Q. The interior of my microwave has ice droplets in it right now because of the below-zero temperatures in northern Illinois. I've included a photo. The stove hood (below the microwave) is vented to the exterior of the home. Does the ice pose a danger to the microwave?
Right now I'm keeping the door open, as well as the cabinets above it. (There is an opening in the cabinet above so that the power plugs into an outlet inside the cabinet. It's always cold in there in the wintertime.) This has never happened before and I've been here for 10 winters. Of course, we've not had -15 degree temperatures as we have had lately, either. Thanks so much.
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A. The photo does not show the stove hood. Is it directly in back of the stove's console or ducted inside the wall and outing behind the microwave?
It is not normal to have icicles inside a microwave oven; there is a source of cold intrusion or a lack of insulation in the wall, which would explain why the insides of the wall cabinets are cold.
Without more details and information, I can't offer an intelligent solution. You may want to consider having a specialist in energy audits survey the situation with the instruments he or she has to see what is going on in that area.
If there is an insulation problem, there are several approaches, depending on what is found. They are:
• Blow cellulose in the walls, if there is space.
• Take the cabinets and microwave down, move the stove, add 1-inch thick rigid insulation over the existing wall finish and then cover it with new gypsum board. Reinstall the cabinets and microwave with longer fasteners.
• If the siding is vinyl, consider adding rigid insulation behind it.
Q. We live in the Chicago suburbs and are planning to finish our basement. I read your column in our local paper every week and I know this subject was in one of them but don't recall the details of your answer. The foundation wall is poured concrete, and the outside grade is a foot or so down from the foundation. What is the proper way to insulate and frame the basement walls? We were planning on using two-by-four studs on the perimeter walls. Are there any other considerations?
A. In cold climates, there is always the risk of deep frost penetration that can crack even poured concrete foundations unless several factors are in place:
• A well-built foundation drain system has been installed, consisting of a drainpipe next to the footing, a deep stone bed around and over the pipe, and covered with geotextile fabric.
• The remaining backfill consists of coarse sand or bank-run material to within one foot of the final grade.
• The backfill should be completed with native soil to grow grass; it should be sloped at the rate of 2 inches per horizontal foot for a few feet.
• Avoid flower beds and other plantings next to the foundation; keep them a few feet down slope.
• Make sure you either have gutters and downspouts that discharge water on splash blocks or extension pipes and away from the foundation. If you have none, embed flagstones or concrete pavers flush with the grade at the roof's drip line.
To insulate the poured concrete foundation walls from inside, adhere 1-inch-thick XPS (extruded polystyrene) rigid insulation with Styrobond or polyurethane caulking to clean walls and build the 2-inch-by-4-inch walls against the foam. Be sure to use a pressure-treated base plate. The framing can be 16 inches or 24 inches on center. Fill the framing with fiberglass and cover it with whichever is your choice of finish material. If you choose 24-inch on-center framing, and decide on drywall, you should use ⅝-inch-thick gypsum board.
Q. Our house was built in 1989 in Essex, Vt., and was well-insulated at that time -- it is two-by-four construction with 2 inches of rigid polystyrene on the outside. Our windows are Marvin low-E argon filled. In 2009, we had a home energy audit done and had our home sealed and extra insulation put in the attic. We also replaced our old propane boiler with a more efficient Buderus hot water boiler.
Our house is now very well sealed, requiring us to automatically run a fan to ensure our home receives the proper air exchange. We also have installed automatic thermostats that turn the heat down at night, but Buderus recommends we only adjust it by a couple degrees to allow for proper boiler operation.
We use a hygrometer to measure the humidity in the house and in the winter keep it around 35 percent with the temperature at 66 to 68 degrees -- it is never higher than 40 percent. We do not humidify the air; this air humidity is accomplished with plants and normal living. This level of humidity is within the recommended winter range for comfort and to avoid dry skin and nasal passages (our family is sensitive to both conditions -- so significantly lower humidity is uncomfortable).
Our problem is condensation on the interior of our windows on cold winter nights. On really cold nights, we even get ice buildup in the lower corners. Our interior window frames are wood, so this condensation is ruining the paint and we even get slight mold in the corners of north-facing windows. We have stopped closing our pleated window shades (sealed at the top and weighted at the bottom) on winter nights, hoping the elimination of trapped warm air between the quilt and the window would decrease the condensation. It helped some, but we certainly still get the water and ice buildup on cold nights. Some days we wipe up water several times during the day as the ice melts, and on really cold days and nights, the ice on the windows never completely melts. We do not have condensation problems anywhere else in the house -- just the windows.
We plan to repaint our interior window trim this spring and would like to know if you have any suggestions on the best method and best materials. What is the best primer? Could/should we use exterior paint since it would be more water resistant? How about a topcoat that is water impermeable -- is there such a thing? Can you suggest a product?
A. Lowering insulating shades on cold nights will result in condensation on most windows because, as you correctly identified, the trapped air is cooled through the glass and the dew point is reached.
You mention running a fan to obtain needed air exchanges; this may not be sufficient in your case. You may want to look into an air-to-air heat exchanger.
Buderus' recommendations are based on its desire for optimum efficiency, but lowering the thermostat by 6 to 8 degrees for the night is what is recommended to save energy. However, doing so will increase the condensation on your windows, as cooler air cannot hold as much moisture as warmer air.
In Vermont weather, even the best windows may suffer from condensation and some icing. The answer, short of lowering the interior relative humidity (RH) -- which, as you say, is at a healthy level in your house -- is to install storm windows. You haven't mentioned what type of windows you have: double-hung or casements. You may want to investigate the possibility of having storm windows installed that will not impede the use of the primary windows, but if this is not feasible, an alternative is Magnetite windows, which can be removed in the spring.
With storm windows, you should not need to repaint your windows. The paint you use must be compatible with the factory finish on your windows.
Suggestion from an Illinois reader: I read one of your recent columns in the Daily Herald and would like to offer the following suggestion:
Many years ago, I had a problem with yellow jackets finding their way into the exterior walls of my house. At that time, I had a friend who was an entomologist with the University of Illinois and he told me to do the following:
"Locate the entrance and exit holes that the yellow jackets are using. After dusk, when they are less active, take some very coarse steel wool, sprinkle it with Sevin Dust, and then loosely pack it in the holes. The insects will try to pick away at the steel wool to gain exit and get the dust on them, then carry it back to the nest and it will destroy all the others. It may take several applications, but it has worked dozens of time for me and my neighbors any time we have a problem like this.
A. This should be effective for the carpenter bees as well. Just make sure you use gloves and a dust mask when applying the Sevin and handling the dusted steel wool.
Clarification from an Illinois reader: In a column of yours that appeared in our local paper in late January, a reader had a question about black garage doors. You advised he could paint new steel doors and recommended a paint formulated for metal. For garage doors, that is wrong. Almost all paints for metal are oil-based and not compatible with the factory finish. The factory paint will fail and peel. The recommended paint is acrylic latex made for exterior use.
My authority for what I say? For 57 years I have owned and operated a garage-door dealership.
A. Thank you for that correction.
• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at firstname.lastname@example.org.
© 2014, United Feature Syndicate Inc.