Article No: 202
Tackling Californias energy crunch
By: Carole McMichael
Photography courtesy of Kent Yonkers,
concrete supply specialist
El Dorado Hills, California, sits in the hot, dry and windy foothills of Sacramento Valley, qualifying it as a wildfire zone. Considering the two- to four-hour firewall achievable by having an exterior concrete shell, you would think the area would be a showcase of concrete-built homes; but that is not the case. Even Greg Welch, contractor/builder of Nor-Cal Construction, only recently moved from his stick-built home to one he built of Arxx ICFs.
“We had a pretty big fire here in August that got within a third of a mile,” Welch says. “I was not very concerned because of the concrete walls, stucco and the all-tile roof on the house I have now verses the house I just moved out of that had a shake roof and wood-siding exterior.”
The danger from fire, however, was not what prompted Welch’s decision to find a better building system. It was the cost of energy. That also inspired other builders; shortly after a serious energy crunch three or four years ago, concrete homes made their debut. Welch’s concern about that monthly electric bill fell right in line with his wanting to check out how an above-grade concrete house would perform.
“I was tired of the twisting and rotting of wood,” Welch says, “and being in concrete, I knew it was a better material for building. After living in my own concrete home, I’m learning of a few more benefits. It is a lot quieter. We have really heavy winds and there is no creaking. It also is very comfortable.”
Choices and benefits
Welch worked with a lot of concrete block while building retaining walls, but hadn’t built a house. It seemed like the ICF was a great choice, but before he picked a specific brand, he researched 10 different ones. His selection of the Arxx Block was based on price, availability, and his design. Availability may become a deciding factor if distributors are a long way from the building site, increasing trucking costs. Also, brands that have only a single source may make availability key.
The Arxx ICF blocks are 4 feet by 16 3/16 feet. Welch used corner and 45-degree blocks as well as the standard forms. For rounded walls, he cut the inside foam in several places, bent it and taped it to create the desired curve. To get prepared, he read up on the ICF building process from in the Arxx manual, and got a few technical pointers from Arxx reps on things like the way to screw on the plywood for the corners.
There are not many people in this area experienced with ICFs, so Welch mostly brought in some of his company concrete crew members. They had never worked with ICFs before, but they found it easy as long as they had an experienced leader.
“It is basic building,” Welch says, “just like with cement block. You just have to learn to support the walls. The Arxx rep helped here and there—he was here five times to get me going and he checked before the first pour. Mostly it was fun to put the blocks up. You get so much done you can’t keep the stacks near you because you put up the wall in 15 minutes.
“There is another benefit to building with ICFs. I knew once I poured a wall, it wasn’t going to change or twist. With wood, you put up a wall and three weeks later when you go to put up sheetrock, the walls are all crooked.”
Living in style
Welch decided on formal Italian as the design for his 7,000-square-foot home, finished in stucco and topped with a 4/12-pitch hip roof with real clay tiles to keep the style authentic. The floor plan provides ample space for a daylight basement; a main level with a front entry, the kitchen, pantry, living room, dining room, master bedroom and bath, family room and office. Add to that three different garages—one for Welch’s car hobby. Two of them are underneath the house, and one is on the main level.
Off the entry, there are two stairways going down and one up to the third level. The downstairs basement is cut into the pad as a 13-foot-tall retaining wall. It looks like a two-story home from the front and a three-story from the back. The basement centers on a 30-foot by 60-foot game room, with a wine cellar, a guest bedroom and bath, an exercise room and quite a bit of adjacent storage. The third level has two bedrooms and a bath for the kids, a media/computer room and the kids’ own laundry room.
“My basement floor is saw-cut and stained concrete,” Welch says. “I love it. We have a 12-inch border stained darker than the center. We had some cracks, but most designers say that is part of the character. Being a concrete contractor, I didn’t like that, but I’ve come to accept it. We also have a set of stairs that have stained concrete risers and treads. I used a lot of precast as well in columns, windowsills, trim and baseboards. I have a 1,000 square-foot, exterior second-level, stamped and stained deck, sitting on concrete columns.
