Belsay Hall - Northumberland

A Full Roof Replacement of Belsay Hall, Northumberland

Project Overview

Belsay Hall, a Grade I listed Greek Revival mansion in Northumberland, underwent a full roof replacement as part of a major conservation project. With a low pitch roof of just 12°, the historic 900m² structure had suffered years of water ingress due to its exposed location and driving rain. The two-year restoration aimed to protect the building while preserving its original aesthetic, true to its design from the early 1800s.

The project also faced the logistical challenge of keeping Belsay Hall open to the public throughout the refurbishment, requiring careful planning and execution to minimise disruption.

Project Requirements

The key goals of the restoration were:

• Preserving Aesthetics: Maintaining the original appearance of the roof to align with its early 19th-century design.
• Addressing Water Ingress: Providing a reliable solution to combat water damage while improving structural integrity.
• Material Conservation: Salvaging and reusing undamaged historical Westmorland slate where possible, with replacement slates matching the original in appearance.

Execution and Process

To ensure the building remained watertight throughout, a full free-standing scaffold roof was erected, creating a weatherproof environment during the restoration. The work was carried out in phases:

1. Main Hall: The roof was stripped, allowing for timber and masonry repairs.
2. Kitchen Wing and Link Areas: Each roof elevation was stripped and repaired sequentially to maintain stability and protect the structure.

Slates removed from the roof were carefully assessed the usable Westmorland slates were graded for reinstallation., with all the smaller or damaged slates retained for use on other English Heritage properties. The contractors’ joinery team, guided by the Conservation Architect and Structural Engineer, repaired roof timbers as required. Sarking boards were installed, and debris was cleared from roof voids, preparing the structure for re-slating.

A skilled roofing team, experienced in working with Westmorland slate and leadwork, completed the reinstallation of slates and detailing.

Roofing Solutions

The specification included:

• Westmorland Slate: Salvaged where possible, preserving the building’s historical materials.
• Burlington Blue Slate: Used as a replacement for damaged or unusable slates to match the original appearance.
• Waterproofing: The Easy Slate system was specified to protect the low pitch roof from wind-driven rain preventing water ingress, while remaining invisible to maintain the roof’s historical aesthetics.

Permavent also provided technical advice to material suppliers and the architectural team on roofing technologies, helping to ensure the project adhered to both performance and conservation standards.

Challenges and Solutions

1. Low Pitch Design: At just 12°, the roof required specialised waterproofing to prevent water ingress. The Easy Slate system met this challenge effectively.
2. Preservation of Materials: Salvaging and reusing original materials required careful handling and expertise to retain the roof's character.
3. Public Access: The building remained open throughout the restoration, requiring phased work and strict safety measures.
4. Structural Repairs: Ongoing assessment and repair of roof timbers and masonry ensured the building's long-term stability.

Outcome

The completed project successfully restored Belsay Hall’s roof to its former glory, preserving its historic character while providing the durability needed to protect the building for years to come. By blending modern waterproofing technology with traditional craftsmanship, the project maintained the mansion's heritage while addressing its structural challenges.