What to Look For in Selecting Range Hood

QUESTION: We’ve been looking at kitchen range hoods, and aside from styling and some features, such as lighting and number of fan speeds, almost all the models seem very similar. Are there real differences between range hoods, and if so, what should we be looking for?

ANSWER: The only real difference between one range hood and another is the way it deals with the stale air it captures. Some hoods filter out the moisture and grease before returning the freshened air to the room. Other machines dump stale air outside through a duct in the wall, just like a conventional wall-mounted exhaust fan.

Because the air is actually changed, extraction is the more efficient method, but it is necessary to cut a hole through the wall and, of course, the heated air is lost--excellent in hot weather but rather a waste in winter. Range hoods that recycle the air are much simpler to install but never filter out all the grease and odors, even when new. It is essential to clean and change the filters regularly to keep the hood working at peak efficiency.

How to Dispose of Asbestos Shingles

Q: We own a 1950s-era house that has asbestos shingles on the sides and back and vinyl siding on the front. The shingles are in good condition, but we are concerned that they would be a factor in selling our home. If the shingles are removed, will their disposal be difficult?

A: Although the shingles are referred to as asbestos, they are really asbestos cement shingles. That is, the asbestos fibers are encapsulated in cement. As long as the shingles are in good condition there is no problem. However, if they are abraded or sawn, asbestos fibers can be released.

If these shingles are in good condition, they are generally not a factor when the home is sold. Nevertheless, there will always be buyers who will try to make the shingles a part of the sales negotiation. Even if the shingles are in poor condition, they don’t have to be removed. You can install new siding over them.

Removing the shingles is expensive, since the work must be done by a licensed asbestos removal contractor. The waste will have to be disposed of in a landfill designed to take this material.

How to Stop Dark Lines on Ceiling

Q: There are dark lines on the drywall ceiling below the attic in my house. The lines coincide with the ceiling joists. Someone suggested it is due to the lack of insulation. However, we have 6-inch batts in the attic. Do you have a cure for this problem?

A: Although you have insulation between the joists in the attic floor, the top of the joists are exposed to the cold winter temperature in the attic. Since the wood joists are not effective insulators, they act as thermal bridges. Consequently, the temperature at the underside of the joists (at the drywall ceiling) is cooler than the adjacent sections of the ceiling, which are covered with the insulation batts. Because of the lower temperature below the joists, condensation (however slight) tends to form along those areas. Over time, the moisture traps dust and also results in mildew growth, which shows up as shadow lines.

To prevent this from recurring, first paint the ceiling. Use a paint containing mildewcide. Next, install insulation batts over the exposed ceiling joists. Ideally, the insulation should fill the spaces between the joists and cover the top of the joists as well. This last layer of batts is often installed perpendicular to the floor joists.

However you install the insulation, make sure to use a type that does not have a foil or kraft paper vapor barrier. And be sure additional insulation does not cover soffit vents or recessed light housings (unless the housings are IC types rated for direct contact with insulation).

How to Repair Mortar Joints in Brick Walls

Q: The mortar joints on the brick walls of my house are dried and crumbling. How can I repair this?

A: The repair procedure for mortar joints on brick is known as “tuck pointing.” Start by chipping out all the loose mortar from the joints with a cold chisel and hammer to a depth of at least 1 inch. Clean away dust and chips with a water jet and wire brush. In areas where failing water is causing mortar leaks, remove the bricks and clean mortar from remaining bricks in the surrounding area.

Mix mortar from one part portland cement, one-half part hydrated lime, 4 1/2 parts sand and enough water so that the mixture can be compacted into a ball. Let it stand for one hour, then add enough water to make a stiff but workable paste. Dampen joints with clean water. Use a jointing tool to force the mortar into joints. As you compress the mortar and strike off the joints with the jointing tool, work in one direction only to avoid forming air pockets.

For further information on any home problem, write to Popular Mechanics, Readers Service Bureau, 224 W . 57th St . , New York, N.Y. 10019.