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Welsh Slate helps a historic railway station get back online
Historic Wingfield Station reroof with Welsh Slate starred on TV.
One of the earliest surviving railway stations in the world is enjoying a new lease of life, and TV stardom, thanks in part to Welsh Slate.
Some 4,200 or 230m2of Welsh Slate's Penrhyn Heather Blue roofing slates have replaced their 180-year-old predecessors on the roofs of the main station and parcel shed buildings at Wingfield Station in Alfreton, Derbyshire.
The Grade II* listed station, which was built in 1840, is the sole survivor of railway architect Francis Thompson's notable sequence of picturesque stations between Derby and Leeds, widely regarded as his finest work. One of the earliest railway stations in England, it closed in 1967 and fell into disrepair.
After more than 30 years of deterioration, it was compulsory purchased by Amber Valley Borough Council, before the Derbyshire Historic Buildings Trust (DHBT) took over ownership in 2019.
A first, £470,000 phase of urgent works, which required specially-designed scaffolding during night-time possessions of the Midland main line, is now complete after nine months, and was marked by an appearance on Yesterday UKTV's "The architecture the railways built" as DHBT's flagship project. This was funded by an Historic England grant and carried out over six months by ASBC Conservation and Heritage Specialists.
A second phase of non-urgent works is due to start early 2023, with full completion by the summer. The main station building will be leased to small office users and open a set number of days a year for the public to appreciate its international significance.
Derbyshire-based James Boon Architects developed a conservation philosophy for the site next to Network Rail's main line, in conjunction with the DHBT, Historic England and other stakeholders.
This stipulated that the original or primary fabric related to the pioneer phase of the original station building, among other factors, should be considered sacrosanct and its loss to be avoided unless strong justification can be established.
In addition, the external and internal appearance is to be restored to that of the pioneering phase, and repairs to original fabric are ‘like for like' materials or informed by evidence on site to be restored to their original materials and appearance.
In terms of the roof, it was inspected for evidence of nail holes to inform the size of the graduations originally on it. Roofing specialists appointed by Historic England established what size slates were on the roof and which were fixed previously, along with the methods of fixing, including any indication of underlay. It was identified that slates were nailed to the sarking boards over rafters.
The spacing of the slate nails on the ticket office, which had a roof pitch of 19°, was measured at each course. These varied slightly because the nail holes were made by hand and were not precisely placed, and to be secure, the slate nails should not have been driven near to gaps in the boarding. Typically, they would be at least half an inch away from the board's edge. Therefore, the measurements were averaged, and probable slate lengths determined.
The high-level roof over the booking hall, which had a pitch of 20°, was slated with the slates centre-nailed directly to the boards with two 1.5inch copper nails. There was no underlay over the boards.
The examination of the slate nailing indicated that, apart from repairs, the boarding had only been slated once. The slate lengths and widths were measured and found to be 22.1/4" x 11.1/4", which suggested they were from Welsh Slate's Penrhyn Quarry which traditionally made slates a ¼ inch oversized.
The original slates and head laps did not conform to BS 5534 recommendations, but this was overcome by using larger slates at larger head laps as it was important to conserve as far as possible the margin or the visible area of the slates to achieve the original appearance of the slate roof. The effective width of the centre-nailed slates is reduced by the distance of the nail holes from the long edges of the slates, typically this would be about an inch.
Extra nails were used (four nails per slate at holing gauges of 450mm and 550mm) to compensate for the reduced uplift resistance on nailing higher in the slates. Wind uplift is also proportional to the slates' thickness.
All abutments were laid with a lead soaker interleafed with each course of slate and covered with a flashing which has a straight cut joint into the stonework. The original line of the eaves slates came over the 3"x1" arris cut tilt fillet, allowing for a 4" overhang into the lead gutters.
James Boon said: "Other than the historic and listed nature of the building, the main requirement related to the proximity to the adjacent mainline railway line. With limited future access to the trackside for maintenance, initial proposals looked at the possibility of other roofing finishes to that side that wouldn't require maintenance.
"However, after the detailed studies of the history of the roof, it was apparent that apart from the significant roof damage following the theft of the lead gutters, much of the rest of the roof was in decent condition and would be able to withstand the conditions of high speed trains passing by, without concerns for this damaging slates. The only concession to concerns regarding uplift from passing trains was using additional nail fixings.
"The Welsh Slate played an important part in the project as it allowed us to reinstate the original material. It was important to us that re-slating could be achieved on a like-for-like basis.The fact that a like-for-like repair enabled us to go back to the original supplier, plus any associated sustainability benefits of using a UK-supplied material, were both an added bonus, andalso helped us to fulfil the aims set out in the conservation philosophy at the start of the project."
ENDS
Photos: Derbyshire Historic Buildings Trust and ASBC Conservation and Heritage Specialists.