Article No: 263

2009-11-17 11:17:43
By: Larry Storer

Photography by Provis Media Group
North Carolina custom home builder Mark Johnson completed his first insulating concrete forms (ICF) house this year, and in August got word that the US Green Building Council (USGBC) has LEED-certified this home with a Platinum rating – only the second Platinum-certified residence in North Carolina and one of just a few in the entire country.

This remarkable house, located directly on the coast in the Wilmington community of Landfall, is truly a sustainable green house – from the LOGIX insulating concrete forms (ICFs) to the 1,800-gallon underground cistern that harvests and stores rainwater and runoff from the house for reuse in landscape irrigation.

Work on the foundation began Sept. 30, 2008, and the house was finished in May. In the two months after the house was completed, time was spent going over each Leadership in Energy Efficient Design, more widely known as LEED, requirement to be sure everything was correct, and several LEED inspections and tests were done. The rare, coveted Platinum certification was announced in August.

Kevin Johnson, Mark’s brother and a principal in Mark Johnson Custom Homes (, said that the key to the success of this project was having a great team of trade partners. “Everyone was happy to step up and do something new and it really was a fun project.”

The house involved a steep learning curve, but it wasn’t learning how to build with the ICFs that was the real challenge. Johnson said the biggest learning curve was in mastering the LEED process because it is still a relatively new program to many residential builders and suppliers.

“Some of our vendors and suppliers were confused about LEED because there are multiple rating systems for commercial and residential construction. Things that you can get X-number of points for on a commercial project, you can’t get as many points for on a residential project. For example, you can get 6-7 points for a cabinet system on the commercial standard, but only 1 or 2 points for the same cabinet system on a residential project.

“The biggest challenge with LEED is education and I feel like my next LEED project will be a breeze,” Johnson said. “Once you understand what they are looking for, it is a fairly easy process.

“Because it was a learning experience for us with both the ICF method and the LEED process, a spec home was an appropriate fit for us to try these new technologies. There were times we had to stop and regroup and get the entire team together to make sure we were addressing things early in the building process. If we got to the end and ran into major construction delays, we really wouldn’t feel comfortable doing that on somebody else’s dime.”

    The Johnson brothers knew of ICFs, and because of their location on the coast with its storms and hurricanes they were interested in building with concrete. They attended a Concrete Technology Symposium in Charlotte, N.C., where they renewed a friendship with Buddy Hughes, LOGIX regional manager for North Carolina.

“We hung out with Buddy on that trip and learned more about his products, checked out some competing products and had the most comfort with Buddy and LOGIX,” Johnson said. “We decided when we got back to go ahead and build this house using LOGIX ICFs.

Once they got into the project, he said they decided that this house really did have the potential to be a green home. They decided they were going to go into the LEED program, register the house with the USGBC and start building.


    LOGIX did a one-day training session with the supplier Probuild in Wilmington, bringing in the Johnsons and their mason for instruction on how to set the system up. In addition to a hands-on demonstration, LOGIX introduced the Johnsons to a consultant who came in for two days when they hit the major phases with the ICFs so that they didn’t pour a wall and run into a problem after it was too late.

“The process was a lot of fun and it was different from what we were used to,” Johnson said. “We certainly could have done stick framing and moved through it more quickly, but now that we have the experience with the ICFs, we can do it just as fast as stick framing.”

Up to 50 percent of LOGIX blocks, by weight, are made from recycled materials, and the ICF product produces minimal waste, which can then be fully recycled. LOGIX foam panels are made from 10 percent recycled expanded polystyrene (EPS) foam. LOGIX webs, which hold rebar within the form, are made of 100 percent recycled polypropylene.

Building with the LOGIX ICF delivered the first 26 LEED points by itself.

Johnson said the exterior walls are a foot thick: 6 inches of concrete sandwiched by 2 3/4 inches of LOGIX foam panels on each side, providing an R-50 insulation standard.   

The 114 cubic yards of concrete used to fill the ICFs was provided by Hughes Ready Mixed Co. in Wilmington, and was a 30 percent fly ash mix.

“If I were building a home for myself, I certainly would build it with ICFs, especially in this coastal region where we know we are going to get hurricanes and other storms.”

Johnson said this was a good house for their first ICF project because there was nothing in its design that was difficult (click “Green Building” on the web site). “We have a couple of 45-degree walls, but that was it.”
Two additional major factors in achieving the 90-plus LEED points required for the home’s Platinum rating are indoor air quality and water efficiencies, and Johnson said he believes that it was in these areas that they were able to break into the Platinum range.

The water efficiency systems will benefit the homeowner’s wallet and reduce demand on the city’s water, sewer and stormwater systems.
“One of the most exciting things we did in the house was on the landscaping side,” Johnson said. “We buried an 1,800-gallon cistern in the backyard that collects heavy rain and roof water runoff. For the actual irrigation setup, we believe we were the first around here to use a product called Netafilm (, a total underground drip system.

With the Netafilm system, there is no water lost to runoff and no water lost to evaporation, and the water is placed exactly where it’s needed – at the roots of the grass. The system uses rain sensors so the homeowner doesn’t water when the roots are still moist.

The city also benefits from the way this house manages its water. “In Wilmington we have a ton of problems with our sewer system and we actually had a building moratorium two years ago where they just stopped issuing building permits so they could upgrade the sewer system. And the way we set up the landscaping, we’re able to really protect our sewer system by keep all the water on our lot.

A neighbor uses 2,000 gallons every time he waters on his same-size lot, compared to the 382 gallons every time this lot is watered, and this does not include any water that could be used from the cistern.

