Q: Recently you said that a chimney cleaner or sweep must go up on the roof. The one sweep I called said he wouldn't go up on my roof because it's slate. What do you suggest ? A: The main reason for a sweep's working from the roof is that it allows him to inspect the chimney. He can clean it very well working from below. If you are only concerned with cleaning, use a sweep who works from the fireplace opening; but if you want a complete inspection as well as a sweeping, find another sweep.

Since slate roofing is slippery, and easily broken underfoot, he should work from a ladder equipped with ladder hooks, to protect him and your roofing. Q: What can be done to eliminate the rust forming on the metal around the drains of our enamel sinks, tubs and wash basins and discoloring the enamel in the surrounding area? The sinks, tubs and wash basins show no signs or wear other than the rusting metal drains. Installation of new ones is beyond our means . A: There should be no need to replace those fixtures. The drains themselves are not rusting; your problem is rusty water. Either the water is rusty to begin with or it's picking up rust from iron pipes in your home. In either case you should be able to solve the problem with the help of a water conditioning company. Check the Yellow Pages for help under "Water Softening & Conditioning Equipment & Supplies." Q: In cold weather our water pipes freeze up. Neighbors with identical homes don't have the same problem. The pipes run through a low, narrow bay area that extends a few inches beyond the basement. We've tried packing this space with fiberglass insulation but it hasn't helped. Could you comment ? A: I'm surprised a builder would run pipes through exterior walls in your. part of the country. It's not very good practice. But that's past history -- the problem now is to eliminate the freezing problem, and since your neighbors seem to be getting by there should be an easy solution. I assume, first of all, that when you added the insulation you put it between the pipes and the cold exterior wall. If not, remove it and do so.

If possible, pull the pipes as far away from the exterior wall as you can and secure them with pipe supports or blocks of wood. Do not put any insulation between the pipes and the heated part of your home. You want heat from the rest of your house to reach the pipes.

If you can locate some urethane foam insulation, use that instead of fiberglass. It will do a far better job of insulating. Use as many layers as you can fit between the pipes and the outer wall. If you can't find urethane, use styrene foam.

I think that will solve your problem. If not, your best bet would be to use electrical heat tape wrapped around the pipes. This will protect you unless you have a power outage. Q: My neighbors had urea-formaldehyde foam insulation pumped into the walls of their cement block home, about a year ago. Now their two small children have a respiratory infection that has been going on for months. Their pediatrician treats it, but it still persists, with stopped-up noses and coughing. Could this be connected with the foam? It is thick cement in the walls, and we have never noticed an odor from the foam . A: I am certainly in no position to diagnose health problems, but I would guess the foam is not to blame. True, U-F foam has caused some problems; but according to the evidence I know of, the trouble occurs when the foam is improperly installed. In that case, the distinctive odor of formaldehyde pervades the home, and in some instances, chemical bronchitis can result.

But since your neighbor can detect no odor, the respiratory problems most likely have another cause. Still, it would be wise of your neighbor to explain her situation to the pediatrician if she has not already done so. Q: I bought one of those kits to increase the insulation around my water-heater tank. Now I've heard that adding extra insulation can be dangerous. True or false ? A: Extra insulation can be hazardous if it's applied incorrectly. According to the Underwriters Laboratories, the extra insulation may trap enough heat to raise the temperature around electrical components and wiring inside the heater jacket, and around house wiring boxes mounted on the heater. If the heat gets high enough, it can damage insulation.

To prevent this possibility, UL says that insulation should not be applied over access covers to water-heater controls, or over house wiring terminal boxes. The installation instructions for water-heater insulation kits that I have seen warn against covering access plates and boxes, so if you followed your instructions, you should be safe. Better check your work to make sure, however. Q: One of the sinks in my home makes a sucking sound when it drains. Sometimes the bathroom it's in has a strong smell of sewage. Is there anything I can do about these two annoying problems ? A: Sounds to me as if your sink plumbing is not properly vented. In addition to the pipe that carries off waste water, the sink should also have a vent pipe, which allows air to enter the system and prevents the water in the trap from being sucked down the drain pipe by momentum or siphon action. That sucking you describe is a good sign you have no vent -- even if you do, you won't be able to see it since it will be inside the wall.

If I were you, I'd call in a plumber. Your lack of a vent is sucking water out of the trap and allowing sewer gas to enter your home That's not only unpleasant, it's unhealthy and dangerous.