A complex job is defined by what’s missing:
adequate headroom in most of the space, say, or lack of a staircase (or limited room to add one on the floor below). The older the house, the more likely that renovation will require increased structural support. You may even need to raise the roof. The simplest conversions are those where the attic already has adequate headroom, a floor (or subfloor), adequate light and window space, and access by way of a fixed stair. Chances are the joists under the floor will need reinforcement, the stair may not meet modern building codes, and livability will demand more windows than the required minimum. If walls and ceilings are clad in beadboard— a common treatment in the attics of many early-20th-century houses—that will need to be removed so that insulation and wiring can go in.
Complex attic conversions are defined by what’s missing: adequate headroom in all or most of the space, or the lack of a staircase (or limited room to place one on the floor below). The older the house, the more likely the renovation will require increased structural support—both underneath the floor and between roof rafters. In some cases, adapting the attic for living space will mean raising the roof itself.
Other tough conversions include attics where trusses or the roof profile make it all but impossible to meet minimum head heights. Dormers and bump-outs can help, but they add substantially to the overall cost. From an architectural standpoint, they can also be tricky to design and place because they alter the roof profile.
“There are innumerable ways to do a dormer wrong and only a few ways to do a dormer right,” says architect Frank Shirley, who designed the attic expansion on p. 38 (see “The Gambrel Attic”). A dormer should be large enough to bring in light, but not so tall
For a smallish, 200-year-old house overlooking the ocean north of Boston, the attic was the only place to expand. Even though the gable was so shallow that someone 6’ tall couldn’t stand upright at the ridge, zoning and conservation setbacks made any other type of addition to the two-storey, 1,600-square foot house impossible.
The solution was to literally raise the roof, giving it a gambrel profile. “We created a different roof that would have been appropriate for that time,” says architect Frank Shirley.
The new profile not only allowed the project to meet headroom requirements, but the shallow, slightly sloped sidewalls inside also are ideal for the placement of period-correct dormer windows that let in light.
Rebuilding the attic frame to support the new roof came with its own pitfalls. “The contractor actually had to work really fast, using trusses prebuilt on site so we could get the new roof on in just a couple of days.” Timing was essential to protect the finished rooms below.
Sometimes wood alone cannot support the weight of a reconfigured space. Here, “we introduced a structural bent, a steel beam that’s welded in the shape of a gambrel that occurs where those tie-rods are. That’s what’s keeping that gambrel roof upright,” the architect explains.
Tie-rods that run the full width of the house, and that work by tension, are a traditional means of ensuring structural integrity. “The turnbuckle in the middle allows a certain amount of tension in the tie-rod itself, but it shouldn’t be too tight.”
To the owners, the expansion was worth the trouble. Of the balcony, Shirley says: “That was 8 square feet of the best real estate ever built.”