Insulated Concrete Forms (ICF)
Insulated Concrete Forms (ICF) are a construction material system used to build walls. Originally the name was for a rigid styrofoam system that was used to form concrete walls. The styrofoam material would stay in place after the walls were poured adding additional insulation. Over the last couple of decades, other products came to market that were different than this original scheme. These include AAC blocks (autoclaved aerated concrete) which have air bubbles imbedded in what look like solid concrete blocks. Other products look like traditional cinder blocks but are a mixture of concrete and styrofoam (or some other insulating material).
The styrofoam system, shown in the picture below, would typically be handled by a concrete trade as it is similar to forming up and pouring a concrete wall.
The other systems are similar to traditional cinder blocks (CMUs) to install. So this work could be done by a concrete trade or a mason. The pics below show an AAC product.
The are specialty installation procedures for each type of product and trades unfamiliar with them will need to get training from the manufacturer (which most of them readily offer).
For the sake of comparing ICF with traditional stick frame construction, I’m going to assume all of the different types of ICF products are roughly equivalent in cost and benefits. If you drill down and look at each product individually, there are unique aspects to each, and the cost of the materials and installation costs will vary.
Primary benefits of ICF over stick frame:
Strength - It’s essentially a concrete wall. So it certainly wins the strength test…
Energy Efficiency - It has both thermal mass and excellent insulating properties. Compared with stick frame and spray foam it is typically a superior wall system.
Pest Proof - The systems are generally termite-proof. And other small bugs and animals would not be able to penetrate (or chew) through them like they would an unmaintained wood-framed structure.
Fireproof - The systems are fireproof. However, most exterior building cladding are as well (Hardie siding, stone, stucco…). Also, when wildfires are involved, most homes are more susceptible to fire penetration at the roof and eaves. So this benefit is pretty equal to that of wood construction.
Sound Attenuation - The wall systems are superior to wood frame and spray foam. However, the windows and doors will need to be a high enough quality to realize this benefit.
Cost Comparison - In general, from the numerous analyses I’ve run over the years, I’ve found that ICF systems add about 10-15% to the total cost of the project. This takes into consideration the savings in not having to insulate the walls, the cost savings of a 1 or 2-coat stucco application vs. a 3-coat application on wood sheathing, the additional cost of the MEP trades (and other trades) in dealing with the wall system, etc.
When homeowners ask me about my recommendation on IFC, I tell them the following: It’s a great system with many advantages over traditional stick-frame wall systems. If you're hoping to have a financial return on the additional investment, this is unlikely to ever happen. So if you want to go with IFC, great, but a financial return should not be one of your motivating factors.