Wood-framed residential buildings rely on the continuity of weather barrier and roofing assemblies to protect structural materials from decay. Three-dimensional, complex intersections can pose design and construction challenges. An important but often overlooked detail is where roof gutters meet rising walls, requiring a kick-out flashing to divert water traveling down the edge of the roof into the gutter, especially when using materials such as wood, stucco, cement board, or vinyl siding.
Many industry groups recommend kick-out flashings, and various prefabricated options for three-sided flashings are available; however, they are not consistently used where needed. Two recent projects show the severe consequences when this critical component is omitted, leading to significant structural deterioration only a few years after construction.
The first project was a stucco-clad residential building in the Midwest. At various gable-end locations, the walls rise above the roof as a low parapet wall, and the hanging gutter assembly terminates in line with the inside face of the parapet (Figure 1). No diverter flashing was installed, and water was able to penetrate the top edge of the stucco at this corner and migrate into the wood-framed wall. The owner remained unaware of the issue due to closed-cell spray foam insulation in the stud spaces. The deterioration of the oriented strand board (OSB) sheathing became widespread before it was discovered, necessitating extensive repairs and the replacement of large areas of stucco.
The second example was an apartment complex in the South. Various cement board cladding profiles were used, with each unit having a projecting bay that abuts an adjacent roof with a hanging gutter (Figure 2). At this key transition, the lack of a diverter flashing allowed water from the lower roof to bypass the gutter’s end and penetrate the cement board cladding and trim. Within a few years, severe damage had affected the wood-framed structure, leading to the replacement of all cladding at the perpendicular wall and structural repairs to the wood sheathing and framing (Figure 3).
In both cases, the addition of a kick-out flashing at the gutter termination would have mitigated most, if not all, of the water infiltration, avoiding extensive and disruptive structural repairs. Within less than 10 years after initial construction, both projects experienced considerable damage to the wood structure, demonstrating the critical importance of the kick-out flashing detail for the performance of the wall and roof assemblies.
Kenneth Itle, AIA, is an architect and associate principal with Wiss, Janney, Elstner Associates (WJE) in Northbrook, Illinois, specializing in historic preservation. He can be reached at kitle@wje.com.
The opinions expressed in Failures are based on the authors’ experiences and do not necessarily reflect that of The Construction Specifier or CSI.
