Stretching & Stripes

Donald E. Smith, CCS

September 2005

We have been experiencing a more than usual rate of muscle strains and related injuries. They are not time loss injuries, just annoying and cause a loss of production. Any suggestions on how we can resolve the situation?

This is a topic that was discussed during the Safety Directors Forum at AWCI’s annual conventionlast spring. Erik Haruch, safety director for McNulty Bros. in Chicago, experienced the same problem. Recalling his high school days of playing sports, he remembers always warming up before starting practice and before a game. It made Erik start thinking.

He recalled watching his workers coming to the job, sitting around with a cup of coffee, and then starting right in on the task at hand. He realized, especially in the winter, that most of the workers were stiff from the cold. Erik devised a set of stretching exercises to enable his workers to loosen up before hoisting sheets of drywall and buckets of mud and for that matter, taping and blocking drywall panels.

Erik wasn’t thinking about a full workout, just enough to loosen up stiff joints. The program was successful in that it reduced strains from stiff muscles, but it just wasn’t popular with the workers. This was especially true when his crews were doing the workout in front of workers from other companies on the job site. So Erik and his boss approached the local unions and the general contractors they worked with on a regular basis and explained what they were attempting to accomplish by the warm-up drills. With documented results of injury reduction in hand, they were able to convenience the unions and contractors that this was a viable program. Seeing the advantages along with the documentation, the unions and contractors adopted the warm-up program. Remember: Even if you are playing a friendly game of golf, you take at least a few warm-up swings before you tee off.

I have a question about a ranch-style house I recently worked on. When I entered the home I noticed the interior of all the exterior walls had black stripes on the wallboard coinciding with the exact location of the metal joists. These stripes were on the inside of every exterior wall in the house as well as the ceiling. The homeowner said she had painted the walls but the stripes eventually came back. I have never seen this condition. I hope you may be able to explain how it happened and possibly offer a solution.

What you saw is thermal bridging caused by condensation forming on the steel framing. The black substance may or may not be mold. Due to the thermal difference on the surface of the drywall, the condition exists for hydrocarbons to be attracted and trapped on the surface. The fix would be to insert a thermal break between the drywall and the steel framing. This is not an easy job, nor is it cheap. An insulation contractor may be able to install spray insulation into the cavity to achieve the required thermal break. The expensive solution would be to replace the drywall and install a thermal break on the framing. Starting in the early 1990s the thermal bridging question in light gauge steel was researched and addressed. A publication called Thermal Design of Cold-Formed Steel Exterior Walls is available online; it provides suggested insulation levels and wall system descriptions. In addition, the International Energy Conservation Code 2003 edition has a chapter describing the prescriptive requirements for single-family homes, and Table 602.1.1.2 in that chapter has the values for steel-frame walls.

A cosmetic fix would be to determine if it is mold or dirt on the wall’s surface. Once the substance has been identified, clean the wall surface to remove the substance and prepare the cleaned surface to receive a finish coat of paint. Bear in the mind that the cosmetic fix will not last forever, and the process will have to be repeated in five to eight years.

I want to thank Don Allen of the Steel Framing Alliance for his input on this subject.
About the Author
Donald E. Smith, CCS, is AWCI’s director of technical services. Send your questions to him at smith@awci.org.