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Case Study
West Dean College of Arts & Conservation (Phase 1)

West Dean College of Arts & Conservation has an outstanding profile for arts, conservation and education, and is regarded as a centre of excellence. Founder and surrealist Patron Edward James and is now part of the Edwards James Foundation.

Each of the 39 roofs varied in pitch and condition. We salvaged a limited number of existing slates from stripping and used 26,000 new Welsh Penrhyn Heather Blue slates due to the existing slate being reused many times limiting its angle of creep.

Airtrak Ventilation Systems was used on parapet abutments, eave and ridge ventilation to complete a fully ventilated cold roof. Welsh Penryhn slate was fixed at 110-112mm headlap with copper nails. Prior to laying all slates were sorted and graded to ensure correct sizing.

Project Management:

Our team worked closely with the architect, engineers and the client. Each has significant input in design and finishes. The clients work was to manage our progress and move pupils and guests to varying locations and bedrooms, to avoid being under a significant work area.

Our engineer worked closely with the client and scaffold engineers to double check every load and possible failure to design, prior to proceeding. Our rooflight tolerance was 2mm measured with lasers, to ensure we did not damage the ornate ceiling in the stairwell. Every possible detail was checked and was critical to protect with beautiful building fabric.

Complexity:

Due to the structure of the building being Grade II listed, we were not allowed to fix scaffold ties to the building. The scaffold was 100m long and had a roof spanning 50m, one of the largest free-standing scaffolds in the UK at the time.

To overcome wind load we use Kentledge in some areas of the phase but the only way we could engineer a successful structure was to install 14m deep piles and clamp steel girders to the base, ensuring no uplift. Our wind contingency plan was monitored 24/7 using an anemometer at high level. It took 18 designs to finally achieve structural stability!

Each of the 39 roofs varied in pitch and condition. We salvaged a limited number of existing slates from stripping and used 26,000 new Welsh Penrhyn Heather Blue slates due to the existing slate being reused many times limiting its angle of creep. A vast number of structural repairs were required, with over 1,000 architects’ instructions to date. As you would expect hot works was severely restricted and monitored. Due to lack of ventilation, every area of leadwork had severe carbonation. Working with the Lead Sheet Association (LSA) and Lead Contractors Association (LCA), we were able to design out this issue for the building’s future. Internally, fire breaks and firestopping were installed in every roof.

Workmanship:

Our teams worked closely with the architects and engineers to repair the structure. We then worked with the LSA and LCA to install leadwork to an excellent standard, carrying the Lead Contractor 25 Year Guarantee.

All lead was coated with a stained chalk emulsion which protected the lead from carbonation. Our site agent and deputy were in daily contact with the client. In our view, we think the client did not realise the enormity of the task until we took all the college staff on a roof tour. I think then we can safely say we exceeded every expectation.

Training, Assessment and New Technologies:

With all our tiling, slating and leadwork teams, we have operatives training to various levels of NVQ including Heritage work. Our stonemasons also had trainees on site. We also provide site tours for over 200 people to view and discuss the works at roof level. We also guided trainee architects, to help them understand ventilation requirements, carbonation and natural slate.

Many people on the tour were learning at the college, including pupils learning natural slate work. All of the products used were chosen to enhance ventilation, provide long term durability and not compromise the Heritage building or listed building consent.

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