Article No: 136
The New Prairie Challenge
By: Carole McMichael
The many Frank Lloyd Wright tours that draw enthusiastic crowds every year throughout the country are a testament to the enduring quality of Wright's architectural philosophy. The tours include the work of his apprentices and of new architects that carry on his design concepts. The Wright association affiliate in Wisconsin asked Ken Dahlin - a two-time award-winning architect, mostly for Frank Lloyd Wright-style homes - to put his New Prairie home as a model in its two-day tour. Sign-in notes included comments such as "Great house," "Wonderful house," and "I'm interested in looking at one."
New Prairie, which is in the River Meadows subdivision in Racine, Wis., was built by Picasso Builders - a name that suggests homes should be as much art as shelter. Bill Schmidt, vice president and builder on the project, takes his "art" seriously. He finds that the insulating concrete form is the right material for this approach.
"I've been researching concrete construction and watching ICF forms since they came out in the 1980s," Schmidt said. "In the beginning, some systems were pretty delicate; there were people who were not trained in installing them properly; and some ICF companies did not develop specialized attachments for their product. Since then, I have been watching them improve.
"Within the last year, there has been a large influx of ICF construction in this area, directly related to the Phoenix Systems' product and the salesperson Robert Mathiesen. He has been in the business more than 30 years and is very knowledgeable.
"Mathiesen walked into Phoenix expecting to blow them out of the water, but he walked out being their salesman. He really believes in the system and knows what he's talking about. He comes in and says, 'I have looked at all these forms, and this one is it.' I tried it based on that. Phoenix forms answered all the questions I had posed and addressed them in one way or another. Builders are going to have to overcome some resistance to new forms, but I truly believe it is the wave of the future - concrete is going to be the medium almost everywhere."
The building challenge
Because Schmidt looks for improvements in materials and techniques, he expects to encounter new challenges. The biggest challenge of the New Prairie home was marrying three new technologies: the Phoenix ICF, the Lite-Deck floor system and the Ultra Seal wall finish from Global Coating.
"Each of these products has an installation process from the manufacturer," Schmidt said, "but when you work with multiple products, you have to adjust these procedures to account for the other ones. For example, when I put window bucks in the ICF wall, because the windows are set back, I had to wrap them in Ultra Seal by spraying the product on before the windows went in - in others words, change the procedure.
"It was the same for the Lite-Deck. Normally I do footings, run ICFs and then put a floor system over it. In this case, I ran the footings and ran only one course of ICFs, poured the wall and poured the basement floor at the same time. Instead of backfilling all at once, we backfilled half the foundation so it was high enough for a man to stand to set the Lite-Deck panels. After we poured, we then backfilled the other half.
"Adjustments are mostly common sense. If, in the beginning, you have done your homework and involved the proper people, some things just become evident. The first time you try marrying a lot of new stuff, it adds a lot of time. To help other builders, I have been asked to do a builder-friendly CD on building with these techniques."
The New Prairie house began with the architect, the engineer and Schmidt working out many of the details introduced by the newer technology. Schmidt then held preconstruction meetings at the architect's office with manufacturers and all the subcontractors involved with concrete, framing, plumbing, electrical work and heating, ensuring they understood how they would work with the products. For example, the electrician would need to use the 1600 box that sets in the polystyrene of the form at the perfect depth, rather than the normal 3-inch, nail-in plastic box. According to Schmidt, these little things are important to preplan. If there is no complete answer in the preplanning stage, he at least works out the rough details. After 28 years of working with all kinds of new-stuff challenges, he gets more than a few "How-do-I-fix-it?" calls from other builders who were not as thorough upfront.
Cost is always a factor, but particularly so when subs are new to a system. Schmidt, who has used the same subs on all the jobs, set up a special deal for this project. "We are going to do one of these ICF houses," Schmidt said, "and there will be a set price that we are going to live with on this project, but it is not locked in for the future. After it's done, we will re-evaluate and readjust the price on the next ones. Naturally, this first one took longer and we didn't come out with a large profit. If the subs send me the same guys for the next project, they can take advantage of their experience, and it will go faster. After we finished the New Prairie home, some subs went up on their pricing and some stayed about the same. It was guess work, but calculated guess work.
