Concord official: Rafter joint likely cause of sliding roof

The two-story colonial at 11 Pond Place is still missing its roof, but Concord building inspectors at least think they know what happened when the back half slid off Saturday.

Code Administrator Michael Santa said he suspects the connection between the rafters and the attic joists are to blame. The house was built in 1996, and Santa said the roof was attached using a framing detail that was relatively novel and untested at the time, called a “raised rafter plate.” The design allowed for more required insulation in the attic, but left less surface area at the connection between the rafter and exterior wall.

The house was built by ACA Investments Inc., which was previously based in Manchester and built only one other house in Concord. Santa said yesterday that he had been by the other home and was attempting to contact its owners, just to be safe.

ACA dissolved in 2008, according to records from the secretary of state, and Santa said there is no way to know from building records whether it hired a separate company to do the actual framing. A phone number listed for ACA is now used by an unassociated property management company.

Santa noted that his office has received no previous complaints about ACA, and has heard nothing about it from building officials in other parts of the state.

Raised rafter plates, still in use today, allow for an extra few inches of clearance between the rafters and the joist, but at least in the early years, Santa said, the design was not as sound as a conventional model, in which the rafters are connected directly to the joist.

Santa said it’s not yet clear why the connection failed – whether there were not enough nails to begin with, or framers had put them in the wrong place, or any of a host of potential problems.

“All we know is that connection at the edge of the roof failed,” Santa said.

Engineers have come up with a number of design fixes over the years, including reinforcing the connection with galvanized steel straps or extending the attic joists beyond the walls.

The incident was reported early Saturday afternoon. Santa said a preliminary examination suggested that snow had built up on the front half of the roof, which then pressed down on the back half. Eventually the back half must have buckled under the weight, breaking free from the ceiling joists and sliding off.

Attempts to contact homeowners Kristina and Leigh Levine were unsuccessful, but a neighbor said they have found temporary housing. Santa said he had limited contact with the owners while they continued to work with their insurance company and a contractor. The home was unchanged yesterday, with snow still piled along the edges of the exposed attic. The driveway was still taped off.



(Jeremy Blackman can be reached at 369-3319, jblackman@cmonitor.com or on Twitter @JBlackmanCM.)