Questions from Client Regarding EMF Effects from Steel Siding
Question: "Are there any adverse health issues associated with steel siding?"
-- p.o., White Bear Lake, Minnesota
Answer: "Yes, there are several potential health issues associated with steel siding. It starts with the potential for electricity to flow on metal siding, whether steel or aluminum, from one point to another. Electricity flows on the grounding system of most homes, especially if they are supplied by metal water service supply pipes from city water. These have traditionally been connected to a metal city water main (unless the metal water main has been replaced with a plastic one).
"This allows return current to flow on these metal pipes from one house to another and back to the transformer. Like water flowing down a mountain, electricity is under such pressure (120 Volts) that it will take all available paths to get back to its source, the neighborhood transformer. If you give it parallel paths, such as the code-required bonding of the electrical panel to an underground metal water service supply pipe, electricity will go on that path along with the neutral conductor in the electrical drop service, which carries the bulk of the return current.
"That flow of electricity on the grounding conductor and other paths under the floor of your living space always creates a magnetic field, which is not cancelled by an equal and opposite flow of electricity in the opposite direction on some other conductor, such as you find in all wires in circuits and in AC power cords, where the hot and its corresponding neutral conductor are always side by side.
"This is the most common cause of correctable magnetic field exposure in a home. That current can run on many paths that are part of your grounding system: water pipes, gas lines (which are always metal, even if plastic coated), metal air ducts, and, in your case, metal siding. Remember that outdoor lights and outlets have metal boxes that are grounded and in contact with siding. I have measured current flowing on siding as it gets from one point to another. It is all about paths of least resistance. Electricity flows everywhere, like water down a mountain.
"This causes magnetic field exposure, which is a health risk and bothers my electro-magnetically sensitive clients. It is very difficult to isolate all metal electrical boxes from the metal siding, but if that can be successfully done, then it is not a problem from an EMF standpoint.
"There are more subtle reasons for not having metal roofing or siding, particularly aluminum siding. They prevent beneficial energies coming from outside from entering the home. Sounds woo woo, but it is mentioned in the 25 recommendations of Building Biology written decades ago in Germany, and I believe it.
"As with all siding, you want to have an air gap behind it to allow the rainwater that inevitably gets behind all siding, to drain down and out below the bottom to the ground. This air gap is over a drainage plane consisting of a weather resistive barrier. We recommend double D felt paper rather than plastic housewrap for that drainage plane.
"The ideal exterior siding from our standpoint is Hardiboard with an air gap behind it, or natural stucco, such as magnesium oxide or lime cement, without acrylic. Use Keim or one of the other mineral silicate paints as the top coat. These layers provide a finish that is 'waterproof but vapor permeable' to allow moisture that may get into the wall cavity to dry to the outside but prevents rainwater from entering. This makes the wall cavity fully 'breathable.'"
"You can learn more about this by reading our book, 'Breathing Walls,' available by clicking here."