Dana Patterson has been building houses in and around Merrimack, N.H., for 31 years. In that time he has become one of southern New Hampshire's larger builder/developers, heading a company that at its busiest a few years ago did over $5 million in business, 90% of it residential. While he is primarily a stick-builder, he has been using modulars for selected projects since the early 1960s. We recently talked with Patterson in his Merrimack office to get his views on the business pros and cons of building with modular. JLC: The big question most people wonder about: On a given house, do you really save money with modular? Patterson: It depends on circumstances. We're already in business, so we