Aug. 3--Kenneth D. Rosen has been a real-estate investor in greater Miami for 40 years. All the while he employed a formula for buying property, but he did it intuitively. Not until he was asked to give a talk before a Realtor board several years ago did he actually write down his investment principles.

In the past year, he expanded on those notes by putting into book form what he calls his "Big Six" investing guidelines. His book Investing in Income Propertieshas even caught the attention of an Egyptian publisher and is being translated into Arabic.

Rosen claims the principles, if adhered to closely, will produce consistently solid results in good times and bad. Even now, amid the real estate crunch, he's buying -- having recently purchased a Coral Gables office building.

The Coral Gables investor spoke with The Miami Herald about his principles for real-estate investing, the process of writing and publishing a book and his four decades of experience in Miami real estate.

Q: What is the formula that you've used for many years that you wrote about?

A: There are six. With each one, if it's not there, you stop and you don't buy.

The first is location. I recommend buying in an A location. Examples would be Coral Gables -- particularly the south end of Coral Gables, South Miami, Dadeland, Aventura, the Roads, Coconut Grove. These are established areas where there is little land left to build on. Areas that have a prestige element. Not necessarily very expensive homes but an area looked upon as having stability over the years.

Second, quality built and efficiently designed. I buy B buildings. The difference between A and B buildings is A buildings are owned by people who want an image. Some A buildings downtown have huge lobbies, for instance. These people are concerned about corporate image. B buildings don't have the frills. In A buildings there is an awful lot of wasted space. Forty percent of the building is lobby, hallways, that kind of thing. Whereas an office building to be economically efficient should have about 15 percent common areas.

And the parking situation. You usually have to go up in a garage, then take elevators. It's an obstacle course and lot of people want to stay away from them. For every 1,000 square feet, you have three parking spaces. Better to have four to one. But three to one will work.

B buildings obviously have to be constructed well but the design is also very important. It should be pleasing to the eye.

Third, tenant profile. There are very few vacancies in the buildings I just bought.