THE BUILDING ENVELOPE
- By Jerry Enderle
- October 1st, 2003
Because of technical advances in materials and construction details, the building envelope has gone through significant changes. In buildings built during the 1920s and 1930s, you will find stucco at least one in. thick, brick walls 12 in. thick and stone never less than four in. thick. Today, in some areas, exterior school walls are made with synthetic stucco that may be as little as one-eighth of an inch thick, or curtain walls made of glass or even poured concrete. In some cases, the components of the structures are built off site and shipped in. What factors do decision makers look at when determining a building’s envelope? SP&M talked to members of Turner Construction’s team, located in New Jersey, the Chicago area and Sacramento, Calif., to find out. Here is what they had to say.
Terry Fielden, operations manager for Turner Construction’s Chicago office, says there really isn’t a lot of variance in materials in his region.That’s partially because this market seems to like the status quo. They don’t want to try things that are new. Districts don’t want their school buildings to be the guinea pigs, he says. One problem this can create, Fielden says, is that material costs may fluctuate, depending on the saturation of the market.
The thing is, with the cold climate in New Jersey and in Chicago, for example, the materials make a big difference in the longevity of the building. It’s impractical to use any kind of a stucco or Isis in these colder climates. They won’t last, Fielden says.You can, however, use them under canopies and some exterior soffit work, but usually you try to keep them protected from direct exposure to the weather, he adds.
All of the team agreed that the climatic conditions of the geographical region in which a facility is being built has the greatest bearing on what materials should be used. There are always people in the marketplace trying to do new things and investigate new things. We are not adverse to that at all, but you need to test any new material to make sure that it really the best thing you want to use — that it holds up through time, explains Doug Diercksen, manager of education in Turner’s New Jersey office.
For example, adds Fielden, in the ‘50s, they built a lot of public schools in the Chicago area with exterior curtainwalls and aluminum wall systems. They didn’t stand the test of time like some the masonry walls in some other Chicago buildings. Some of the 100-year-old schools are in better shape than some of the 30-year-old buildings that were built with the curtainwall systems.
New Jersey has a dual track in terms of the school market, says Diercksen. One track is driven by the School Construction Corporation, which is a state agency, and one is being driven by a K-12 suburban school marketplace. So the decisions are being made from a ‘green building’ approach, he says. That is typical of a large agency that is looking for efficiency and cost savings — a better way to build a mousetrap.
Ken Harms, director of education facilities for Turner’s Sacramento, Calif., office, says that in California, most schools are funded by the state. So decision makers look to the Division of State Architects or the funding source for a lot of their guidelines, he explains. School construction out here mainly consists of wood, stick-built or brick veneer. Once in a while, there are projects that are locally funded and are a bit different. We are currently working on a $6-million high school structure using steel, but most of the time it is wood frame. You do not see a lot of unique materials that are being explored.
Although modular construction is making its way into the school market, it hasn’t been predominant in New Jersey and Chicago. We haven’t seen a lot of modular construction here, says Mark Iammarino, vice president and director of education for Turner’s Chicago office. Typically, if we see the
modular construction, we see precast concrete, and it is used when building structures such as gymnasiums.
Harms says that in California modular building has been part of school construction for decades because the state requires a certain percentage of construction be modular. Usually, he says, these are in the form of portables.
Roofing systems seems to be pretty standard, as well, in the three areas. Again, all agreed that materials used on roofs are chosen according to climate. In New Jersey, many structures have flat roofs and use a rubber sheeting material to avoid water leakage, condensation, structural failure, mold and mildew contamination. In Chicago, many structures are built with sloped roofs, using metal or shingle coverings to contend with snow and ice. In California, Harms says that the sloped roofs are used more often in the higher altitudes for the same reason.
One thing that seemed to be common in all areas was the idea that most schools are still being built using block interior walls. One reason is its durability in high-usage buildings, but another has to do with mold. There was consensus that placing drywall on exterior walls presents a potential problem with moisture and mold because of condensation and possible water leakage. Diercksen says he doesn’t recommend drywall even for interior partitions in New Jersey because it is hard to control moisture, both during and after construction.
Harms syas it’s a matter of risk management. There are a lot of places where chalkboards or lockers cover entire walls, and you have to ask, is it worth putting the school district at risk for future mold cases. It’s not worth saving a penny or two there. The problem is, you can’t necessarily control moisture.
In addition, Harms says, after studying costs, he has found that a six-in. block wall runs about the same cost as a
So, what it comes down to — the building envelope affects a school's environmental performance, and the composition of building materials affect indoor environmental quality and long-term budgetary issues, such as energy use. Therefore, by focusing on the building envelope's geometry, orientation and material composition, you can achieve the ultimate goal, which is to ensure the health and safety of building occupants and to protect them from the elements.