You keep talking about curb appeal as a way of getting people to look at a house for sale, but I don't really understand what you have to do to obtain curb appeal? How does it work?

Answer: The National Association of Realtors said in the past - and I think it probably is even more necessary in this market, with so many more houses for sale - that 49 percent of all successful sales began when the prospective buyer pulled up in front of a house to admire it, and then was intrigued enough by what he or she saw to walk through the front door and see more.

Veteran real estate agents who have experienced all kinds of markets know what sells a house from the curb, and can suggest ways of making your front yard ready for showtime. They also know enough to suggest when your yard needs professional help from a landscaping company to get things looking spiffy.

Sometimes it's as simple as ordering a couple of cubic yards of mulch from the local nursery and keeping it watered to look fresh. Other times, curb appeal will require removing brush and cutting tree branches away from the house, repairing sidewalks, replanting grass, and painting.

Downtown dwellers usually don't have to worry about yards, but front steps, doors, windows and shutters should be sparkling clean and painted, and the brass knobs and door knockers should be polished. If you don't have window boxes, you can pick up some wooden ones or other containers at a home center and fill them with flowers.

Q: I have a flat roof about 25 by 10 feet over a home office. Is a rooftop garden feasible, or could I put potted plants on the roof? I live in Philadelphia and want to keep the area shaded in the summer to keep the temperature of the office down.

A: If you want to build a roof deck and fill it full of potted plants, you first have to check on the municipal permit process - and perhaps have an architect check it out, to make sure that the building is structurally sound enough to take the additional weight.

I don't think a roof garden or a deck full of potted plants would contribute all that much to keeping the home office cooler, however, although I think it would probably improve the look of the house and, depending on where you live, provide interesting views or offer an outdoor area on which to relax or party in the summer (remember, architect, structural engineer, and permits).

A more sensible method of cooling the space below the roof is by adding a white elastomeric coating that reflects the sun. An elastomeric coating is one with rubberlike properties that will return to its original dimensions after being stretched or deformed. The coating will expand and contract with the surface to which it is applied.

Usually two coats, each 10 mils thick, are required. Once applied, the coatings - each dries in two to eight hours, depending on the weather conditions - continue to bond to the roofing material. The top coat wears away through normal weathering, and should be reapplied every 10 years.

Many roofers are unaware of the coating or stay away from using it, preferring traditional methods. You might look on the Internet for companies in your area that will do it, although a former editor of mine and her husband applied the coating to their own roof and she reported afterward a noticeable drop in their electric bills.

One report I've seen said that the temperature of a roof dropped from 137 degrees to 80 degrees after the coating was applied.

Have questions for Alan J. Heavens? E-mail him at or write him at The Inquirer, Box 8263, Philadelphia 19101.