Page 8 - GB Building Science Ebook 2019

01 SIX CHANGES

A STRUCTURAL SHIFT

LONG WITH LACK of workers, back in 1998 that an ICF home (prior to the
other forces have made alterna- current labor shortage), would cost about 3
tives to stick-built homes more SHARE OF percent more than stick framing with 2x6
attractive. For example, accord- lumber.
Aing to the NAHB, President BUILDERS Other, more recent estimates put the cost
Trump’s tariffs on Canadian lumber alone difference lower. Concretebuilding.org suggests
have added another $9000 to the cost of each that “Building walls of ICFs adds $1.00-$4.00
new home. It’s not just lumber. The tariffs REPORTING per square foot over stick framing. But since
contributed to material shortages in many ICF buildings are more energy-efficient, the
categories (see list at right). SHORTAGES heating and cooling equipment can be smaller
As builders ponder shortages and more than in a frame structure. This can cut the
demanding codes, they’re diving into the cost of the final building by an estimated $.75
numbers to compare overall costs for different % of Respondents who per square foot. So the net extra cost is about
structural systems. Many studies have been Purchase the Material $.25-$3.25.”
conducted over the years on this topic. We That cost gap for materials has closed as
went through the latest literature to offer some Framing Lumber 31% lumber prices have risen. But the real value
general guidelines on what you can expect in ICFs, according to advocates, may go to
with each system. Trusses 24% the homeowner, not directly to the builder.
For example, concretenetwork.com suggests
STICK FRAMING PLUS Steel (light for 20% that “in reality, you may save money by
The process of stick framing has improved framing) building with concrete when you factor in
incrementally, but not fundamentally, over the OSB 20% life-cycle costs, utility and insurance savings,
past two decades. Houses are generally better maintenance requirements and overall health
built and stronger, thanks to new types of fas- Plywood 19% of the occupants.”
teners, integrated clips and engineered wood ICFs also appeal to the DIY market, because
trusses, rafters and other components. More Gypsum wall board 18% the lightweight forms are easy to handle and
new homes are built with high performance assemble. However, the blocks are only part
2x6 wall layouts, and some use parallel con- Cabinets 17% of the system. The hidden costs in ICF homes
struction to achieve higher R-values. happen in the detailing. They require many
But stick-framed construction remains a Steel beams 17% specialized components, for example, to
complex and labor intensive process. When finish door and window openings, and pour
labor is consistent and available, dry-in for a Millwork 16% succesfully.
2500 sq. ft. home requires about six weeks. Here’s what one ICF builder noted from his
Dry-in would include windows, doors and Clay brick 16% experience as the “extras” associated with an
roofing, with labor accounting for about 46 ICF project:
percent of construction costs. But as noted Windows and doors 15% ■ ■ Rented or site-built bracing.
above, labor problems abound, so that time ■ ■ Foam gun and a lot of cans of foam to
frame can easily extend out to eight or nine Roofing materials 13% fill voids.
weeks. ■ ■ Material for door and window framing.
That extra time costs. It means extra rental Ready-mix concrete 13% ■ ■ Clips to keep ICFs from floating.
fees, extra spent on salaries for idle employees. SOURCE: NAHB 2018 ■ ■ Wire ties in the corners.
The list of undermining costs go on. This is Insulation materials 12% ■ ■ Sill material at the top of the wall, and
when many builders look for other systems. Structural insecurity? Note that fasteners such as J-bolts to secure it.
nearly one-fourth of builders have ■ ■ Ledger system for the floor(s) and the
ICFS: EXPERIENCE PAYS experienced shortages in framing related hardware.
One common alternative to stick framing is materials recently. Different ICF products, of course, have their
Insulated Concrete Forms. HUD estimated own solutions for some of these detailing

8 BUILDING SCIENCE SPECIAL REPORT: SIX WAYS CONSTRUCTION IS CHANGING