are permanently left in place to provide valuable wall insulation. ​

The first time I saw one in 2007, I thought it looked like someone enjoyed Lego a little too much!

I recently did an inspection where my client wanted to know what an ICF was and how far it went up the walls. While I typically see them just used as the home’s foundation, this particular home inspection showed that the entire wall structure right up to the rafters was constructed of ICF. So, is that a good thing? The cliché answer is that it depends. My professional answer is an absolute yes, but it definitely has drawbacks.

First, the Bad News
There are a number of disadvantages to ICF construction. Some of these include:

• ICF houses cost more to construct. Estimates are between a 6-10% increase in construction costs over a wood framed house, although with the recent increases in the price of lumber this gap has likely lowered and will continue to do so.
• ICF houses are more difficult to renovate. While I complain constantly about how the various home improvement shows make it look far easier than it is, ICF takes it to another level. It is more challenging to install new plumbing and electrical and it is almost impossible to add new windows, doors, etc. at a reasonable cost to an ICF home.
• All concrete releases large amounts of moisture when curing, which is why finishing a basement in a brand-new home is highly discouraged within the first year. ICF walls will introduce excess humidity to the entire house and extra dehumidification will be necessary, especially during the first summer.
• As an inspector, it is very difficult if not impossible to closely inspect ICF foundations. As they are buried behind insulation and a masonry veneer, any cracks or potential structural issues are not immediately apparent. In my experience ICF houses are usually well constructed so this isn’t a major concern, but I do like to be meticulous in my work.

Advantages of ICF
There are many benefits to an ICF home. While I only report and never make advice on buying decisions, I definitely get excited when I see ICF construction. Some upsides include:

• ICF walls are not only more energy efficient, but they are also great at blocking noise.
• ICF houses, in my experience are downright comfortable in the summer. None of the ICF houses I have inspected have permanent air conditioning installed, and that is because they tend to better resist heat movement, either in or out.
• ICF materials provide excellent indoor air quality, although like most modern homes they do require mechanical ventilation to remain healthy. The insulation is not toxic and do not contain Volatile Organic Compounds (VOCs).
• More rebar is used in ICF construction. Without getting into building science or engineering, concrete is very strong against compressive forces but weak against tension forces, which is why it needs to be reinforced.  ICF walls are generally very strong and highly resistant to wind and other forces of nature.

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​Overall, I draw parallels to my post on heat pumps. While there is a significant initial upfront cost, the savings in both money and energy over the long run make it all the more worthwhile. Unfortunately, the higher price tag can scare many developers and new homeowners off but to this home inspector, it is an investment well worth the initial expense.