Give Mildew Problem a Breath of Fresh Air
QUESTION: Our 16-year-old painted redwood house has a terrible mildew problem, even during periods of bright sunshine. The inside of the house seems to sweat and the inside surfaces of the window frames are peeling. We would eventually like to have aluminum siding, but first we must solve the mildew problem. What do you suggest?
ANSWER: You have probably checked the obvious sources of moisture such as a lack of kitchen and bath fans, and poor exterior landscaping that may allow rainwater to run into your basement and crawl space. Moisture rising from these areas is a common source of this problem.
If you do not know the source of excessive moisture in the house, you should introduce some dry air from the outside. There are a number of air exchangers on the market that are designed for do-it-yourself installation and are reasonably priced. These units usually have a fan that moves fresh air in, over or through ducts that are heated by heated air from the interior of the house moving out through the same unit.
This is not only a solution for excess interior moisture but an answer to super tight homes that suffer a lack of fresh breathing air.
Insulation, Vapor Bar Needed for Metal Roof
Q: I own a fine old home built about 1925, with a cypress shingle roof installed on 1-by-4-inch wood strips, 8 inches on center. The attic has no ventilation or insulation. I would like to install a painted sheet-metal roof over the wood strips. My concern is condensation on the bottom of the sheet metal. What is the best way to do this?
A: Providing ventilation and a vapor barrier in the attic will control the moisture buildup and resulting attic condensation. You should also insulate the attic. Even though your house is located in a warm climate, insulation is cost-effective and will help make the house more comfortable.
During the summer, it’s possible for the attic temperature to reach as high as 150 degrees F. Attic insulation and ventilation helps reduce the heat load on the ceilings of the rooms below. It also helps reduce air conditioning costs.
Check with your local utility company to determine the recommended amount of insulation for your attic. It is more practical to install insulation batts with an attached vapor barrier. Place the batts on the attic floor between the joists with the vapor barrier facing toward the rooms below.
You should also use at least two vent openings to allow for air movement. Installing watertight vents in the sheet-metal roof may be difficult, so your best bet would probably be to use gable vents. A combination of gable and soffit vents would be even more effective.
Since there will be a vapor barrier in the attic, the size of the vent openings can be less than would be necessary without a vapor barrier. Remember, the vent’s effective area is less than its actual opening. Screens or louvers can reduce air flow through a vent by as much as 50%. The effective area should be at least 1/300th of the attic floor area.
Smoking Stove May Need More Chimney
Q: Our new wood stove smokes up the room when we open the stove door for stoking. We have a trilevel house, and the stove uses six feet of pipe from the stove to the ceiling, then another six feet of pipe through the roof topped with a rain cap. The salesman who sold us the stove said we needed another two feet of chimney for sufficient draft to stop the problem. We did this but the problem persists.
A: There are several angles to consider when the draft does not appear adequate. Most wood stoves have recommended drafts. You can check this with a manometer that should register .05 inches of water when placed in the flue. The location of the stove in the house is also important. If the stove is in the lower level of a trilevel, 14 feet of chimney may not be enough.
Large trees can interfere with your draft causing high-pressure areas around your chimney. Also, you could have air leaks in your house, causing air to rush out various cracks creating a lower pressure around your stove. Opening a window slightly sometimes helps, but it must be on the pressure side of the house. Opening and closing doors of certain rooms can sometimes affect the air pressure in a house as well.
