California’s newly adopted green building code will have a direct impact on home building in the state, affecting energy details, plumbing, ventilation, and management of the construction sequence. But for home builders, figuring out just what the code requires could be complicated.

How complicated? Here’s one indication: When the state’s Building Standards Commission posted a draft of the new code on its Web site, they color-coded the PDF document in seven colors: black, green, yellow, violet, blue, orange, and brown.

That’s because the new green standard is a combined code that modifies the regulations administered by five different state agencies. The rainbow-like online presentation is meant to help citizens sort out which parts of the code belong to which agency (or agencies) and which sectors of the construction industry the language affects.

(“What’s interesting is that they can only do that online,” muses Justin Dunning, program coordinator for California Green Builder (CGB), a voluntary certification program founded by the state builders group. “They don’t print the hard copies of the code in color—they print them in black and white.”)

As Dunning notes, only part of the new code is mandatory. Other parts are scheduled to switch from mandatory to voluntary in future years, while additional provisions will stay voluntary indefinitely, as the state considers whether to make them mandatory. In any case, only part of the code—the sections adopted by the state department of Housing and Community Development—will apply to home builders. As it happens, however, all those residential parts are mandatory—although they won’t all take effect at once, or even at the same time.

So how do builders locate the sections that apply to them? “The orange wording is the part that is specific to housing. And the best way I have found to read the code is to look for the checklists at the back. The HCD checklist [adopted by the state Department of Housing and Community Development] is basically the residential component,” Dunning says.

Here are a few of the big changes builders will have to make.

Water Conservation. The new code aims to cut indoor water consumption (which does not include landscape irrigation) by 20 percent. “They’re doing that through the fixtures,” says Dunning. “Basically, if you take all the fixtures and reduce the flow rate by 20 percent, that reduces the inside water use by 20 percent … For a three-bedroom house, that is going to save about 10,000 gallons of water per year.” This adds up to less than the 20,000-gallon reduction over existing code required in the California Green Builder program, Dunning notes, but the CGB program includes outdoor water use. (CGB builders achieve their outdoor savings by reducing the area devoted to lawns or water-loving plants, emphasizing naturally drought-tolerant plantings, and installing high-tech irrigation controls that respond to natural moisture conditions.)

Energy Conservation. As far as homes are concerned, the new green code amounts to adopting the next version of the California Building Energy Efficiency Standards, the state’s energy code, which updates in July 2009. “Depending on where you are in the state, that will represent a 15 percent to 20 percent increase in stringency over the old code,” says Dunning. This is mostly the result of a change in window heat transmission values, or “U values” required. (The default window U-value will drop from .56 to .40.).

Waste Management. Under the new code, builders will have to ensure that at least 50 percent of the scrap and waste material generated on site is diverted from landfills and recycled or re-used.

Indoor Air Quality. The new code requires exhaust ventilation fans for every bathroom and high-efficiency filters on all air-duct systems. In addition, it lowers the allowable volatile organic compound (VOC) content for interior finishes, sealants, and carpet, as well as the formaldehyde emissions from composite products such as particleboard.

Construction Moisture Control. To keep mold and mildew at bay, the new rule requires vapor barriers under foundation slabs, and it requires builders to ensure that framing lumber is drier than 18 percent moisture content before installing drywall.

Air-Sealing Details. Joints and openings that might allow uncontrolled airflow between building interiors and the outdoors or attic, such as window edges, duct registers, or penetrations for plumbing, wiring, and gas piping, must be effectively sealed against air movement.

Site Design. All projects—even on small scattered sites of less than one acre—must implement measures to control erosion and manage stormwater runoff.

Homeowner Education. A maintenance and operation manual must be provided as guidance for building occupants.

How much will this cost builders—and home buyers? Experience gleaned from voluntary programs may be helpful.

 “For a builder who is building to today’s code—not the new green code, but existing baseline code—to get up to what the California Green Building program requires, costs on average about $2,700 per house. More than half of that is the energy efficiency portion,” says Dunning. The most costly change in the new code for many builders, he says, will probably be the low-flow toilets: “You’re looking at about a $250 premium to go from 1.6 gallon-per-flush to 1.2 gallon-per-flush.” Tighter VOC requirements will involve little cost, according to Dunning. (The new lower standards are already in effect in Southern California, where smog problems have led to strict controls). Complying with moisture control measures is largely a matter of keeping lumber covered during construction, although during the state’s brief winter rains, the new rules may cause some schedule delays. As for waste management, says Dunning, most waste haulers in the state already provide recycling or salvage for 75 percent of the waste stream or better, exceeding the 50 percent code minimum.

In the end, says Dunning, the management challenge may be the industry’s biggest hurdle: “The hardest part may just be for builders to make sure that all this stuff is getting done correctly on site.”

But the increased attention to detail may also be the source of the greatest long-term benefit, he says. “The more that the curtain is pulled back and builders can see that hey, this stuff really isn’t that hard to do — then maybe you start getting them to ask, ‘Well, what else can I do that is easy, that might give me a marketing edge?’” Dunning says. “I think the raising of the awareness within the home building community is probably the biggest impact this green building code is going to have.”

Ted Cushman is a contributing editor to BUILDER magazine.

Learn more about markets featured in this article: Los Angeles, CA.