WELSH SLATE REROOF REQUIRES ONE OF THE LARGEST FREESTANDING SCAFFOLDS
26 September 2021
Work has drawn to a close on the two-year refurbishment of the roof of a historic arts college that required 26,000 new Welsh slates for 39 separate roof areas.
The £4.8 million project won specialist contractor Clarke Roofing Southern Ltd a place in the history books, for the fact it required one of the largest, free-standing scaffolds in the UK at the time, as well as a finalist’s place in the 2020 Pitched Roofing Awards.
West Dean College of Arts and Conservation in Chichester, West Sussex, has an international reputation for excellence in arts and conservation education, from short course to degree level, including professional development courses in building conservation.
But the 126-year-old roof of its home in West Dean House, a Grade II listed building of cultural and historical significance, which also houses the unique West Dean Collection and Edward James Archive, required extensive repairs to all 39 sections, including leadwork, flintwork and carpentry.
The work to repair numerous leaks and failed masonry at high level to provide a fully-ventilated contemporary cold roof had to be carried out in two stages – Phase 1 starting at the west end of the house, moving towards the centre, and Phase 2 working from the centre to the east end, stopping at the workshops.
Each of the 39 areas varied in pitch and condition but Clarke Roofing Southern managed to salvage a limited number of the existing Penrhyn Heather Blues from Welsh Slate which had been re-fixed many times, limiting their re-use due to the angle of creep.
The 26,000 new 500mm by 300mm Penrhyn Heather Blues used to make up the difference were fixed at 110-125mm headlap with copper nails. Prior to installing, all the slates were sorted and graded to ensure correct fixing in accordance with BS 5534 and BS 8000 – the codes of practice for slating and tiling.
The team from Clarke Roofing Southern worked closely with the architect, engineers and college, each of whom had significant input into the design and finishes. The college managed the progress by moving students and guests to varying locations and bedrooms to avoid being under a significant work area.
The building’s Grade II listing and Wyatt flint façade meant Clarke Roofing Southern Ltd could not fix scaffold ties to the fabric. At 100m long and with a roof spanning 50m, it was one of the largest free-standing scaffolds in the UK at the time.
Rooflight tolerance was 2mm, measured with lasers, to ensure the ornate ceiling in the stairwell was not damaged. The vast number of structural repairs required necessitated more than 1,000 architects’ instructions.
Clarke Roofing Southern’s managing director Frank Clarke said:
“In our view, we think the trust, residents and staff 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.”
The contractor also provided site tours for more than 200 people to view and discuss the works at roof level, and guided trainee architects to help them understand natural slate, ventilation requirements and lead carbonation. People on these tours included college students, some of whom were learning natural slate work as part of their course.
All the materials used were chosen to provide long-term durability (with Welsh Slate guaranteed for 100 years) and not compromise the heritage building or listed building consent as well as to enhance ventilation.
The slating, tiling and leadwork teams from Clarke Roofing Southern included operatives training to various NVQ levels, including specific heritage work. It won a place in the finals of the 2020 Pitched Roofing Awards, in the category “Best use of a roof tile for a heritage roof”.
Sean Wootten, Welsh Slate’s technical sales manager for south-east England, said:
“It is always a pleasure to see our fantastic slates installed by high-class professionals on wonderful projects like this. We worked closely with the contractor on the technical details ensuring the slates were supplied at the correct headlap for the project location.”
West Dean College of Arts and Conservation is housed in the turreted and castellated former home of poet, artist, designer and patron of the Surrealist Movement Edward James. Programmes include short courses in arts, craft and building conservation, as well as degree and diploma study in arts and conservation. It is part of The Edward James Foundation, a registered charity which also comprises West Dean Gardens, West Dean Estate and West Dean Tapestry Studios.
To watch Clarke Roofing’s three-minute drone video of the project, please go to https://www.youtube.com/watch?v=Y5EKtX2UAJQ&t=5s.
