Site assembly. We loaded all the components onto a truck and hauled them to the site. On installation day, with a crane standing by, we cut back the existing roof overhangs and exposed the top plates where the new roof would connect. We set the steel I-beam with the crane, and a welder completed the moment frame. Meanwhile, the crew set and bolted the architrave beams on the columns. By late morning, we were ready to set the roof sections, beginning with the cone. We’d already outlined the MDO plate’s location on the underside of the truss chords, making it easy to accurately re-establish the overhangs on site. We secured the cone to the architrave with 3-inch Timberloks, screwing up through the plate into the bottom chords.
The architrave is supported on 4x6 pressure-treated posts within the architectural columns, notched to 4x4s where they pass through the beam.
The only straight section in the architrave is made with doubled LVL lumber.
Welded brackets support the beam at the moment frame.
We installed the remaining roof modules in the same manner. By late afternoon, we had all the structural pieces set and bolted together. Last but not least, we hoisted the “bat” onto the cone, nailed it in place, and called it a day. Later, I went back with a reciprocating saw and notched the plate to install hurricane ties between the beam and each truss.
While the welder put the finishing touches on the moment frame, the crew set the roof modules around the architrave.
Each module included a recess to encase and bear upon the moment beam.
Metal plates tie the architrave to the steel posts; wood post locations were tied together with plywood overlays.
A slight built-in tolerance allowed the center module to drop in without resistance.
The “bat” module defines the valleys and completes the cone.
To complete the structure, the site crew filled in a few jack rafters between the truss assembly and the existing roof, then sheathed the underside with 3/4-inch plywood. This plywood, glued and nailed, serves as a tension diaphragm tying the bottom chords together to prevent the structure from spreading and settling. It was later covered with a beadboard ceiling.
All I had left to do was install the curved crown moldings, a detail that gave me an unexpected run for the money (see “Bending Crown”). Altogether, the work described here required 600 man-hours, or five weeks for a three-person crew.
Mike Rand runs a specialty millwork shop in Narragansett, R.I.