Old basement floor tile should not be disturbed

Q. Back in the summer, some 20 years ago, water got in my cellar. There was carpet on the floor as well as a pad. The water soaked the carpet and seeped into the bottom of the drywall. While removing the carpet and pad I found vinyl tile squares had been laid on the cement floor. I am not sure when this tile was installed. Now there are two things I am worried about. One, is there a good chance the tile may have asbestos in it. Two, I am a bit worried about mold. There are some faint black spots about 6 inches up the Sheetrock from the floor in some places.

I would like to cover up the tile with some kind of seamless floor like linoleum. The cellar hasn't gotten wet since then. Is this a good idea or should I have the tile removed and put linoleum directly on the cement? What would be the best flooring to use? What should I do about the mold on the drywall?

A. There is no need to remove the existing floor tiles if they are not loose, and, yes, they may contain asbestos; the more reason not to disturb them. Linoleum cannot be successfully installed over the tiles.

The best approach is to have a professional floor company lay a special sheet vinyl flooring such as manufactured by Armstrong or Mannington that is installed dry (without adhesive) and able to lay flat without curling.

As to the affected drywall, it should be cut above the moldy area, the substrate checked for moisture damage and, if needed, the underlying framing treated with bleach, allowed to dry and new drywall installed.

Q. We had a new driveway poured about four months ago, which we had sealed with Saltguard sealer. I was fertilizing the lawn with Scotts Max Green with Iron Supplement fertilizer when it started to rain. After the rain stopped, I noticed a rusty color stain on the driveway. How can I remove these stains?

A. The iron in the fertilizer caused the rust stains when it got wet. First, try brushing the affected areas with a solution of equal parts water and fresh bleach. If that does not completely clear the rust spots, increase the proportion of bleach to water. This should take care of the rust spots because they are relatively fresh. But if it does not, there is another chemical, oxalic acid, which you can use, but it is more caustic and needs to be used with great caution.

You can buy oxalic crystals from paint and hardware stores; you won't need much. Wear skin and eye protection, and old clothes. Mix the crystals to saturation (until some crystals can no longer be absorbed) in hot water in a plastic bucket - never use metal containers or tools with oxalic acid.

Apply the mixture with a stiff-bristle brush with a long handle. Give it a chance to do its work; it may take 20 to 30 minutes. When satisfied with the results, rinse the treated areas. Dispose of any remaining solution environmentally. The treated areas may be lighter than the rest of the concrete, but they should eventually match.

Q. My father used a pencil on the composite decking we were installing and nothing we have tried removed the pencil markings.

I called the manufacturer where my father purchased the decking and they said to use soap and water, but this didn't work at all. We tried Goo Gone, but this product removed the finish. We were also told that the pencil marks should weather over time. My father purchased the composite decking at Home Depot in a walnut finish. What do you think? We are lost!

A. Make a pencil mark with the same pencil on a piece of scrap decking and try to remove it with WD-40. If this does not hurt the finish, try it on the affected deck board.

Q. I have read a few of your case studies and other online sources that point back to your expertise. I was wondering if I could trouble you with another case.

I purchased my current house just over a year ago. It is one of many identical ranch houses in the neighborhood with cathedral ceilings (pitch, 1 inch per foot) built in the 1960s. What caught my attention last fall was that there were icicles hanging from underneath the soffit in the cold fall/early winter without any precipitation. Especially large icicles were hanging around the kitchen area. I do remember a softer feel in walking the roof in the summer, also above the kitchen. From my research I understand that this type of non-vented roof is called a "hot roof" and could be very dangerous.

My question is, how did the roof last as long as it did? And am I the only one in the neighborhood that has that problem? And the most obvious question: How do I fix it (on a budget)? I know the costliest would be to remove the existing roof and redo it correctly with venting. However, are there any other alternatives?

A. I can't answer the question about your neighbors, but your roof's structure has been rotting slowly and the obvious reason is moist air from the conditioned space convecting into the hot roof with no way to escape and no way for the framing, roof decking and insulation to dry up.

Over the years, the roof sheathing has deteriorated and lost some of its strength, which is why it felt soft when walking on it.

The icicles tell us there is a lot of condensation on the roof sheathing that is draining and freezing as it reaches the soffits. The icicles are larger over the kitchen because that is where a lot of moisture is generated and is convecting into the attic through a number of possible paths, such as improperly sealed wall and ceiling joints behind wall cabinets - often neglected.

The fix is likely to be very expensive. The roof should be opened, any decaying roof sheathing removed, wet insulation disposed of and the rafters checked for damage, which may require extensive repairs, possibly sistering new rafters to them.

If the entire roof is affected, you may want to consider including ventilation - quite an undertaking, but it is unlikely to be very effective on such a low pitch roof. A better solution would be to replace the existing fibrous insulation with closed-cell urethane; it is almost completely impervious to moisture. You should notice a great improvement in energy savings.

When all is fixed, you should also consider having an energy audit to locate any and all convective paths and seal them to avoid further problems.

Check your homeowner insurance policy; it may cover the cost of repairs.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of "About the House with Henri de Marne" (Upper Access Publishing). He continues to take questions from readers for this column and his website, www.henridemarne.com. Email questions to aboutthehouse@gmavt.net.