What is an ICF Wall?

Home construction technology and advanced materials have come a long way in recent years. This is where ICF walls come in. ICF stands for Insulated Concrete Forms. But what exactly does that mean? How is it better than older technologies and why would I want it used on my new home?

Concrete walls traditionally have been constructed of either concrete blocks or poured concrete. Most homes with full basements have poured concrete walls. They are built using wood forms. It takes a lot of time and hard work to construct the wood forms and brace them to hold the heavy concrete. Then once the concrete has been poured, the forms must be left in place for several days to allow the concrete to set. After which time the forms must be dismantled and removed. This process is time consuming and very labor intensive.

After the concrete forms are removed, the walls must be sealed and then insulated. This adds more time to the home’s construction.  When it comes to building a home, time is money. More people working means more labor costs. In the end you will have a poured concrete wall that is sealed and insulated with foam board.

How are ICF Walls Different?

Insulated Concrete Walls are built using specially designed foam blocks. They lock together like LEGO’s. They have an open interior with plastic supports. These supports are designed to accommodate reinforcing steel (rebar). The foam blocks are light weight, easy to handle, and very easy to customize in the field. They can be used to build any size, shape, and height of wall needed.

Being light weight and easy to use, the ICF blocks speed up production. Usually a full set of ICF walls for a basement can be constructed in less than a day. Concrete is then poured into the hollow space between the blocks. This step is the same as using wood forms.

However, after the concrete has been poured there are no forms to remove. What you end up with is a steel re-enforced sandwich wall of foam and concrete. There is no need to add any insulation to the interior or exterior of the wall. It is not unusual for a ICF walled basement foundation to be constructed, and the concrete poured, all in the same day.

Why is ICF better?

Beyond saving any where between $500 & $2000 during construction, there are other benefits to an ICF wall. There is the increased energy efficiency. A home built with ICF walls need an estimated 40% less energy to heat, and up to 30% less energy to cool. These savings increase with larger homes.

(This is a great article on home construction using ICF.)

It comes down to how “air tight” a house is. You can cut air leakage by using ICF as apposed to wood construction. This tighter envelope is key to keeping your house efficient.

Another thing to consider is thermal mass. Concrete has heat-absorbing properties, which is called thermal mass. This will smooth out large swings in temperatures. ICF walls will add back cooling or heating to a house which can be as much as 5% of the energy needed to keep your home comfortable.

If you are considering building a concrete block home, you should look into ICF walls. And of you are thinking about adding a full basement, ICF walls should be kept in mind. They save money, speed construction, and are very energy efficient.