Article No: 116
Oklahoma concrete professional creates a tilt-up surprise
By: Carole McMichael
Photography by Errol Russell
A visit to Errol and Susan Russell's home in Edmond, Okla., is like a visit to a country estate set on gently rolling, grass-covered grounds. Everywhere there are stands of trees, and on one side, a quiet lake that meanders around a small island.
The 4,000-square-foot, single-floor design mixes elegance and comfort with rich colors. It includes a kitchen; a family room and living room, both with fireplaces; a formal dining room; three bedrooms; a gazebo-shaped mother-in-law suite with a patio; and a master suite with a cathedral ceiling, sitting room, fireplace and koi pond outside the master bath.
The house reaches out in several directions. The 1,000-square-foot, three-car garage with a large storage area, is angled to hide the doors from the street view, and at the opposite end, the master suite is set at 45 degrees to the main house. There is an inset on the east side that works around a tree, and a bay window for the "his and her" office that bumps out at 45 degrees. A brick walk leads up to the front portico, which is flanked by the bay window with a metal roof and the large living room window with a distinctive roll-top arch.
The most eye-catching feature of this house is the rock and mortar exterior, but, perhaps the most unexpected feature is that it is built of tilt-up concrete.
What does the phrase "tilt-up" bring to mind? Probably any number of commercial buildings — strip malls, convenience stores, warehouses and offices. They usually have clean, rectangular lines and some textured finish or stucco look on the exterior. They look good, but how many people say, "I want my house to look like that?" Not Errol Russell, vice president of E.V. Cox Construction Co. in Edmond, Oklahoma.
Make no mistake, Russell, who has been with E.V. Cox, a commercial tilt-up construction firm, since 1979, is a big fan of tilt-up systems for commercial projects. He likes its design flexibility and the durability of the concrete, producing a solid building that is resistant to all elements. But for some time, he has been wondering just how these advantages would work in a home.
"Building a tilt-up home is something I have always wanted to do," Russell said, "And there was the intrigue of trying to take the commercial element into the residential. There were not very many concrete homes in our area, but one of our superintendents had built one of tilt-up, and he was pleased with it."
Packed with challenges
The primary design objective for Russell and his wife Susan was to build a totally handicap-accessible house that would be home to Susan's mother as well. The first challenge was coming up with a plan that he and his wife could agree on. They began looking at plans and finally discovered one online that came close. Next, Russell worked with an architect doing a cut-and-paste job from various plans that gave them all the features they wanted. That included the wider openings for rooms and closets, and for bathrooms and halls, providing his mother-in-law with the maneuverable space she would need.
The next challenge involved the preplanning for the erection process, which was key to limiting waste. (When the panels were set, Russell only had one that needed cutting.) The president of E.V. Cox was a structural engineer, so he handled the engineering details for lifting stress, rebar placement and connection points. Russell designed the panels, which involved making a number of decisions in advance. For example, he had to buy the windows so he could build a template off the window that would affect the layout of the panel.
"We like the appearance of rock, so we decided to use a rock exterior," Russell said. "Getting it to look the way we wanted was the next challenge. I had to find the rock we liked — I chose a stone called "riprap." Normally it is used in drainage areas to slow down water movement. Once we got the rock that we would put into the forms, we had them cull out those in the wrong color or size. The culled rocks were later used to line the edge of the lake we dug in the drainage area."
Before Russell started building, he did three test panels, 5-foot square. Each used different rock, different brick and different techniques. Then they were raised, cleaned and grouted so he could get the precise look to the finished rock face that he wanted. After that, he bulldozed them and went forward with the erection.
"The first thing we did was to lay out footings to know where they were going to be," Russell said." The footings themselves were not going in until later to keep them nice and clean. Then, having leveled the spot, we put the edge forms for the panels on the ground, put the bed of sand in, placed the rock one at a time on the sand and added a little more sand between the rock. For the window sills and headers that used brick trim, we cast the brick right in with the rock. Each panel has it own casting bed. We used 2-by-10s, so the panels ended up being 9 1/4 inches thick. You have to make sure the panels are the correct size, so I check every one before the pour.
