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Handyman on call | Peter Hotton

Applying joint compound; fixing smoke alarms

Q. 1. When applying joint compound, I end up with small holes. What is wrong with my technique or the joint compound? 2. In your Nov. 18 column, you stated that in northern areas, black or light-colored shingles will not affect the house (I suspect you meant the temperature on the top floor). However, in southern climes, light-colored shingles help reflect heat. What makes this difference? I now have dark-colored shingles on my house in New England.

A. 1. I’m not sure why you get holes or bubbles when you apply joint compound, but I will guess: Is the joint compound premixed? If not, you have not mixed it thin enough. Otherwise, it may be your technique, or the compound may be applied too thick or too thin. No matter what, when the compound dries, sand off the holes or bubbles.

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 2. The difference is that dark and black shingles absorb heat, and lighter colored shingles reflect heat. In northern climes, the color of the shingles will make no difference as long as the attic is adequately ventilated to prevent buildup of water vapor and heat.

Adequate ventilation is several vents venting the attic.

Q. My son built a very nice looking ­Adirondack chair in his wood shop, but it was varnished with an indoor polyurethane varnish. Can I put an exterior paint over it so I can use it outdoors?

A. Not really, because the varnish would peel under the paint. So, try this: Use a stripper such as Citristrip that is a citrus based remover. It will be much faster than sanding. Then apply a semitransparent stain. It will last seven years and will not peel. Then apply another single coat. It will also guard against decay.

Those screaming smoke alarms

 When “Mr. Annoyed” asked about his hard-wired, battery backup smoke alarms going off frequently, the Handyman answered that changing the batteries usually helps, but forgot to mention one of the most common causes of failure: dirty detectors. So, clean out all units with canned air or a slight blowing from a vacuum cleaner. This week he received more ideas.

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 Wrote bdr: The life expectancy of batteries, and most warranties are 10 years. One of mine, in a six-year-old home, would sound erratically and intermittently despite changing “long-life” batteries a few times. I called the company, which after reviewing information printed on my unit, sent me a free replacement! I suspect Mr. Annoyed’s units may be older than the Americium radioactive substance’s viable life. The latter powers the detector.

 From Captain Joe Zukas of the Lynn Fire Department: Heat does not make a smoke detector activate. Most commonly smoke or steam from a stove or from a bathroom shower can set smoke detectors off. Smoke detectors come in two types: ionization and photoelectric. Photoelectric are less sensitive and have two mirrors which have a beam of light shining from one to another. Smoke breaks the beam of light and sets the detector off. On rare occasions spiders or dust could activate them.

 Ionization units are more sensitive and should not be put near kitchens or baths because they will go off from non-fire situations. These detectors have a small amount of radioactive material to create an electrical charge, when smoke enters the detector it changes the electrical charge and activates.

Only heat detectors and sprinkler heads are activated by heat.

 Greg Smizer, who owns an alarm company, said that if people replace their alarms, all detectors on the circuit need to be upgraded at the same time in order to make sure they work in tandem when one of the detectors screams, squawks, chips, chortles, or whistles.

Q. One of my tenants has painted the wall behind his electric range, and there is enough heat to bubble the paint. Admittedly the stove is very close to the wall, even touching it. What can he do to prevent this bubbling? I had a good strong piece of steel that could go behind the stove, but a metal worker said it was too big to fit into his folding press.

A. Pull the stove out 2 inches from the wall, to provide air circulation. And, if he can find the right color, spray with Krylon’s HHR (High Heat Resistant) paint. Other solutions: ceramic tile (worked for me) or a sheet of Formica applied with fire-resistant contact cement.

Peter Hotton is also in the g section on Thursdays. He is available 1-6 p.m. Tuesdays to answer questions. Call 617-929-2930. Hotton (photton@globe.com) also chats online 2-3 p.m. Thursdays. To participate, go to www.Boston.com
Peter Hotton is also in the g section on Thursdays. He is available 1-6 p.m. Tuesdays to answer questions. Call 617-929-2930. Hotton (photton@globe.com) also chats online 2-3 p.m. Thursdays. To participate, go to www.Boston.com

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