Our company, which specializes in structural repairs, was recently called to an expensive residence outside of Chicago. A number of contractors had been to this house to bid on replacing a large wrap-around deck, but they had concerns; extensive rot of the ledger board signaled deeper structural problems that exceeded their expertise. Our inspection revealed numerous places where poor flashing had led to extensive water intrusion problems. The worst was at the base of large banks of windows on the A-frame-style wing that the deck wrapped around. Water running off the large expanses of glass had leaked for years through the base of the window walls, jeopardizing not just the deck ledger but the entire floor-system supports, which served to tie together the A-frame rafters. The house was on a hill and exposed, resulting in significant lateral wind loads on the steep roof, so a rotting floor system put this entire A-frame at risk of collapse.
The original structure appeared to be built with clad, heavy timber rafters that continued past the roof overhang and tied into a clad, horizontal timber beam, which completed a triangle. After we removed the cladding from the rafters, though, we discovered they were constructed from two roughly 3-by-14-inch boards sandwiching a 1/2-inch steel flitch plate welded to a flitch plate in the horizontal member. The floor system sat above this horizontal beam. This design may have worked while the wood framing was sound, but once the wood rotted out, the integrity of the bolted assembly was severely compromised. Rather than try to reproduce this triangular load path, we worked with our engineer on a repair that redefined the load path: By driving helical piers at the same angle as the slope of the roof, the thrust of the rafters would be supported in-line with the rafters. We also supported the floor system with laminated veneer lumber (LVL) beams and completely reframed the supporting walls to create a robust structure with redundant support paths.
Given the tenuous condition of the existing structure and the possibility of the roof spreading as we unraveled the load path, we had to thoroughly shore up the home during the repair. This involved shoring under the entire A-frame floor, as well as erecting shoring towers on the right and left flanks of the A-frame where the main house roof extended over the deck. We also installed a temporary LVL beam across the face of the windows at the base of the triangular gable end.
Like many jobs on existing homes, our repair work touched a lot of the building systems. As seen in the slideshow "Preparing to Rework the Load Path" (above), several of the initial excavations for the helical piers had cable and electric lines crossing them, and one had a waste line that was directly in the path of the helical pier. A section of this pipe had to be removed to set the pier and then replaced once the pier was installed.
The photos in the slideshows show the crucial steps we took to complete the repair and reframe the enclosure. Our work will be followed by several contractors: One will remove all the windows and the remainder of the existing cladding and replace them with a modern WRB, new flashing, new insulated glass units, and new cladding; and a deck builder will rebuild the wrap-around deck.
Photos by Jake Lewandowski