Water savings inside was a major LEED issue as well. The Bosch dishwasher uses less than 6 gallons of water on a standard cycle. All bathroom fixtures are low flow, and toilets are dual flush, with one button using less water than the second button, depending on need. A standard toilet flushes about 2.5 gallons of water, while with a dual flush toilet, the number 1 button flushes less than a gallon of water and the number 2 button flushes 1.6 gallons. Kohler estimates a dual-flush toilet could save an average family up to 6,000 gallons of water a month.

Another major LEED issue is managing the indoor air.

The ICF home is so tight that a two-stage HVAC system processes fresh air through sofit vents into an Energy Recovery Ventilator (ERV) where it is conditioned before it travels to the 17-SEER HVAC unit. This puts less stress on the main HVAC system to cool the hot, humid air.

There is a return vent in every room (except the kitchen, laundry room and baths) that facilitates the removal and replacement of fresh air in the entire house 35 times every hour.

“The fact that there are no VOC paints, very low VOC stains, and no off-gassing from carpets and carpet pads really contribute to the air filtration value of a healthy home,” Johnson said.

“All bathrooms have almost inaudible exhaust fans that have occupant sensors. So, when you walk in it turns on and when you leave it activates a timer that shuts the fan off in 30 minutes.”

The same feature, but with a bigger fan, is installed in the garage and operates when the garage door is has been open and then closes. It draws out the noxious fumes that a car continues to emit, even after the motor is off, as well as fumes from yard equipment or other chemicals that may be in the garage.

This four-bedroom, 2,750-square-foot house is built on two levels with a two-car garage in the front and a large open terrace and smaller covered terrace in the back. The professional landscape is maintained economically using water from the buried cistern and the root irrigation system.

The main entrance is from a covered porch into a large foyer, which flanks a formal dining room with a tray ceiling and custom columns, and opens into a great room. The great room has a tray ceiling, built-in entertainment center cabinets, a gas fireplace with marble surround and a decorative mantle. Doors lead to a raised terrace.

Hardwood floors are in the great room, dining room and foyer, ceramic tile in the kitchen and baths and carpet in the bedrooms. Above the upper level ceiling is blown-in cellulose made from recycled paper that insulates to an R-40 standard.

The downstairs master suite, which opens to the great room, has an additional opening to the outdoor terrace, a tray ceiling, his and her walk-in closets, a bath with a whirlpool tub, a tile shower, and double sinks in a granite countertop. Two additional bedrooms with full baths anchor the front corners of the main level.

The large kitchen is on the left side of the main level and has a breakfast area that opens to the smaller covered terrace. It has granite countertops, an extended center island, and built-in Bosch appliances. Coming in from the garage, there’s a laundry room and mud closet for shoes to keep tracked dirt and contaminants out of the house.

The upper level is a 12-by-24-foot fourth bedroom with a full bath, closet and storage area.

Given the advantages of ICFs over stick building, being a certified ICF builder has opened up new possibilities for the company. “We’re talking with a lady right now who is going to be moving down from New York and she may want to do an ICF house in Curry, N.C.

With the ICF insulated walls, low U-value and solar heat gain windows and doors, Energy Star-rated Bosch appliances, an energy-efficient HVAC system with its ERV system, and a tankless on-demand hot water heater, the estimated cost of electricity and gas to operate the house is $1,763, a projected savings of $2,276 a year on electrical and gas utilities.

The 17-SEER Trane HVAC system has programmable thermostats. “It’s humidity that really controls the comfort in a room,” Johnson said, “but most thermostats cause the system to come on when the room reaches a certain temperature. This has a feature that when the humidity in a room reaches a certain point, it will go ahead and kick on to pull that moisture out of the air.”

LOGIX ICF walls have superior fire and sound attenuation ratings. A 6.25-inch LOGIX wall meets a 4-hour fire rating and has achieved a Sound Transmission Class (STC) rating of up to 56 out of a possible 60. An STC is a number rating of a material ability to resist airborne sound transfer at the frequencies 125-4000 Hz. In general, a higher STC rating blocks more noise from transmitting through a wall.

“The ICFs themselves have a great insulating factor of R-50 and therefore air conditioning and heating costs are considerably less than other homes. The fact that noise is virtually eliminated; that ICFs have an excellent fire-resistance rating; that ICFs are resistant to insects and mold; and that the house qualifies for lower insurance rates all make an ICF home an exciting product,” Johnson said.

“While no home is a hurricane-proof home, walls on an ICF home are rated at 250 miles per hour, so it’s a great advantage that a 2-by-4 that is airborne at 250 mph is not going to penetrate the wall.” The cedar shake roof is built to coastal building codes.

The house is listed at $624,000, and Johnson believes that this home’s solid construction, green features, healthy interior and nationally recognized environmental and achievements justify the price.

“There certainly are houses in Landfall that are a similar size or larger that might be on the market for less, but we believe this house should be priced at a premium because of the extra value of the concrete construction, reduced utility cost, water savings and management, outstanding air filtration and conditioning, and other environmental products. It’s also the little things here and there – premium cabinet stain, no VOC paints, and carpet and padding that gives off no off-gassing – that adds to the home’s value.”

Johnson estimated that it cost about an additional 9 percent to build the house to the LEED Platinum standard, and he said he recognizes that these features appeal to a particular kind of person.

LOGIX’s Hughes, who got the ball rolling on the ICF part of the project, said he thinks this house represents a great achievement for the concrete building industry.

“They have done a great job of putting the plan for this house together, and have set high standards for what is a smart, healthy home that is historic in its state and national LEED Platinum rating,” Hughes said.

“They just did so much research and due diligence before they started and throughout the project that most builders just aren’t willing to do. They’re the future of the building industry.

“I think we have learned from the reality of the last year or so that we have to build smarter than we have for the past 20 years, and these guys are just a couple of steps ahead of anybody else.”