Masonry strikes gold with Tuscan Sun
By: Carole McMichael
Photography courtesy of Bost Custom Homes
In an area of North Carolina that features mostly Colonial-, traditional- and French Country-style houses, Prestonwood’s golf community recently added a spectacular 7,300-square-foot Mediterranean estate with an equally spectacular name: Tuscan Sun.
Rex Bost, the project’s designer and builder, not only wanted to build a beautiful masonry home for his family, but also was eager to open a market for the elegant, Old World architecture growing in popularity throughout many regions of the country. The barrel-tile roofing, intricate roofline details, arches, columns and exterior stonework transport visitors to the Tuscan countryside. Bost’s house features a walkout basement and spacious first and second floors, and is crowned by a fourth floor with a small octagonal observatory. From there, you can step out onto a rooftop patio that offers an inspiring view of the verdant golf course fairways, rolling hills, and a delightful guitar-shaped swimming pool.
“On the inside, I wanted to showcase a very efficient floor plan with good flow and lots of angles,” says Bost, president of Bost Custom Homes Inc., located in Cary, North Carolina. “Rooms don’t have to be oversized—that can waste space and create a cold environment that is not comfortable. I wanted it to feel warm and cozy.”
Bost achieved that aesthetic partly by using a lot of natural products, such as antique woods, on the interior. Intricately carved Indonesian doors open to the well-stocked wine cellar, and 200-year-old wood, salvaged from a Delaware home, became part of a ceiling treatment.
“On our hollow wood floors, we used a number of common-grade white oak boards in random widths,” Bost says. “It has a lot of little knots and imperfections. We also had a lot of Pecky Cypress, which I used in coffered ceilings in the family room, and for the walls and ceiling of the music room. It is perfect for acoustics because it has all the pits in it.”
As much as Bost enjoys the old European flavor of interior appointments, he is also attuned to the demands of modern living. The music room, which is in the basement, doubles as a safe room based on FEMA 320 certification requirements—meaning it can withstand high-force tornado winds. It has a hollow-core ceiling, which also is the floor of the foyer above. The room does not completely meet 320 standards because its doors are wooden, but a small storage room off the music room has the steel door required by safe rooms. “In the midst of a major storm, if things started penetrating, we would go into the smaller room,” says Bost.
In addition to the music room, the walkout basement includes a two-car garage (his—there is a hers also) and an adjacent workshop, a little sitting room with a fireplace, a cabana bath and an open space for games. A guest suite includes a bath and walk-in closet. Altogether, the house has five bedrooms, including the master suite on the main floor and three others on the second floor.
To make all floors easily accessible, Bost installed an elevator that goes from the basement to the fourth-floor observatory. It has glass windows all around and glass doors on each floor so natural light enters the elevator shaft whether the elevator car is on that floor or not. The three-tiered banks of windows with a view to the terrace and soaring ceilings continue the feeling of Tuscan sunlight and openness.
Bost became involved with residential masonry indirectly because his father was a masonry and brick contractor and he grew up laying brick. But the primary reason was his curiosity about how concrete homes were built in Florida, the Southwest and in many third-world countries. When hurricanes came through in 1995 and a lot of his neighbors had big trees crash through their houses, he got serious about studying Florida’s masonry block system and ultimately devised ways to adapt it to North Carolina’s needs.
“We have different criteria to deal with, different insulation requirements,” Bost says. “In Florida, typically, they build one-story homes. When they do go up, they go to stick. I wanted to build completely out of block, so I had to develop ways of attaching the roof and floor systems to the block. Also, in Florida, they build on slab; here we typically have a basement or crawl space. So I also had to develop a way to support the first floor above the ground and subsequent floors using the block.”
Bost built the Tuscan Sun home using an HMU (hollow masonry unit) 8 inches by 8 inches by 16 inches. It is made out of lightweight concrete, which uses a type of rock that expands when fired, so it creates little pieces of stone that are just as hard as solid concrete, but a lot more lightweight.
Unlike Florida, North Carolina experiences cold winters, so in addressing the insulation requirements in walls, Bost had to achieve an R-value of 15. He did this by injecting expanding foam insulation—designed specifically for use in concrete—into the core openings that weren’t filled with concrete for structural reasons. The lightweight block is laid like standard block—the vertical cores line up even when offset. Vertical pockets run throughout the wall.
“What I like about block,” says Bost, “is it makes a stronger, quieter, safer and more stable home. We have fewer sheetrock cracks, molding and floor separation and door adjustments. Those are all associated with settling, or more correctly, the shrinkage of the house. When houses are built out of wood, the wood has a fairly high moisture content—15 percent or so. In the course of the first year, the house has gone through four seasons, which could leave a builder a fair amount of warranty work. With block, we have 75 percent fewer callbacks. Once the concrete is cured, it doesn’t move. Everything is somewhat thermally active, but concrete is much, much less so than wood. When my first masonry house homeowner went through the one-year walkthrough, there was only one nail popped by the fireplace.