“The house is positioned for the view,” Welch says, “We have a view of Folsom Lake and all of Sacramento Valley city lights, from the coastal range to the bay area. We see sunsets like crazy. For that reason, we tried to get every room possible to have a view. There are about 80 windows in all, including a bay window in the office, 8-foot-tall and 12-foot-wide windows in the family room, and 8-foot-tall sliders. In the front, all the glass was set to the outside with precast trim and sills. On the inside, it has 10 inches of sill space. In the back, I put the glass in the center, 6 inches on each side and just wrapped the stucco around with no trim.”
The Welch house sits on an acre-and-a-half lot with about a 10-degree slope. “The soil is all rocky soil that is good for drainage and for building,” Welch says, “until we hit rocks—lots of humongous truck-size rocks. The only thing we could do with some of them was drill into them and blast. We used many smaller ones to build a rock retaining wall, but still had enough to send 18 truck loads of nice-looking, moss-colored boulders away. That 13-foot cut for the basement meant moving a Volkswagen-size boulder. Luckily the excavator was able to get most of them out.”
Here and there, according to Welch, there was a big one the size of a house in the way of the footing. He has about 50 feet of footing that is actually rock. The crew could only go about 6 inches deep instead of 16 inches. They drilled into the rock every foot or so and put in the rebar with epoxy.
Lining up the engineer and some of the subs was also a little rocky. “I had trouble finding an engineer who would do it,” Welch says. “But, once I found one, it was pretty simple. The building department inspectors had seen enough of concrete houses and liked them, so there was no friction about what I was doing versus wood. Before my main inspections, I would have my engineer come up, check and write a letter saying every thing was OK and the inspectors wouldn’t even look at it. They said, “I’m glad you know what you are doing.”
Finding subcontractors meant calling and getting a lot of bids. Some bids were so high simply because the subs didn’t want to do it. Finally, he found a plumber, who had done it before and found it to be “no big deal,” and an electrician, who noted that cutting through the foam with a chainsaw was easier than drilling holes in the wood. It took eight tries to get a stucco sub that didn’t have a problem with screwing the lath to the strip on the block instead of stapling. According to Welch, getting subs depends on how busy they are. Many are so busy, they have no incentive to try something new.
After having a core sample done, Welch determined the 33-foot walls and concrete floors only needed footings 3 feet wide and 18 inches thick. The bottom level has a concrete slab, walls, and ceiling. On the third floor, Welch installed a wood ceiling. His design stepped the walls in, so subsequent levels weren’t centered over the concrete walls below.
On the lower level, he stacked 12 feet and used metal studs for bracing, but didn’t find it as easy as he hoped and afterward rented an Arxx bracing system. The lower- level walls used 8-inch concrete cores with 13 1/2-inch widths. The next two floors had six-inch cores with 12 1/2-inch widths.
There is a lot of steel in the walls and the floors—No. 6 rebar vertically at 8 inches on center out of the footing. Then they go to No. 5 rebar every 16 inches in the block. That comes out to 18 tons of steel in the house, a lot of which is in the floors. The main floor, which was 4,000 square feet, was Lite-Deck. He used No. 8 rebar with stirrups.
“I stacked 12 feet,” Welch says, “and poured 4 feet at a time continuously. We vibrated the whole time we poured. The mix was 5,000 psi, 6.8-sack pea gravel made to pour at a 6-inch slump. To attach the Lite-Deck, I set up temporary shoring; then formed up concrete beams and columns. The rebar from all the floor joists went into the top of the ICF walls, so it was poured together. The pouring was easy, but setting up the shoring for 100 yards of wet concrete was hard. It took a couple months setting up for a one-day pour.”
Altogether, the house took 20 months to build. Welch ended up with a spacious home that doesn’t look like a concrete home, but has all the benefits of concrete, including that lower energy bill he was searching for.
For more information, visit rci-arxx.com. CH