Article No: 76

2006-05-01 14:10:01
Spanish Colonial Ambiance
By: Carole McMichael

George A. Pontikes Jr. and his wife Laura wanted a house that would suit their active family lifestyle, including casual entertaining. At the same time, they wanted the old world solidity and ambiance that comes with thick concrete walls.

If you are traveling through the Tanglewood area of Houston, you will come upon the Pontikes' home — a 6,800-plus square-foot, Spanish colonial with a stucco exterior, travertine slab doors and window sills, reclaimed clay tile roofing and an 18th-century antique front door. Inside, you will find knotty pine and Spanish saltio tile flooring, custom iron light fixtures, hand-painted tiles and ceiling details, iron handrails and balusters, and distressed wood millwork with a hand waxed finish. This house fits in comfortably beside its neighbors, but one thing makes it quite different — it was not stick-built.

Photo by Newberry Campa Design Sudio

When deciding on a building method for this home, Pontikes, CEO of Satterfield & Pontikes Construction Inc., went with years of experience in commercial building and chose concrete masonry units (CMU) and hollowcore planks.

Stage one — planning
According to architectural designer Troy Campa, partner in Newberry Campa Design Studio LLC, he hadn't worked with concrete before, so he did a lot of research upfront. "Pontikes didn't come with finished plans," Campa said, "but stressed that he wanted to use CMUs and hollowcore because they were a stronger and longer lasting building material and his construction crews were familiar with the building method.

"There were no direct adaptations to the plans to accommodate using CMUs because we knew from the beginning we were going to be using concrete. One thing that was a little different than designing for typical stick-frame was the hollowcore plank flooring, which has very specific limitations on where you can cut holes and how large the holes can be. It made it a challenge to locate plumbing and HVAC.

"The dimension of the blocks was something we had to be aware of, but it was not a problem. We were very careful where we put windows and doors because of the placement of the concrete beams. We also had to take into consideration the load we were applying above them. For this, we worked closely with the structural engineer because it was our first concrete house. Overall, openings in the CMU walls were not as much an issue as the openings in the plank flooring."

Campa noted that with stick framing, the architect can plan the placement of the plumbing and electrical lines pretty much as he wants to, but in the Pontikes' house, the client, concerned about weakening the strength of the walls, didn't want utility lines cut into the CMUs. Consequently, the plans included mostly furring out a few extra inches. This worked perfectly because it created thicker walls, which fit in with the Spanish colonial style.

"Compared to designing for stick-built," Campa said, "designing for a concrete house would take about the same time. This house took longer upfront to research materials and limitations only because it was our first with CMUs. In general, with concrete, it is difficult to make changes after the fact, so you have to make sure before you start construction that that is the plan you are going with. This must be understood between client and architect. The Pontikes were very clear on that and stuck to it. Changes to finishes on the interior would not be a problem, so they continued to evolve."

There were two unusual design features in the Pontikes' house. First was the use of multiple half-levels, which Campa noted is becoming popular with his clients, especially having the master suite at a different level than the children's bedrooms. The rooms are separated, giving the parents more privacy, but the children are still close by, rather than on the opposite end of the house. Second was a sub-basement that is a half level down into the ground where Pontikes, a wine collector, wanted a wine cellar, which true to the Spanish colonial ambiance, would be below ground.

Stage two — construction
The foundation was constructed of piers and beams. The first and second floors were constructed of Gatecore hollowcore planks, which were 4 feet wide and ranged in size from 5 to 23 feet in length. The exterior walls were constructed of 8-inch CMUs with steel reinforcing and expandable insulation.

One of the reasons Pontikes decided to go with this type of foundation and floor system is the expansive clay (black gumbo) soil on the building site. Expansive soil tends to push up against the concrete and crack the slab or get it out of level. There aren't a lot of choices in how to deal with it. The builder can dig out the soil and replace it or create a void area below the concrete slab using cardboard void boxes. After the boxes deteriorate, they leave room for the expansion of the soil without heaving the slab.

