Q We have a fourplex that in the winter gets mold growing in the bottom corners of the walls. This only happens in the corners of outside walls. There is no sign of water problems and this happens in all exterior corners of the building, even the second-floor bedroom. The building has plywood sheathing for siding, wallboard on the inside. It is approximately 35 years old and the walls have fiberglass bat insulation. One person thought the problem was due to electric heat and not enough air circulation. What do you think?
A It's probably not an indoor air circulation problem. Rather, it sounds as if the wind is intruding through gaps in the sheathing and corner framing. That will chill the corner, causing condensation and subsequent mold growth. In other words, it's a construction defect.
Standard framing at the time the building was constructed would have left a void between some of the studs framing the exterior corner, explained Phil Smith, energy specialist at the State Energy Information Office. In some cases, the framers would attempt to do the right thing by chinking the void with fiberglass, but this would not stop air leakage. Because sheathing joints over the corner framing would not have been sealed or treated to resist "wind wash" (air currents that reduce the effectiveness of insulation), cold outdoor air moves into the corners. Indoors, moisture clings to the cool surface of the corners, which supports mold growth.
To fix it, drill into the corner with a ¼-inch bit to get to the hollow space. Then, drill holes going up the corner every 6 to 9 inches. Use minimally expanding foam (the type intended for windows and doors) to fill the void, applying it at each interval and letting it cure before patching the holes.
Scratched stainless steel Q I have a stainless steel refrigerator that has some light scratches on it. I can't rub them out. Is there any way to remove them or repair the surface?
A With any appliance cleaning or repair questions, it's best to first look in the owner's manual for guidance, or contact the manufacturer by e-mail or phone. You can also ask at an appliance dealer that sells your brand of refrigerator.
Otherwise, try a stainless-steel cleaning product or polishing product. They're available at larger grocery stores and discount stores.
Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-9033, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit. Sorry, Fixit cannot supply individual replies.