“Another thing I like about block is that it is thermally efficient. It is really quite amazing how thermal massing works. This past winter, in the basement, we have not turned the heat on once and it never went lower than 68 degrees. The back of the house is all glass, so the block, which faces west, absorbs the radiant energy of the sun in the day, warms up the walls and slowly emits that heat into the house in the evening. Because of a 2-foot overhang that helps protect against the heat and low-E glazing on the west-facing windows, it also will keep it cooler in the summer.
“All clients whom I have built these block houses for rave about the energy efficiency. One client who tripled the size of his house over the previous one found that he only increased his energy costs by one and a half times.”
“My goal, in a nutshell,” Bost says, “was to build a safer house using the readily available materials and tradesmen to keep the price down to the level of a conventional house.”
Bost used the traditional approach to fir out the inside wall during construction of his first masonry house, but it required so much time and energy, it was less expensive to just do a non-load-bearing two-by-four wall with air space in between. This also meant the electrical and plumbing trades and all mechanicals subs could operate as usual rather than having to put conduit in the block. The wood skeleton also allowed for precise positioning of window and door locations on the skeleton. Once installed, the crew erected the masonry walls and transferred the load to the walls. Around the windows, Bost also created a deep shadow-box effect, typical of Tuscan-style architecture.
Bost says that by the time his crew began the Tuscan Sun project, they had streamlined the process so that they could frame a masonry house for a 2 to 3 percent higher cost than a standard brick house. “The first house came in at 6 percent more,” he says. “It isn’t an exact science, but we figure a house can pay back the additional cost in two years—and that is based just on the energy expenses, not reduced maintenance.”
Before the project began, a soil scientist performed a compaction test. An engineer certified the footings, typically 2 feet by 1 foot, reinforced with steel before they were poured. The basement walls were poured using a cast-in-place system because they lack waterproofing limitations of block and saved some time. The walls stepped down with the grade, and then were filled in with block to bring the walls up to the first-floor level.
“Once you stack the block,” Bost says, “you have vertical pockets that run throughout the wall. About half of them are filled with concrete and steel rebar that comes up from the footing just to add strength to the wall every 4 feet on-center. It really becomes a post-and-beam type of construction. At each floor level, we have a bond beam, which is a U-shaped row of blocks that goes around the outside of the house. We run steel rebar horizontally in the bond beam and fill it full of concrete, so we have a solid concrete beam that runs around the house at each floor level.
“The weight of a the wood truss floor system is borne by the beam. The first floor actually sits on the inside 4 inches because the block goes from 12 inches wide to 8 inches wide. Each subsequent floor is bolted to that bond beam.
“We bring block up to first-floor level and pour the bond beam and the vertical wall all at one time. Everywhere there is a vertical pour, we use a pour-through bond beam, a block that has a hole in it, then let it set up. The block doesn’t have to cure, so the crew can go on the next floor the next day. Once the load is transferred from the stick frame, which uses horizontal steel bracing, the block is supporting everything.”
One important difference between Bost’s masonry-framed house and many other concrete systems, where the concrete is poured all at once, is that all electrical box and plumbing decisions did not have to be made upfront. In this respect, Bost had the flexibility of construction on a standard stick-framed home. Many of the project’s special features were designed during the process of construction.
The biggest challenge in building this house, according to Bost, was a complex roof element involving dormers that didn’t align. The solution was to redesign the portion of the roof. Bost notes that it is common to experience some inconsistencies between the plans and reality with such a complex project.
Even with occasional challenges, the Tuscan Sun house may have broken speed records for a project of this size. The time from the first bulldozer pulling onto the job site to the opening of the home’s doors for a Parade of Homes viewing was slightly more than six months.
“We have big crews (15 to 20 men, including three or four master masons), even the interior trim crew was big,” Bost says. “While we were doing the exterior walls, the interior finishing was going on.”
“The response from the Parade of Homes was overwhelmingly positive. We estimated more than 13,000 visitors came through over three weekends. We won Gold in the top category for the third year in a row. Over the past 10 years, at least half of all my sales have come directly or indirectly from the Parade of Homes exposure. It has become our main mode of advertising our business. We do have a web site and get a lot of referrals from it, but it functions more as a brochure. If someone calls up and says they want to understand masonry framing, I can refer them to a number of articles.
For more information, visit bostcustomhomes.com.