Moisture problem may be related to inadequate insulation
Q. I have been having a problem with my interior walls. It only happens when the weather gets extremely cold (10 to 20 degrees). A corner of my bedroom ceiling gets mildew on it, and I can see drops of water sort of hanging from that area. My walls seem cold and almost damp to the touch (there is no running water that is coming down the walls). Behind furniture or inside closets where clothes are crowded, mildew will appear. I treat it with Clorox and a sun lamp, which does the trick. But it continually comes back in very cold weather. I laid more insulation in the attic 10 to 15 years ago.
The house is approximately 60 years old, and my husband built it. Do you think blown-in insulation would help me? I have forced-air oil heat, and we keep the temperature at 68 degrees. There is a valley directly across from my home from which we do get some very strong winds. We have a wood-burner in our downstairs game room that helps with the heating of the home. My husband insists it's because the inside temperature isn't high enough to keep the walls warm.
A. A house built in the 1950s may not have adequate insulation in the walls and the attic, or the insulation may not be installed properly. It was common at that time to use 2-inch fiberglass insulation ("masonry insulation") or an accordion-type Kraft paper that had several layers with narrow air spaces between them. Neither was very effective. And if the attic insulation does not cover the entire wall plates, there is a void resulting in considerable heat loss. These two possibilities would account for the ceiling and wall dampness. Corners are most vulnerable because they have two weather exposures.
Mildew will grow in closets and behind furniture because there is poor air circulation and the walls are colder. If the added insulation you put in the attic does not cover the entire wall plate or if there are voids between the bottom of the insulation and the ceiling below, cold air will keep these areas colder than those farther in the rooms, and condensation and mildew will form.
It was customary at that time to use Kraft-paper-backed fiberglass insulation and to staple the flanges to the sides of the framing, which leaves triangular tunnels on each side of the batts through which cold air can flow, cooling the finish surfaces and leading to condensation.
If the walls have only 2-inch thick fiberglass or the accordion-type Kraft paper, it may be possible to have dense-pack cellulose blown in the walls to improve their performance. By using a wood stove, you are reducing the need for the furnace to come on, and this keeps the other rooms cooler, encouraging condensation and mildew.
Your husband is right; my guess is that you used to keep your house warmer before the energy crisis and high fuel costs. And, more than likely, you didn't have a wood stove skewing the heating system either. Contact a certified energy contractor through one of your utility providers to investigate and offer solutions.
Strong winds affect the performance of any house not built to resist them. A 60-plus year old house is not built to new standards of energy efficiency. Adding blown-in cellulose insulation in the attic is probably worthwhile, as long as it is done to take care of any existing deficiencies at the wall plates.
Q. We have a very perplexing problem. Our house is around 25 years old. The house is northwest-facing and is part way up a hill, so there is ledge that rises up behind the house. We're having a problem with the venting of septic gases, which has been getting worse over the past several years. When the temperature goes below 0 degrees, the septic gas backs up into one of our two upstairs bathrooms and renders the attached bedroom unusable. The exit pipe on the roof, which I think is around 3 inches, actually gets closed off with an ice blockage.
We have tried different exit-pipe lengths and angles all with no change in the problem. I also went into the attic crawl space and put insulation around the pipe wherever it was exposed. We had plumbers in, but they didn't have a solution outside of suggesting tearing out the walls to check the pipe. I had a roofer go up and install a roof-heating wire around the pipe and have it plugged in all the time. He also put a cap with side vents on the pipe. So far the pipe is open, but we haven't had a return to subzero temperatures yet. Do you have any ideas?
A. A vent pipe carries a lot of moisture since it vents all the plumbing in the house, and there is a lot of hot water usage that increases the moisture within the pipes. In cold climates, any vent pipe that is less than 4 inches in diameter and goes through a cold attic space and over the roof is likely to frost up and become sealed. But I don't think this is your problem. My guess is that the offensive sewer odor coming out of one bathroom upstairs is caused by a deteriorating toilet wax seal. When it gets very cold, the stack effect in the house increases and makeup air is drawn through the base of the toilet. In this case, replacing the wax seal with the newer waxless seal should take care of the problem for good.
Q. It seems unlikely that my more than 20-year-old A.O. Smith hot water heater will survive much longer, and I'm looking into possibilities for a replacement. I've read much about tankless water heaters; in particular, how energy-saving they are. But I've heard from former users that they're inconvenient in practice because hot water is not immediately available. I would very much appreciate your opinion and your feelings about the best ones to buy.
A. Tankless water heaters are very efficient in saving energy, but they do have some drawbacks. There is a long wait to get hot water if the heater is far from all fixtures, but the same goes for regular water heaters unless there is a return line and a circulator that keeps hot water running to all fixtures at all times. A special pump that will accomplish the same thing can be installed in homes as a retrofit. It is possible to have a similar retrofit pump installed with a tankless water heater, but it defeats the purpose, since it will require the heater to come on even though you are not using hot water in order to have instant hot water at all faucets.
Another consideration is your family's lifestyle. If several people are showering at the same time, or the dishwasher or clothes washer are used at the same time as one is showering, you will need to install a large enough unit to accommodate these needs. Add all of these against the costs in order to make the right decision for your particular situation.
Q. I had my cement-block, two-flue chimney rebuilt three years ago. The chimney goes up through the center of the house. There is flashing around the entire base of the chimney. I am finding a seepage of water following major rains or snow melts around the chimney. I can see the outline of the concrete blocks due to staining from some of the seepage near the ceiling on the chimney. Is there a recommended sealant to use on the sides and top of the chimney that I could apply to deal with this problem? Also, the interior chimney is painted with an off-white, stucco paint that will need to be repainted. What product would you recommend to cover the stains?
A. The leakage could be caused by an inadequate flashing job. On a shingled roof, step flashing must be installed under each course of shingles with each vertical leg against the chimney masonry. All step flashing must be covered with counter flashing embedded in the masonry joints. If the roof pitch is very shallow and covered with roll roofing, the roll roofing should have been lifted to allow for a membrane to be installed underneath. Then the roll roofing is set onto the membrane with plastic roofing cement. The membrane should go up the masonry walls by at least 5 inches and be covered with counter flashing. This is the only way to ensure that the joint between the chimney and the roof is waterproof.
Although heavy rain can cause leakage through the masonry itself, the fact that it also occurs when snow is melting would more often than not indicate a flashing problem. Since concrete or cinder blocks are quite porous, wisdom would dictate that they be coated with stucco and a sealant. Melting snow should not cause such leakage unless the snow is deeper than the counter flashing is high, which would be very unusual. In that event, the heat from the chimney would melt the snow away from the masonry, without causing leakage.
The chimney cap should also be checked for cracks or other shortcomings. You may want to have another mason check to see if the work was done properly. To cover the interior stains, paint the affected areas with B-I-N, followed by your choice of finish coating.
Q. We have a two-story family room with two, six-foot openings into the second-floor hallway. With Chicago winters, the heat in the family room rises and floats into the upstairs hallway. We have always closed off the two six-foot openings to make our family room much warmer. However, our furnace service company told us not to block off the two openings but instead to cover the cold-air returns in the four vacant upstairs bedrooms. Is this the ideal? Should we close the bedroom doors also?
A. Even with the two openings closed off, your warm-air system is still sending warm air into the bedrooms and returning cold air to the furnace through the ductwork. You can partially close the dampers on the bedroom registers and close the bedroom doors in order to maintain a modicum of heat in these rooms and still seal the two six-foot openings.
• 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 e-mail at henridemarne@gmavt.net.
© 2009, United Feature Syndicate Inc.