Back in the 1950s, butterfly roofs and vertical siding made a conspicuous statement about the home of the future. But even as the Modernist movement was radically changing the outward appearance of houses, underneath, many of them were still framed the conventional way, with old-fashioned sawn lumber. That's the way it was with this season's TOH TV Cambridge project house.
Today, even in traditional-looking homes, the "futuristic" stuff is often the framing itself. And there's a new language to go with it. Besides understanding the true sizes of dimensional lumber—that a 2x4 is really about 1 1/2 by 3 1/2—carpenters now need to know a host of abbreviations: LVL, OSB, I-joist. They also need to understand more about load and force as strong, efficient engineered woods and steel replace milled stock. Then there are the countless metal ties and brackets—more than 1,700 hangers alone—they'll encounter. A house isn't just wood and nails anymore.
A look at the framing done at the Cambridge house by TOH general contractor Tom Silva and his crew gives you a good idea of what some of these newer materials can do: allow for higher ceilings, larger open spaces, and even cantilevered rooms. And while this skeleton of studs and beams will soon be hidden inside new walls and floors, for now it's clear that the beauty of this house is more than skin deep.
Dimensional Lumber:
The stuff that gives your house its basic shape
Advances in building technology haven't eliminated the need for good old sawn lumber—2x4s, 2x6s, 1x strapping, and the like. It's still the dominant material in a house's skeleton. Dimensional lumber (as distinct from lumber made from fibers or veneers) has good compressive strength—it stands up well to force pressing down on it when it's vertical—so it makes excellent studs. But it's the least expensive framing material, so it's also used for the horizontal parts of a wall frame, such as the sole plates at the bottom, the top plates, and the blocking between studs. Interior walls are predominantly made from 2x4s, which are deep enough to fit plumbing and wiring between the studs, while 2x6s make better exterior walls because they leave more space for insulation.
Most dimensional lumber is milled from softwoods like spruce, fir, and pine, then kiln-dried for stability. There are stronger versions, such as straight-grain fir. When combined with metal ties it can be turned on the flat, with its broad face parallel to the wall, wherever there's limited space for a stud. Tom used fir in this manner to frame a cavity for a pocket door. "It costs twice as much, but it won't ever bend or warp," he says. "That's important, because over time, if the stud curves, the door will scrape."