"Next, according to what the engineer determines, we place all the welding plates and rebar in the forms. Every panel is a little different. Some use No. 3 rebar, some, No. 4. The spacing depends on the size and the way the lifting inserts went in. The rebar is tied together and the lifting inserts are tied to the rebar. Most panels have four inserts for lifting. We also have steel point embeds on the panel (for welding the panels together top and bottom after they are set). Next, the concrete is poured into the forms. At this point, the crew put in the 2-foot wide footings, which will extend 2 feet below the floor level of the house.
"To finish the rock exterior of the panels, we removed the sand with a high-pressure power washer; then, each rock was individually grouted by hand with a masonry mortar between the rocks. We used a standard mortar mix with a plasticizer, but no stain; and a chip mix, which is three-fourths aggregate, to produce better flow and make it tighter. The big thing with mortar is that you buy all the same premixed mortar to have consistent shading. Some chipping was done on the rock so we could add smaller rocks to camouflage the joints. Then, once we were through that process, we went through with waterproofing material, so water wouldn't migrate through the mortar and cause it to delaminate. Rock gives you an irregular surface, so little imperfections don't show."
The panels, which have to get up to 3,500 psi — the strength required to pick them up — take about a week to cure. After about half the panels have been poured, a crane lifts them to make room to lay out and pour the rest. Each panel is set in place, then welded to the next panel and then the floor is poured.
"We set up between eight and 12 panels a day," Russell said. "The family room fireplace panels were the most challenging two pieces to build. We did the fireplace with the 24-foot chimney out of two panels - we brought in the front half and then set the back half. I had a brick layer come in and do a 3-foot brick cap which was set in on top of the chimney on the exterior."
Once the shell of tilt-up panels was in place, the interior framing proceeded using conventional techniques. The only interior walls using tilt-up were for a saferoom doubling as the master closet, which took advantage of exterior corner walls. Russell added a concrete ceiling to create the saferoom capsule. The inside panels were then sheet-rocked and the ceiling concrete was textured. Other interior use of concrete besides the family room fireplace, includes: the kitchen and family room floors, which used stained and polished concrete, scored to resemble 18-inch tiles; and a stone-faced panel surround in the kitchen.
"For the roof, we used conventional trusses, but they were built in place," Russell said. "We put a 2-by-8 treated member on top of a concrete panel and nailed into the panel. All the load of the roof is on the ceiling joints or interior walls, so there is no lateral force applied to the panels. We finished the roof in shingles to be consistent with the look of the neighborhood."
The framers set 2-by-4 studs 6 inches in from the panel and built the interior walls to receive insulation, electrical and plumbing. For insulation, Russell chose an open-cell spray foam sprayed directly on the walls and ceiling.
According to Russell, the only problems involved the framers' attachments on the windows. He had 2-by-8s attached to the top of the panel so the framer would have something to nail onto. The framer also had to figure out how to bring the soffits into the concrete. After he got his boards in place, possible voids were closed off with grouting.
Getting inspector approval for concrete homes is happily not the problem it used to be. "Code inspectors only wanted a structural engineers' seal," Russell said. "Once they had that, they didn't bother me until we got to the garage floor. The code for the garage requires the floor to be 4 inches below the house floor so no fumes can get into house. But for handicap purposes, I put the garage doors 4 inches below and sloped the floor up to the house entrance. We had to negotiate that. At the house entrance, I had to put in a heavy-duty steel door with hinges that make it close automatically. I also had to install an exhaust fan in the garage. With the slope, any fumes would go down toward the doors. What I did met the intent of the law, so we came to an agreement."
After a year
"After living in this home for a year, I can say we still like the final result," Russell said. "I wanted to prove you can build a tilt-up home that wouldn't look like a typical tilt-up building. Every person who drives by would think that the rock was all laid by hand. Also, we are doing really well on energy economy. Building my home this way was definitely more costly when compared to stick built; however, if I factor in the cost of having a stone mason add on the full rock exterior, it would have brought the cost close to what it was."
Russell chose to do onsite tilt-up construction because that is what he does, but if there were to be a next time, he would explore using casting plants that could do the panels more economically and quickly.