Historic Tunsgate Arch’s Renovation Work Is Revealed

Published on: 15 Aug, 2019
Updated on: 15 Aug, 2019

By Hugh Coakley

Following the fall of a piece of stonework from Tunsgate Arch in February this year (2019), The Guildford Dragon NEWS has been given exclusive access to the repair works, revealing the surprisingly good condition of the structure.

Two sections of stone missing from the central section of Tunsgate Arch. Click on the photo to enlarge it in a new window. The piece on the left had fallen from the arch prompting the repair project and the other had been removed as a precaution.

The dislodged masonry was the result of tiny movements of the stone portal over time but “the good news,” said Alistair Piper, consulting structural engineer of Cooper & Withycombe, “is that the structure is in good shape.”

The guilty parties. The errant masonry which had prompted the repair project on Tunsgate Arch.

The falling masonry had required Tunsgate Arch to be partially closed to pedestrians and prompted an investigation into the causes. A second piece of stone was removed as a precaution after cracks were observed.

The Grade II listed structure, built in 1818, was radically altered in 1933 when the two central columns were moved apart to allow traffic, including buses, to pass through along Tunsgate.

Three steel beams behind the Portland stone facade support the coat of arms pediment and the stone portal below it as well. The inside of the steel beams were inspected by borescope with the entry hole on the beam visible as a shiny patch.

This was done by inserting three steel beams, joined together by riveted steel plates at the top and bottom, to provide a new support for the widened arch.

The steel beams supported the weight of the classical pediment above with Guildford’s coat of arms, that includes features each side relating to the use of the structure as a corn market and court house. The stone beam, which had originally been resting on the columns, was hung by four steel rods from the steel beams.

The stone beam, which had been originally supported on the stone columns, is held up by four steel rods hanging from the steel beam. The hanging rods will be replaced with stainless steel. The wooden prop is temporary.

Rob Kember, the site manager for the specialist stone and restoration company, PAYE, said: “You don’t know what you are facing when you open up a structure like this. It can be slow work.

“Apart from the main repairs, we have also taken out about 25 small patches which will be replaced with Portland stone. All minor repairs are carried out using a lime and Portland stone dust mix to match in with the existing stone.”

1936 drawing showing the three steel beams and the hanging steel rod arrangement.

Part of a drawing showing the columns moved apart, the steel beams (coloured blue) installed and the internal brick arch partially removed. The drawing is dated 1936 even though the Grade II listing says that the “front columns re-sited in 1933.”

The weather was very wet on Wednesday (August 14) when I visited. Stonemason James Smith said: “It is a lovely job when the weather is good. Seeing the steel come into view when we opened it up was interesting. The hanging rod system looks like a practical detail; it has worked well.”

James, 28, has worked as a stonemason for 12 years with 10 years working with PAYE, including working on St James’s Palace, the Magna Carta monument in Runnymede and St John’s Church in Guildford.

Team effort on Tunsgate Arch repairs. From the left, stonemason James Smith, PAYE site manager Rob Kember, and chartered surveyor Mark Graham.

Alistair Piper said that deciding what the best way to carry out the repair was a “team effort,” and: “It is important to use all the specialist knowledge available when working on these heritage buildings.”

With the scaffolding in place, Guildford Borough Council is taking the opportunity to carry out essential maintenance work on the structure. This has included fitting lead sheeting to replace the leaking roof area, repairing some rotten wooden pieces in the area behind the portal, cleaning the stone facing and replacing the pigeon deterrent spikes on the coat of arms with unobtrusive netting.

A Dennis Loline 357 bus emerging from Tunsgate Arch. Buses did not pass through the arch on scheduled routes. The photo was a mock-up taken early one Sunday morning before the High Street was part-pedestrianised and Tunsgate closed to traffic. Photo courtesy of Peter Trevaskis – Aldershot & District Bus Interest Group.

Building surveyor Mark Graham, working with heritage property for Guildford Borough Council, said: “We will be adding hatches to the rear of the beams to make future inspections much easier. GBC will be introducing an asset management system for all its structures. Ideally for these heritage structures, it should be inspected every five years.

“This was very much an unscheduled project. Because of the cost, we have had to defer some work, mostly redecoration, on the Guildhall which was programmed for this year.”

The cost of the works on Tunsgate Arch is £115k and a large part of that cost has been for the access scaffolding which is a structure in its own right. It had to be strong enough to temporarily carry the full weight of the portal and it had to stand alone without being tied into the Grade II listed arch. “It was complex and had to be specially designed.” said Alistair Piper.

With between six to eight weeks for the replacement Portland stones to be selected, quarried and cut, the works are due to be completed on September 20.

View from the top of the scaffolding down the High Street on a rainy day.

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