Keep a house dry, ventilated to stop mold
What is the best way to prevent mold growing in a house or small commercial building?
CURIOUSThat's a good question that has a simple answer. Keep the house or building dry, dry, dry.
There has been a spate of stories recently about toxic mold, how in some cases the building has to be burned down to stop the rampant mold. Some houses may indeed have a major problem, but most do not, and in most cases the homeowner can handle what mold is there and keep it from growing.
It all boils down to keeping the house, including basement and attic, dry, because mold spores are all around us, just waiting to land on a damp surface and grow, feeding on cellulose, wood, paper on the face of plasterboard panels, paint, and many other surfaces. Mold will grow on any surface except glass, unpainted metal, and some high-gloss hard surfaces. Keeping everything dry means eliminating sources of water: basement seepage, leaks from defective or broken siding or a roof, faulty water lines, or defective drains.
Of course, leaks like the above should be fixed anyway; if they are not, the house will go next.
Another source of moisture is condensation: Water vapor is always in the house, created by breathing, washing, bathing, and cooking. Eventually this water vapor will condense on cool surfaces, in basement, living quarters, and attic. In modern houses, which are much tighter than old houses, the problem may be more acute.
Ventilation is the way to stop this condensation. In a basement, ventilate in spring, summer, and fall. At particularly humid times, such as in July and August, use a dehumidifier. Basement ventilation is usually not necessary in the winter because humidity is low.
In attic, ventilate using soffit vents (the soffit is the under part of the roof overhang) and ridge vents to release built-up moisture.
Basement seepage is hard to control. Sometimes it can be controlled by proper grading of the land outside, so it slopes down away from the house. Make sure downspouts discharge water at least 10 feet from the house.
Other leaks in the basement may require installation of a French drain, an interior drain that guides water to a sump and pump in the basement floor, where it is pumped outdoors.
Ventilation is still your best bet, especially in tight, well-insulated houses. In winter, the heat will help get rid of moisture, and in summer, air-conditioning, which is also a dehumidifier, will handle the moisture.
It is a never-ending battle. When you see mold growing, kill it and clean it off with a solution of 1 part household bleach and 3, 4, or 5 parts water. Bleach is toxic and corrosive, so wear skin and eye protection when working with it.
I would like to refinish my hardwood floors by sanding and using a finish. Should I use polyurethane or a water-based product? My kitchen floor is red oak and I have a dog that drips water a lot. Is a hardwood floor a good idea with such a dog?
STEVE BOERIMiltonOK, let's get our definitions right. There are two types of polyurethane, which is classified as a varnish: oil-based and water-based. In my opinion, if you finish the floor yourself, the oil-based polyurethane is better than the water-based varnish. Three coats will do nicely.
A water-dripping dog will mess up that beautiful red oak floor in a very short time, making lots and lots of water marks that are indelible, unless you wipe them up immediately. An area rug might help.
Are the electric roof cables safe? I mean the ones used on the edge of roofs to help drain ice dam water away.
WORRIEDStop worrying, just pay the high electric bill when you run those cables. The cables are safe as long as they are under snow or ice, or on a wet roof. They are a hazard on a dry roof. So pay particular attention when the snow and ice go away.
Do you think do-it-yourself reglazing a bathtub will work? My tub is badly etched by a powerful cleaner that was left under a wet towel overnight. The cleaner actually ate the glaze away, and the finish is very rough.
LAURA COOKPeabodyThere are do-it-yourself kits that can work, but your tub is too far gone for reglazing work, because even an epoxy finish, which is what I think the do-it-yourself kits use, is unlikely to smooth out that rough, pitted surface. Your only recourse, I believe, is to put an acrylic shell over the old tub. This technique is more expensive than professional reglazing, but has the best chance of working for you.
Three of my lally columns, steel posts holding up the main beam in the basement, have developed a severe rust problem, with what looks like liquid rust oozing out of the steel, both high up the column and low down, near the floor. What is happening and how can I prevent further rust? The columns were painted 35 years ago.
D. WINKELMANWestwoodThe rust is not oozing out of the steel, and if the rust has not deteriorated the columns, no problem. Water vapor is condensing on the steel and causing the paint to bubble. Then rust appears on the bare steel. To correct, scrape off all the rust and the loose paint, then prime with a metal primer and finish with an oil-based paint. Since the old paint job lasted 35 years, you have another 35 years to go before any problem occurs.
Another way: Scrape and sand off excess paint and rust; there is no need to remove all the rust, but you can sand as much off as possible. Then box in the columns with four 1-by-5 boards, caulk the bottom of the box where it touches the floor, and at the top, where it touches the beam. The box will keep the water vapor away from the cold steel; ergo, no condensation.
With a lot of condensation in the basement, it would also be a good idea to ventilate it in April, May, and June and in September and October. During dog day months of July and August, when it is too humid to ventilate properly, use a dehumidifier.
I am having a new roof installed, and the roofer suggested installing a ridge vent. We have a squirrel problem, and I am concerned that squirrels might try to gnaw through the plastic ridge vent and into the attic. They have already gnawed away a part of the fascia board at the eaves, which I am keeping my eyes on.
JANICE COOPERUptonA squirrel might do a job on the plastic, but it is tougher than it looks. Besides, asphalt roof shingles are put on top of the ridge vent, making this less likely. I have never heard of squirrels going after ridge vents, so I think if you installed one it would be OK. If they are sniffing around the ridge vent, then cover it with copper (that would look best), heavy aluminum, or galvanized steel.
I just moved into a house with a double porcelain sink. The bottom of the sink has a coating that has a strong chemical smell. It is not mold. What is it and who could fix this problem?
FUNNY SMELLin Anderson, S.C.The coating is probably insulation of some sort. If the coating is factory installed, you may need a new sink. A plumber might be able to remove the coating and apply an odor-free one, or apply an odor-free coating over the coating that is there now. If the sink is new, then the dealer should do something about it.
Peter Hotton is available 1-6 p.m. Tuesdays to answer questions about house repair. Call 617-929-2930. Hotton also chats online about house matters 2-3 p.m. Thursdays. To participate, go to Boston.com. Hotton's e-mail is photton@globe.com.
