Conservation Architect: Restoring Timber Frame Hip Roof
Conservation Architect Challenges at Orleton Manor - Working with Oakley Frame Buildings
At the heart of Orleton Manor, the intricate hip end where the kitchen wing meets the hall range presented a significant repair challenge for us as conservation architects. The hipped roof structure, resembling a tent or pyramid without gable ends, typically allows the roof's forces to be self-bracing, directing the load towards the building’s centre.
However, the U-shaped plan of this historic building, including complex timber frame elements, introduced complex valleys at the intersections, essentially the inverse of hips. Each junction featured dual trusses, comprising both a hip rafter and a valley rafter, adding layers of complexity to the conservation efforts.
Structural Dilemmas and Innovative Solutions in Timber Frame Conservation Over the years, numerous modifications had compromised the integrity of Orleton Manor's timber frame roof structure. Key structural members were found to be cut out, decayed, or improperly altered, weakening the essential ties across the corners of the building.
As depicted in our images, most roof members were previously cantilevered, failing to reach the apex. This was due to historical adjustments made to accommodate the evolving use of the building, including the expansion of living spaces. Notably, a critical purlin connected to the hip rafter had failed, subsequently replaced with an inadequately sized section.
Similarly, the valleys bore the brunt of extensive cantilevering, particularly notable in a large purlin that terminated short of the truss line. Valleys, being convergence points for water run-off, are prone to decay and structural failures, a common challenge for conservation architects working on timber frame buildings.
Reinstating Structural Integrity Following the reinstament of the roof trusses, repair efforts by Oakley Framed Buildings, guided by our engineer’s detailed drawings, focused on reestablishing the crucial connections between the building’s structural members. Instead of merely adding new pieces to each compromised section, a boss post was introduced, facilitating a comprehensive connection among all timbers.
Replacements for the deteriorated or missing purlins were crafted with precision to match existing members, including a dovetailed end that seamlessly connected to the hip rafter. This meticulous attention to detail not only preserved but enhanced the structural resilience of the hip in the timber frame building.
Detailed close-ups within our blog highlight the hip's intricate patch repairs, the scarf repair beneath the purlin, and the reinstatement of a principal rafter into the vacant mortice pocket. This critical addition helped anchor the ridge and provided a secure landing for the purlins.
Continuing the Craftsmanship Tradition in Building Conservation
The project culminated in the installation of two robustly engineered valley boards, set to outlast any subsequent roofing material. This phase of the restoration underscores the complex interplay of advanced engineering and traditional craftsmanship—a hallmark of skilled conservation architects.
Orleton Manor's repair is a testament to the expertise of our carpenters and the innovative approaches of conservation architects and engineers, dealing with the challenges presented by 400-year-old timbers that exhibit natural twists and bows.
Looking Ahead
Stay tuned for our upcoming detailed post on the Dragon Tie's impressive steelwork and the construction of the boss post, illustrating further the complexities and triumphs of conservation architecture.
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