If you’ve ever tried to nail down a hard answer on this subject, you’re probably already familiar with the broad range of estimates out there.
To make your search a little easier, we’ve taken a look at the major reports on Insulated Concrete Forms cost throughout the USA and Canada and boiled them down to the basics.
The NAHB Research Center conducted a study to compare the cost and performance of Insulating Concrete Form (ICF) walls to conventional wood-frame exterior walls.
Three homes were built and monitored. One home has an ICF plank system, one has an ICF block system, and one is of conventional 2×4 lumber construction. The homes have identical floor plans. They are located side-by-side on the same street in Chestertown, Maryland.
Findings indicate that the labor cost for the ICFs was slight to moderately higher than for the wood framing. Total installed costs, however, averaged over $3000 more for the 1098 square foot single story ICF homes, or roughly $2.73 per square foot of floor area more than the wood-frame home.
This amounts to about 6% to 7% of the builder’s cost to construct the homes or 3% to 3.5% of the builder’s sales price. The increased cost of ICF homes is primarily due to the higher cost of materials relative to wood framing.
One thing that makes cost comparisons difficult is the fact that ICF blocks costs are usually measured in square feet of wall area while wood frame costs are measured in square feet of floor area.
Depending on the study, you might see Insulated Concrete Forms converted to relate to floor area, so it’s a good idea to keep track of what’s being measured to avoid any confusion.
Another thing to bear in mind is that different studies use different costs. Some give what the general contractor paid (referred to as builder’s costs or total house cost), while others give what the contractor charges to install ICF blocks (referred to as sales price).
Let’s take a look at some numbers:
A Portland Cement Association technology brief drawing from work done by VanderWerf, Feige, Chammas, and Lemay (Insulating Concrete Forms for Residential Design and Construction, 1997) concluded that insulated concrete forms cost builders about 5%-10% per square foot of floor area more than wood-frame houses of the same design.
At the time of the study, typical US homes cost the builder about $80-$120 per square foot of floor area, so using ICFs added about a $1.00-5.00 premium to this figure.
This held only for homes built by experienced contractors (who’ve built at least 4 to 5 houses).
Along similar lines, the NAHB Research Center’s Demonstration Homes Project also evaluated the use of ICFs in residential construction in 1997.
They experienced up to an 8% increase in total house cost, adding about 1-5% to the final price for the buyers. The NAHB’s Tool-Base report found that ICF Blocks increased builder’s cost by $0.75-4.00 per square foot of floor area compared to wood frame construction.
The Bottom Line:
So, where do all those studies leave us? The bottom line is this: ICF built homes cost slightly more than wood-frame homes. But by how much? It depends. There are so many potential influences on the price that it’s tough to nail down a reliable estimate.
Here’s why: concrete, lumber and foam prices, ICF form prices, lumber prices, exterior finishes, design features, crew experience, labor markets, and engineering all influence the cost of the intended project.
Results from the NAHB Research Center’s Demonstration Homes Project showed that total costs for construction of ICF foundation walls could be less than that for poured walls.
Insulated concrete forms cost:
One ICF system had total costs of $1.25 per square foot of house floor area compared to $1.27 per square foot of house floor area for the block wall based on the construction of a short (~ two-foot) “stem wall.”
An added cost of $2.50 per square foot of floor area seems to be in the middle of most of these ranges. But take that figure lightly; construction with ICFs can increase builder’s costs much less or more. It’s easy to see why there’s been so much debate on this issue.
All this being said, ICFs do have significant cost savings opportunities. Because ICF construction is more energy-efficient, HVAC systems can be downsized, and those savings offset part of the cost difference.
Using Stucco as your exterior finish will also reduce some of the cost since seeing that the base required for stucco installation is already set up.
Most builders report fewer customer service calls on their ICF homes
ICF homeowners enjoy lower utility bills, better soundproofing, and durability. Some have estimated that the monthly savings provide a real payback on the initial investment. And then you have the benefits of a stronger, quieter, more comfortable home.
The cost of ICF vs. more traditional methods of construction is typically more for the actual construction, but the cost of ownership of an ICF structure is significantly less than the more conventional methods. In nearly every documented case of the expense of an ICF structure, the return on investment (ROI) for the extra construction cost is within five years, with many showing less than three years.
Depending on how costs are viewed, ICF home may cost a little more or significantly less to build and operate.