Windom Hill Place

Pittsburgh developer and builder Ernie Sota has been constructing environmentally friendly buildings for three decades. He’s been LEED (Leadership in Energy and Environmental Design) accredited by the U.S. Green Building Council for five years and serves on the board of Pittsburgh’s Green Building Alliance. A few years ago, his company, Sota Construction Services, built the Carson Retirement Residence/Sarah Street Apartments with insulated concrete forms (ICFS), choosing them for their insulation value and sound blocking qualities—both green attributes.

So when Sota was ready to build Windom Hill Place, luxury townhomes on Pittsburgh’s South Side, he decided to use ICFs once again. “I was interested in ICFs for several reasons,” says Sota. “I thought they provided a good marriage of structural response to the hillside conditions and thermal mass.” They also provide a high level of quality for the building, he says.

Tough Terrain

Perched on Pittsburgh’s South Side Slopes, above the Monongahela River, Windom Hill Place was designed by architect John Martine of Strada LLC to evoke the hillside homes of European cities like Budapest and Prague. The first phase of the project, completed in November 2006, consisted of one structure with four units. Sota plans to build another five-unit building on the site once those first units are sold.

Each 2,800-sq. ft. unit includes a ground level garage, a living room and kitchen on the first floor, a second floor level with two bedrooms and an expanded master suite on the top. The interior of each unit is clear span, so the people who buy the homes will have the flexibility to configure the units to meet their specific needs.

The townhomes incorporate many green features, including cork and bamboo floors, EnergyStar appliances and HVAC system, low VOC paints and plenty of natural lighting. The floor-to-ceiling windows provide spectacular views of the city below. A balcony on the fourth floor, made from structural concrete, can support a hot tub, a small garden or even trees if the homeowners decide that they want to add some green features to that living space.

The terrain was difficult to build on. “The rear of the building has 20 feet of back-filled soil; the hillside isn’t even walkable, it’s basically straight up and down,” says Bruce Cody, PACA’s concrete promoter for Western Pennsylvania. He worked for Sota Construction Services during much of the Windom Hill Place construction.

The rough terrain was one reason that the builder decided to use ICFs. “The structural situation lent itself to a poured concrete building because you can use the building as a retaining wall, to hold up the soil behind the whole building,” Cody adds.

Canadian-based Arxx supplied the ICF forms, which were manufactured in the company’s Pennsylvania plant. Frank Bryan Inc. of Pittsburgh supplied the concrete. The project required 320 cubic yards of concrete, much of it with a fly ash component that made it a greener product.

The thickness of the concrete walls varies by floor. The first two stories in the rear of the building have 10-inch thick concrete walls plus two and a half inches of foam on each side, for a total thickness of 15 inches. “Above the second floor in the rear we stepped the walls into a six-inch concrete wall. The entire front of the building was done with six inches as well,” says Cody.

The plan to use ICFs as the retaining wall for the hill did not work out, however. “We had thought that if we did the retaining wall during the winter construction season, the hillside would freeze up enough so that we could get it excavated and get the building up,” says Cody. “But in mid-January there was a two-inch rain storm after it was excavated that brought the whole hillside down. It buried the site. The only way to continue was to wait for spring and put in a soldier beam and concrete plank retaining wall the whole way across the rear of the site.”

Fast Work

Although site preparation was a challenge, most of the ICF work was not. Laying out the four-foot-long blocks required only five or six workers—one experienced lead person and carpenters. “You just have wasted man hours with too large a crew,” Cody says. “Carpenters are usually best suited to build with ICFs because the work involves wall forming, which they are used to doing.” That includes measuring properly for door and window openings as well as for where the floor systems will go for the next level of the building.

“Generally speaking, it took about two weeks per story to get the building up,” Cody continues. “A lot of it was because of the big window front and big openings—there’s a lot of work in that. It was not just a box; there are offsets in the building, and each unit steps back. There was a lot of steel reinforcing in the rear wall because of the amount of backfill that it was designed to support.”

That steel reinforcing required some manipulation of the ICFs. “We actually had to hand form a 24-inch exterior concrete beam around the building,” Cody says. Locating the beam on the inside of the building was not an option because the space in the rear was needed for an elevator shaft. “So we cut the ICFs in half, inserted the steel [cages of number eight rebar] and formed the exterior of the building with plywood in those areas.”

Once the ICFs for an entire floor were ready, it took about six hours to fill the forms with a standard 4,000 psi wall mix concrete. On the exterior, crews covered the first two layers of ICFs with split face block (cast stone with recycled content) and the top two with recycled metal panels. Drywall covers all interior walls. “The building code won’t allow the foam of the ICFs to be exposed on the interior,” Cody explains.

Environmental Positives

The use of ICFs in the construction of Windom Hill Place will offer a particular appeal for people who believe that green building is important—and who want to save money in energy costs over the long term.

“ICFs are very big in the green building world because the forms themselves are 50 percent recycled,” says Cody. Although the expanded polystyrene foam used in the blocks is not recycled (or recyclable), there are polypropylene webs inside the form that hold the polystyrene together. The polypropylene is made from 100 percent plastic. Because those webs make up more of the weight content of the block than the foam does, the ICFs are considered recycled materials.

The ICFs will also help keep the energy bills low at Windom Hill Place. In combination with the special double-paned windows and a high-tech energy recovery ventilation system that Sota has used, the thick, insulating ICF walls should bring homeowners a 60 percent savings over what they would pay in a comparably sized, conventionally built home.

There are drawbacks to the technology, however. Even thought they save money over the long term, homes built with ICFS cost more than those built with a wood frame. That has made these units, which start at $575,000, a tough sell in the Pittsburgh market. (PMI Mortgage Insurance Group has rated Pittsburgh as the most undervalued home market in the country.)

But Sota believes that ICFs were the right choice because of Windom Hill Place’s location. “If I had not used ICFs, I would have used poured in place concrete or Ivany Block, and each would have been as expensive or more expensive than the ICFs.” He still plans to do the next five units of Windom Hill Place with ICFs and, though he doesn’t have any other building projects using them on the drawing board at present, he says, “I will certainly do ICF again.”