Strange as it may seem, there are some people in this world who do not know what ICF means. Let me help change that. ICF is an acronym that stands for Insulated Concrete Forms. Basically these are stacking styrofoam panels with webs spreading them apart. When the blocks are stacked up according to design, they create a hollow wall with styrofoam on the inside and the outside. This has reinforcing rod placed in it, then is pumped full of concrete to create a solid, insulated, concrete wall.
ICF blocks do have a variety of webs with different sized spacings, creating different thicknesses of walls, depending on your construction needs. The webs are specially designed to accommodate horizontal reinforcing rod on each layer. In addition, the tops and bottoms of the panels have a locking system roughly comparable to Lego blocks. This why some figure that building with ICF blocks is like child’s play!
There are a number a ICF manufacturers, who all have the best product ( or so they say ). If building with ICF, it is advisable to do some research before proceeding. There are blocks that come pre-assembled, which is a time saver on site, but bulky to store and transport. Other manufacturers build blocks that come in flat panels and the web has to be clipped in on site. A few more options are available as well.
Most manufacturers make a variety of blocks, for specific purposes. They may be 90 degree corners, or angled for a bay window, or rounded, some even come with a brick ledge built in. With a wide range of choices, almost any type of construction is possible, from houses to commercial buildings.
When it comes to windows and doors, the contractor will build the appropriate sized ‘bucks’. These are basically wood framing members that are the correct sizes for the rough opening of the window or door. The ICF blocks are arranged around the bucks, and when the concrete is poured, the bucks become an integral part of the wall.
Building with ICF blocks is not a new concept, but it has taken a while for it to become an accepted method of construction.
So WHY would anyone build using ICF blocks ?
There are numerous reasons to do so, and I will list some of the more obvious ones.
Time Savings – The blocks are quick and easy to assemble, cutting them to size can be done with a utility knife or a handsaw. Once the footing is in, the words to remember are ‘square’ and ‘plumb’. It is important that your contractor has the proper scaffold/bracing to keep the wall straight and plumb. There are no forms to be set up, taken off, moved around and hauled in and out. It goes up quick and easy.
Insulation – When building a conventional concrete basement, it is normal especially in colder climates to frame up a wood stud wall on the inside and insulate tha wall as well as the pony wall above. This is not necessary with ICF. In some cases, the ICF blocks are used up to the trusses. When this is done, again there are insulation benefits. When there are insulation benefits, this usually translates into lower costs to heat or in some climates, to cool.
On a wood frame house it is quite common to have air transference through the wall. On an ICF home this does not happen. If fact, the home is so airtight that an air to air heat exchanger system is recommended to maintain a supply of fresh preheated air.
An added benefit from the insulation is that the insulating factor of the styrofoam enables the concrete to cure more slowly and the end result is concrete that is stronger.
Sound – A solid wall does not allow sound to transfer as much as a wood frame wall. The main area that sound will come in through are the windows and doors. So even though there may be noise from traffic etc, the inside of the house will remain undisturbed by outside noise.
Health – The ICF styrofoam is called Expanded Polystyrene. This process is done using steam, reducing chemical emissions. A wood frame house has a significant amount of chemical offgassing, which can have detrimental effects on health. Mold and Mildew are also less likely in an ICF home.
Insects – Until a new super insect is discovered, there doesn’t seem to be any insects that love to eat concrete. In fact, they don’t eat concrete, so the ICF construction does drastically reduce insect problems. The worst case scenario would be if some insects decided to nest in the styrofoam. It is much more likely that they will go in search of a more consumable house.
Cost – Although initially the cost may be a bit higher than wood frame construction, there is a payback from reduced heating and insulating costs. In order to realize these cost savings, one should live in the house for a minimum of 5 years. In addition, some insurance companies offer a discount when an ICF home is built in an area of hurricanes and tornadoes.
So, as one who has built and lived in an ICF home, I would definitely recommend it, but it may not be the preferred method of construction for everyone. Do your research, ask lots of questions, maybe even go to a build site and watch the process. Then make your decision. If you choose ICF, I’m sure you won’t regret it.