Dumbarton Sheriff Court flaws needed urgent £2.8m repair job

Urgent repair work and an exclusion zone was ordered as tests uncovered large, empty voids in walls, with coping stones balanced precariously above staff and the public and crumbling, loose mortar.

A massive £12million refurbishment of the 19th century building between 2007 and 2009 saw extensive structural work and a modern extension added.

But in November 2017, a “significant bulge” was found in the south-west corner of the building, outside court 6.

Since then, another £2.8m has been spent to keep Dumbarton’s second-oldest building open.

In a report released under Freedom of Information legislation, structural and civil engineering consultants Will Rudd Davidson stated: “It was found that the original external stone had previously been taken down and replaced with new stone. However, the replacement stone was found not to be constructed monolithically with the remainder of the wall, nor tied back to it, and this had led to it bulging significantly from the line of the existing wall.”

When they started their assessment, stonework was “easily removed due to the weak nature of the mortar”.

Original facing stones were 200mm thick and replaced with ones half the size. There was an even larger cavity on the first floor, “weakening the wall”.

With “no ties” from the outer stones to the primary wall, engineers said it had to be taken down and rebuilt. Any voids were blocked up and filled, mostly with brickwork and with ties at regular spaces.

When nine tonnes of masonry fell at Oxgangs Primary in Edinburgh in 2016, experts found not enough wall ties and the wrong type of ties were used.

Dumbarton Sheriff Court walls showed no ties at all.

As inspectors were taking down the outer wall, the mortar was also found to be “notably weak and disintegrated easily”.

In some cases, masonry was sitting dry, with no mortar, said the report.

Copestones at the top of walls had to be replaced in some cases because of how they were sitting.

Engineers then turned to the north of the building and found stones sticking out 3cm beyond the outer face of the wall.

Again, thinner facing stone had been installed previously and filled with loose dry material and no wall ties.

The report stated: “Due to the concern over the movement recorded, an exclusion zone beneath the area below was created with Heras fencing with immediate effect. This exclusion zone remained in place until the scaffold was erected for the remedial works to the wall.”

At the back of the building, despite it being a new extension just a decade old, “concern over workmanship generally” along with the degrading mortar prompted checks there.

Windposts - to help stability of walls - appeared to have been there during construction but, when inspected 10 years later, were found to have been cut down.

The previous work was led by building firm Rok, which collapsed in 2010. The Scottish Courts and Tribunals Service (SCTS) insisted problems couldn’t be attributed to one company.

The SCTS said: “The building was constructed in 1824 and is built on silt, which together with building techniques at that time, makes it susceptible to ground movement. This has created ongoing stonework and mortar issues and the requirement for repairs throughout its life.

“In general, reference to workmanship in the report refers to a range of work undertaken over a long period of the building’s life and cannot necessarily be attributed to any individual company.

“The current refurbishment was triggered as a result of a routine maintenance inspection when it was noted that there were signs of minor movement in the gable wall. This was resolved but it prompted the SCTS to commission further investigation into the condition of the whole building.

“This highlighted the extent of the issues detailed. We carried out many of the remedial works identified under clear guidance from the structural engineer, so at no time were there any safety issues as a result of the building condition, nor was court business affected.

“With the approval of our estates committee we have carried out the works needed to overcome the structural and maintenance issues identified and ensure the building meets our building maintenance conditions and the standards we require to support Dumbarton Sheriff Court and its users in the longer term.”

Andrew Billingham, a forensic structural engineer, chartered surveyor and expert witness, examined the report into the court.

He said the building was rare for having wood roof trusses running its full length, from north to south.

Parts of the building were settling at different rates and degrees when it was surveyed in 1988 - called differential movement.

That also flagged up that the court was not in good repair - but was not dangerous. Numerous areas of stonework were badly eroded. There was also bad woodworm damage in the roof.

Surveyors said the soil was so bad it was surprising the building hadn’t deteriorated further.

Parts of the building were bulging then.

The 1988 survey also recommended the existing structure be left unaltered going forward to prevent any more movement of the building.

But Mr Billingham noted there appeared to be no mention of original ties between the outer and inner skins of the walls. It was unclear if they existed and have eroded or disintegrated with time.

Ties were recommended for the walls in 1988.

Filling the wall cavities could make the walls heavier and cause further problems as the court settles.

Because there doesn’t appear to be any original measurements - plumb dimensions - taken, it is harder to know from monitoring how much movement there’s been in nearly two centuries.

He said: “It’s a sad building. It suffers from years of lack of maintenance. The bulging might have been right from the outset.

“The building is constructed with dubious quality mortar, that in itself has caused some of the movement.

“You need precise levelling every six months - precise levelling is one way to get peace of mind to whether the building is moving.

“My advice would be to look after it.

“A building today has a design life of 50-60 years. But of course thousands of buildings have lasted longer. But they have to be well maintained to survive.

“This is a high maintenance building, particularly because it’s sitting in the ground and moving differentially. That’s why it’s so important to monitor.”

Monitoring would cost about £2,000 to set up and perhaps £250 every six months, added Mr Billingham.

A spokesman for the SCTS told the Post they were satisfied the “legacy defects” have been addressed.

He said: “A clerk of works was responsible for overseeing the work undertaken by Rok in 2008.

“Dumbarton Sheriff Court, because of its construction and having foundations on silt make it susceptible to stonework defects.

“Investigations did reveal concerns about earlier repairs and their efficacy. The important issue is that with the remedial works instructed this historic B Listed building remains safe and suitable for the court users at Dumbarton for the long term.”

The repair work is expected to be completed in October.

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History:

The building’s central section was built in 1824 and opened as Dunbartonshire County Buildings and Court House.

Around 1826, a jail was built at the rear, which soon got a reputation for prisoners escaping through the roof.

The last public execution was carried out in front of the prison in 1861, when Patrick Lumnay was hanged for killing a friend in Alexandria.

After public hangings were outlawed, Bonhill man David Wardlaw was hanged inside the cells for the murder of his wife.

Child prisoners as young as 11 were held there, with one case of a 12-year-old boy sentenced to 18 months for stealing a watch.

As well as being taught to read and write, prisoners were employed to make door mats, nets and do sewing.

The jail was closed in 1883 and most of it was demolished to make room for the A814.

The town council moved into the structure in 1862 when it was extended with flanking wings. And the police moved in after a further expansion in 1898.