Article No: 39

2006-05-01 08:11:16
Minnesota Masonry Builder Believes in Concrete Advantages

The mention of concrete block homes usually summons up a vision of white sand beaches and eternal Florida summers, but thanks in part to mason and general contractor Mark Olson, prospective home buyers could be shopping in the land of a thousand lakes where ice fishing is a major pastime for several months of the year.

A Mark Olson home. Photo courtesy of Dan Hatch

Olson, owner of Mark D. Olson Quality Construction in Minneapolis, Minn., has been building homes for more than 20 years and a masonry contractor for 16 or 17 years, making a living laying foundations and pouring floors and footings. About a year and half ago, he cut back on his subcontracting business and went into full-time general contracting of masonry homes.

"I built stick frame homes prior to that, but just on the side," Olson said. "For a period of time, I was so busy with the foundation business, I couldn't find the time. But in 1995, I built the first of the masonry homes for myself. I liked it so I thought about the possibility of doing it for others. In 1998, I had a client who wanted a masonry home built. In 2000, more clients came and I also put up a model. About that time, it became apparent there was a real demand for masonry homes. Now all I do is masonry homes."

One of the reasons people might not associate a northern climate with concrete block or any concrete material with a northern climate is the weather. Surprisingly, cold is not the worst enemy, rain is. A wet unit does not lay well. According to Olson, there is not much you can do with concrete block in the rain because too high a percentage of moisture can hinder the mechanics of the mortar itself.

"The moisture content of the block needs to be low so you have the capillary action that pulls the paste into block and creates an adherence. Rain is quite a culprit. This past year we have had a very rainy season with maybe two weeks of totally clear weather.

"The cold and freezing of winter weather is also a problem, but you still can come out with a really good product. It is easier to deal with than rain because you can tent and heat below 40 degrees. It is an expensive process, but is still doable. We have built buildings when the high temperature was at zero degrees."

Block Evolution

Olson is currently building houses with the Anchor Block Livingstone product. When he built his first house, there wasn't that option, so he spent time figuring out how he was going to keep his home from looking too much like a commercial building.

"I virtually had to come up with a system myself," Olson said. "Anchor liked what they saw when the house was finished and came up with the Livingstone system. Generally speaking, it is a split-faced block, which are two blocks made together and then split in two, giving it a rock-faced appearance. The system consists of a six- inch by four-inch by 16-inch block. There are configurations in that which allow us to do some things we were not able to do before. Every sixth block has a solid end. A tool on the job allows us to make a kind of 'L corner.' You can use different lengths and any degree miters you want. When you use it on the corner, the next cell on the block can be core filled, providing a structural integrity that was harder to achieve before.

"With a company called Cemstone, I developed a product that would be a core filled mixture that achieves a 3,000 psi in a number of days. The difficulty we had prior to developing this product was getting core fills with concrete and # 5 rebar rods to consolidate. It actually runs around all corners, filling any nooks and crannies in the wall because it is almost as runny as water and still achieves the 3,000 psi strength.

"The block in this system is an offshoot of an architectural unit used for many years. What makes it different is that it goes into a six-inch block instead of the conventional eight-inch or 12-inch block generally used in commercial work. One advantage is that it saves space; another is that twice as many six-inch blocks can be manufactured than others because of the way the mold is made. It sounds a little like splitting hairs because it doesn't save a lot of room, but even 3 1/2 square feet in the right place can be quite a bit. A third advantage and maybe the main one is that it is cheaper to make the six -inch block and the savings are passed on to us."

Olson said that he does not insulate the interior of the concrete blocks he uses, because in Minnesota it hasn't proven to be efficient enough. There is still a lot of heat transfer through cell walls.

"What we do use is a polyisocyanurate or polyiso," Olson said. "The insulation has a foil face on both sides. Because of heating degree hours here, it doesn't make any difference in insulation whether you put it on the inside or the outside. It is, however, more cost effective to put it on the inside. We apply it right to the block and put up a 1 5/8-inch metal stud. That gives you an 18.3 R value, and with 1 1/2-inch space, you get another R 3. There also are a number of efficiencies because of the thermal mass. Because the polyiso is a 4-foot by 9-foot sheet placed on the wall, you also have a continuous vapor barrier.

In some ways, masonry block construction actually simplifies the installation of the plumbing and electrical wiring. Olson indicated that there was little difference from wood frame because he uses wood floor trusses. In exterior walls, subcontractors only needed to use different fasteners. In general, it is almost easier for an experienced electrician to put the wiring in a masonry block home because, unlike wood studs, metal studs don't require drilling.

Hands On

There is quite a selection of architectural style blocks, surface finishes and colors for the prospective home builder to chose from, plus blocks specifically designed for acoustical or energy efficiency. Many of these require slightly different masonry skills.

"Every style of block has its tricks," Olson said. "There is a learning curve, whether it's a smooth-faced block, rock-faced block or scored or fluted block, for example, because the characteristics you are trying to bring out in each block vary. If you use a smooth-faced block, and don't lay them straight, there will be a lot of shadows. If you use a scored block and bed joints aren't flat, it really shows up. Rock-faced blocks are generally a little easier to use, but still must be done well because if your mud sticks to the face, clean up will be difficult."

Olson noted that it could be difficult to put together a crew of experienced masons, depending on the time of year. As you might expect, during the winter quite a few masons are available, but during the heavy building months, it is tougher to find them. Also, you have to pay a premium wage for that person.

"It would be nice if we had a formal apprenticeship program in the Twin Cities," Olson said, "but we don't. And all the builders are so busy, they wind up teaching their own people, naturally, in the way they want them to lay block. I need to train my people too. I generally start them off as laborers, so they understand how to mix mud and where things go and the general process prior to laying the blocks. Then, in time, I put them on the line. Usually, they learn how to use the trowel first, then spreading mud and the techniques of that, until the trowel actually becomes part of their hand. It is amazing to watch a good mason work. Next, they learn how to lay block straight and square. Finally, they learn to build leads, using a level, getting heights right and walls plumb and true, and keeping blocks level at the corners. About 25 years ago, I learned to be a mason with just that process."

Looking Ahead

There is currently a lot of interest at the National Concrete Masonry Association in getting below grade masonry contractors to move on up; in part, because the necessary skills are in place.

"I built foundations all those years and then I took the same crew and started building houses," Olson said. "Still, there continues to be a high demand for foundation masonry here in Minnesota, so the time element is the problem. In a basement, there is a time schedule of one to three days. In a masonry house, it is more like two to three weeks. It is hard to mix the two back and forth. The developer approach, where crews move from one lot to the next, would be a solution.

"It is a good time to move to masonry-built homes. The problems in stick-built homes related to mold are big. I'm not saying masonry is impervious to mold, but the way we are building our walls makes us much less susceptible to the mold, mildew and rot problems. The people we are selling to are looking for the last house they will have to build. They are tired of siding that gets blown away and hail-damaged. I just tore down a stick-built house that was only 27 years old and had literally rotted away; and am now building a concrete block house in its place. Generally, my clients are not starter-home people. They want a home that is built right — one where they don't have to put $40,000 of their equity back into the house just to maintain it in 10 years."

Olson has found people are not really familiar with the many systems out there. The biggest marketing tool for him has been being in the Parade of Homes and putting up models. And like many builders, he has a Web site:

"It takes a major push in the press to get people to get out to see these houses," Olson added. "People have to have a reason to change." Masonry block homes offer one.