SAUGUS – Motorists headed along Route 1 north Wednesday morning were in for a surprise if they traveled the same highway in mid-afternoon.Just north of the Chisholm Motel, and diagonally across the busy highway from the famous orange dinosaur, a four-bedroom home was standing amid what was a vacant lot hours earlier.The feat began in the wee hours when four flatbed trucks arrived on the 1288-1294 Broadway site, along with a crane to lift the pre-assembled modules into place. The concrete foundation had been poured last month and long cured. For builder Scott Jones of Saugus and his son, Scott Jr., the event marked the culmination of weeks of negotiations and logistics aimed at bringing a modular demo house and sales office to Broadway.”It’ll take us 8-10 weeks to do the finish,” said Jones, who began his home-building career working for his father-in-law at James V. Caggiano & Son in Saugus, a construction company he now owns.But where Caggiano & Son specialized in stick-built homes – meaning a structure nailed together board by board – Jones’ newest venture is modular construction. As president of Westchester Modular Homes of Greater Boston, Jones intends to build 20-30 pre-fabricated homes each year on the North Shore, Metro West, the northern part of the South Shore and in southern New Hampshire.”I’ve done over 300 of these and other homes over the years but, with this company, our work will be exclusively modular,” said Jones. “We’ll do the design and the build. In fact, this house is what we call our Bostonian model.”The gray vinyl-shingled Colonial encompasses 2,900 square feet, not including the optional two-stall garage. In addition to four bedrooms, the home has 21/2 baths, staircases that wend their way to the third floor as part of an open-ceiling plan, a fireplace in the family room and a kitchen with breakfast nook.”Basically we will build whatever people want. The only difference is that we order the units. Everything can be customized, from the windows, woodwork and cabinets to the bathroom fixtures,” said Jones, noting that his wife Lisa will do the interior decorating at the showroom.Jones said one bedroom will be decorated for a boy, another for a girl, a third as the master suite and the fourth for a guest. The master bathroom in the Bostonian model features a jacuzzi. The walk-in closets are standard, as are the Anderson windows.”We have already built 15 modular homes in Saugus,” said Jones. “This one cost $1.2 million for the land and the house. It’s a more high-end model. But we can build everything from a 1,200-square foot ranch to houses with 6,000 square feet.”The company has modular homes in various stages of construction in Concord, Topsfield, Malden and in Boston’s Dorchester neighborhood. When the houses arrive at the locations, the roof shingles are attached, the drywall board fixed to the studs, the staircases pre-assembled and ready for installation. Even the ceiling light fixtures are boxed and ready for hookup.According to Jones, most companies specializing in modular home construction do not have a full house as a showroom and an adjacent sales office. “We wanted this on Route 1 so that people can come and see what it’s like, see the quality that goes into these units,” he said, explaining the misconception of modular homes as glorified house trailers may still exist in some quarters but has no basis in reality. “Everything that goes into one of these homes is high quality and they’re energy-efficient.”To emphasize, Jones points to the thermal window and door glass, oak staircase trim and heavy-duty door hardware.”This house has never seen a storm,” he said Wednesday during a tour of the prototype. “It came out of the factory yesterday and today it’s standing here while we put the final touches on it.”The modular construction allows Jones to offer a price discount because the labor costs involved in stick-built carpentry can rise quickly, especially for detailed work such as staircases and wi