Pontikes and his contractor/partner, Jim Brown, decided to kill two birds with one stone by getting the underground effect for the wine cellar while solving the soil expansion problem. They created a void between the slab and dirt. This raised the first floor, leaving a 2-foot crawl space. By raising the first floor, it reduced the depth needed — only 6 feet into the ground — to create the cellar.

"For the pier and beam foundation made of reinforced steel and poured concrete, we drilled bell footings," Brown said, "to an average depth of 14 feet below grade. We leveled the dirt and treated it for termites and insects. Then we laid courses of smooth CMUs around the house, which left us 2 feet above existing grade.

"Next, we laid the hollowcore planks on top of the masonry wall and pieced them together using the tongue-and-groove joints. On top of that, we added steel reinforcement and poured high-strength concrete, which left a smooth, level floor slab. The planks are custom designed to fit the floor dimensions. We had to get the shop drawings done and then schedule when the planks would arrive. Everything had to be completed up to that point, so when the planks came, you could just drop them in place. Then, we ran the CMUs up to the second floor height and laid another plank floor. The second floor was topped with concrete like the first, and the perimeter CMU walls were brought up to a finished elevation at the roof line."

All cavities in CMUs that needed more support were filled with grout. The grout filling was done between courses. Areas that were not filled with grout, such as that below the windows, were filled with high-density expandable foam. They drilled holes in the inside face of the block and using a little tube, pumped foam into the cavity under pressure. Because the foam is under pressure, it will seek every empty place. The drill holes are filled in with mortar afterward. It is easier to do the filling from the inside because the crew does not have to use ladders or scaffolding. Foam also adds insulation.

Besides, or in addition to, filling CMU voids with foam, builders can attach rigid insulation on the interior side to achieve energy-efficient R-value. Brown used the rigid insulation in some areas depending on how the wall would be finished; for example, the wine cellar, which has poured concrete walls, required very dense foil-faced insulation and was sealed with a special tape at the joints.

The majority of downstairs walls are concrete, but in the upper bedrooms, interior walls are wood-frame, covered by sheet rock. Brown used structural wood trusses and insulated wood plank panels for the ceiling of the living room, and wood framing with supplemental steel beams for the remainder of the roof.

Extra details
The scheduling: In scheduling, the timing of getting the walls up was not really the issue, as much as delivery timing of the planks. The panels also brought up a logistics problem. The client's lot was in an old, established subdivision. The big plank trucks had to be especially careful of the neighboring property and the huge oaks on the client's site. They backed up the driveway because there was not much room to maneuver on the street. Once the truck dropped a trailer of planks, a big crane located by the side of the house set the planks. Placement went quickly, according to Brown, in a day or less than a day.

The personnel: Although some of the other concrete building methods are new enough to create a lag in experience among crews, subcontractors and code inspectors, this is not the case with CMUs and hollowcore construction, which has been a standard building method for commercial projects for some time. Pontikes' own company handled all the concrete work, but subcontracted all other work out, including the masonry.

The weather: Obviously, cold weather is not a problem for CMU construction in the Houston area, but builders do have to deal with a lot of rain, which is not good for working in concrete. Brown deals with the wet conditions by using covering when possible and relying on the short drying cycle. Actually, the drying cycle can be too short in the summertime, when it can get too hot; so ice and other admixtures are added into the concrete mix to slow down the drying process.

The HVAC: For air conditioning, the client went with a commercial chill-water system typically used in hospitals or schools. It is not a split system. From the chiller outside, cold water runs through the pipes to cool much like an AC system forces cold air through ducts.

Concrete is a more flexible medium than it seems like," Campa said. "I was afraid I was going to be a lot more restricted than I was. More important, I never felt the material was preventing me from producing a better design.

"I love it [CMU construction]; I really love it. One of the reasons is that once you get started, it is a very quick form of construction. And I enjoy the inherent thickness of the walls — specifically for this style of house. If I thought clients were open to alternative methods and interested in this style, I would definitely steer them toward concrete."