Affordability of Building with BuildBlock ICFs

The Quality of Concrete Costs Little More

The many benefits of a concrete house built with insulating concrete forms (ICFs) are available for only slightly more than the cost of ordinary wood frame. ICFs are simple to assemble and they consolidate several construction steps into one. The walls can be economical despite the use of high-quality materials.

The cost of ICF Construction by component.

The cost of ICF Construction by component.

 

What is the “true” cost of an ICF home?

On average, new houses built by experienced contractors cost about 4-7% more than conventional 2×4 wood frame houses of the same design. But there are cost savings in other areas that will help to offset some of these first costs as well as provide the homeowner with significant improvements in day to day operational expenses and environmental impacts.

Since ICF homes are more energy-efficient, mechanical equipment can be smaller than in a frame home. This can typically result in at least 1% in up-front savings. So the net extra cost will be about 3 to 6% of the sale price of the home 1.

Higher quality exterior walls and smaller mechanical systems means less monthly cost for the homeowner with savings of at least 25% or more depending on the climate2. Downsized HVAC also results in reduced greenhouse gas emissions over the life of the structure compared to less efficient wood-frame construction 3.

The more experienced your ICF installer, the lower the cost of using ICFs becomes.

The more experienced your ICF installer, the lower the cost of using ICFs becomes.

 

What is an “experienced contractor”?

As with any innovative new construction product, the more a crew works with ICFs the more efficient assembling them becomes. ICF wall-building crews report that their costs drop sharply until they have built 4 or 5 houses. After that they continue to realize savings, but at a slower rate.

Mechanical contractors also need experience to size equipment correctly. If not experienced with homes as energy-efficient as an ICF house, they will tend to install equipment sized for a wood frame residence. Systems can be larger than necessary, do not run efficiently and the buyer loses potential initial day-to-day cost savings. In addition, excess moisture can build up in the house, causing unsightly and unhealthy problems. Helpful computer software is available for correctly sizing heating and air conditioning systems in concrete homes (see publication reference below).

Will homeowners save money living in an ICF home?

Because ICF walls feature thicker unbroken layers of insulation and the mass of concrete, they provide much better energy performance than conventional wood frame construction. Computer simulations comparing concrete homes to wood frame construction have shown the combined effects of higher R-values, low air infiltration and the impact of concrete’s thermal mass all combine to enable concrete walls to provide significant operating cost savings. Savings will vary by climate with the inherent thermal mass benefits having more impact in warmer locations and the added insulation being more critical in colder areas.

How can living in an ICF home reduce greenhouse gases?

Life cycle studies show most of the environmental load of a typical home is from the household use of natural gas and electricity during the life of the house3. Enclosing a home with more efficient ICFs means smaller mechanical equipment and lower fossil fuel consumption during the operating life of the house. This means the concrete house will generate less greenhouse gases than a comparable wood frame residence.

Why should I pay more?

Each year, the number of new home buyers who choose to have their houses built with concrete and ICFs continues to increase. Saving on the cost of fossil fuel consumption, and reducing emissions is a huge plus. But they also cite these additional advantages:

Comfort

ICF houses are far less drafty than frame, have far fewer “cold spots”, and maintain a noticeably more even temperature.

Quiet

Only about one-sixth as much noise travels through an ICF wall. Occupants are pleasantly surprised by the reduction in noise that enters from outside.

Strength

Owners of ICF houses feel less flex in their walls and floors. They notice virtually no vibration when they slam a door. Engineering calculations show the walls are much stronger than frame walls in many ways. Field data show they survive many types of natural disaster better.

Energy Efficiency

ICF walls cut an estimated 30-40% off the energy used to heat and cool a house.

What’s the bottom line?

When planning a new house, you can estimate that building the walls of concrete with ICFs and experienced crews will add about 3 to 6% to the overall cost of the home. The high performance of the ICFs will provide the concrete homeowner with significant reductions in energy consumption and emissions while providing a stronger, quieter and more comfortable home.

1. “RSMeans Residential Cost Data,” Reed Construction Data, Inc.
2. “Energy Use of Single-Family Houses With Various Exterior Walls,” by CTL Group for Portland Cement Association, 2001, PCA CD026.
3. “Comparison of the Life Cycle Assessments of an Insulating Concrete Form House and a Wood Frame House,” by CTL Group for Portland Cement Association, 2008,Serial No. 3041.

Source: Portland Cement Association Technology Brief 5

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