"Mathiesen trained me, and I pretty much trained all the subs. Training the erection crew was pretty simple. The block was actually designed so homeowners could put it together themselves. You do not need a concrete crew - a framing crew could do it because it goes up so easily. My carpenters worked on the first project, so they are now certified to build an ICF basement. Some concrete companies who don't want to lose market share are picking up on this."
From the start
ICF construction doesn't call for any unusual site evaluation. Because this subdivision already had houses built in it, Schmidt did not have to do soil borings. The soil was solid, hard clay, running 5,000 psi or more.
"New Prairie is a 2,700-square-foot, one-story house," Schmidt said. "The foundation and exterior walls are built of the Phoenix ICF system. It has a standard rebar layout, but depending on the height of walls, type of headers and down forces of the trusses, a structural engineer figures out placement of rebar. We used the regular-sized Phoenix block - 16 inches tall and 4 feet long. It gives me a lot of latitude. If I want a certain height, I can cut the block to fit. The form has a chair for the rebar to set into and polypropylene ties [that have twice the pull-out strength of most other ICF ties, according to the manufacturer]."
The house has three bedrooms, two and a half baths, a great room, a dining room, an away room and a laundry room on the main floor. There is a full bath on the lower level, which also includes two offices, an exercise room, a kitchenette, a game room and a large rec room. The house's exterior finish is brick and Ultra Seal, a rubberized, synthetic stucco coating that doesn't break and is easily repaired if a hole is accidentally made. Ultra Seal is meant to go over foam, making it a perfect partner with ICF construction.
Step by step
"After the excavation, the footings are set," Schmidt said. "The size of footings depends on engineering. Because of the Lite-Deck floor for the main level, the concrete mass was greater than normal. The Lite-Deck panels range from 12-inch thickness up to 18-inch thickness, which is what we used for this project. Once you get over the 14-inch thickness, you need extra engineering rebar because the weight of the concrete is working against you. We erred on the safe side, but for the next house I do, I won't be using the 18-inch."
A hydronic radiant heat system provides heating on all the floors and in the garage. There is plenty of adjustability - the lower level has three control zones; upstairs, there are five zones; and in the garage, one. The tubing was installed for the lower level slab, and one course of ICFs started the wall. After the rebar was set, heating tubes were stapled on top. A concrete wire mesh was laid over them so the tubes would not float up, and micromesh (taking the place of wire) was mixed into concrete to strengthen it. Finally, the first course of ICFs and the slab were poured all at once.
Next, the rest of the foundation ICF walls were stacked and poured, and the Lite-Deck panels, which house the hydronic radiant heating system for the main level, were set to create the floor and braced underneath with vertical shoring. The process with the radiant heat tubing was repeated. Rebar was then drilled into the top of the Lite-Deck where the walls would stand, and the forms were set for the above-grade walls.
When the first course reached the proper height and was braced laterally, the carpenter came back and snapped chalk lines on the foam for the interior and exterior walls, allowing the electricians and plumbers to determine the proper placement of the PVC sleeves in the deck and walls. When the Lite-Deck pour had set the proper time - 21 days - the shoring was removed. Schmidt cut a 4-inch-by-4-inch grid of control joints into the floor surfaces and stained them with powdered dyes to use the concrete surface as the finished floor.
"To attach the ICFs to the footing, I use a foam adhesive in a gun," Schmidt said. "It is squirted onto the block as well as the footing. In three to five minutes, you can't move it. Then the individual blocks, which connect with a ship-lap joint, are glued together with the foam, although they would fit together tight enough without any glue. I can construct a whole wall in my shop and transport it to the site if the weather is nasty and it is a short piece, but I prefer to do assembly onsite.
"How long it takes to put up the forms depends on the number of corners in a design. By the time I do two corners, I could set 20 feet of straight wall. If you design your ins and outs to use the Phoenix corner block, it goes much faster. With an experienced crew of four or five, you should be able to set up a system, braced and ready to pour, in four days. It sets in seven to 10 days, but the bracing can be stripped off the next day, and carpenters can work within three days."
Phoenix Systems has been on the market only a few years, but Jay Williamson, who developed the system, is a true ICF pioneer. He's been involved since the conception of ICF forms. He would invent a system and sell the rights - and then continue working to make a better one, and then sell that. The Phoenix System is his latest version, and one he decided to keep.
For more details, visit phoenixicf.com.