The cause of the fire that ravaged the Glasgow School of Art for a second time may never be known but wilful fire raising and electrical failure cannot be "fully discounted", a long-awaited report has concluded.

The Scottish Fire and Rescue Service (SFRS) has published the findings of its investigation into the 2018 fire that caused catastrophic damage to the prized Mackintosh Building as it neared the end of a £35million restoration project following a previous blaze in May 2014.

It makes a series of recommendations which suggest the masterpiece building could have been better protected.

Fifty per cent of the building was said to be well alight within 38 minutes of the arrival of firefighters.

The investigation is said to have been the most complex and resource-intensive ever undertaken by the SFRS.

Ross Haggart, SFRS Deputy Chief Officer, said that despite intense scrutiny of "every aspect" of the fire, the cause has been recorded as undetermined.

READ MORE: Glasgow School of Art fire: 'We need to learn from report', says leading architect 

The report said accidental ignition by something like a cigarette could not be fully ruled out as well as a deliberate fire or an electrical failure.

Coverage of the entire scaffolding structure was not provided, which suggests that a person, or persons, could have accessed the building via the structure, undetected.

CCTV footage taken from the Sports Complex Building of St Aloysius College, captured a lone figure in the carpark approximately three hours after discovery of the fire. They were never traced by Police Scotland.

The report found that the timeframe concerning this individual did not coincide with the outbreak of fire, however, involvement earlier in wilful fire-raising activity "could not be fully discounted".

HeraldScotland:

The SFRS said it is also possible that the system supplying electricity to the office areas on level 2 could have suffered a fault condition in an unknown location.

Mr Haggart said: "Unfortunately, almost everything within the building was severely damaged or consumed in the fire and that included any potential items of evidence that could have provided those answers.”

Kier Construction Limited was appointed in June 2016 as the main contractor for the restoration project.

The report says lessons should be learned for other  construction projects, particularly those involving building of cultural significance.

It said management teams responsible for delivery of construction or renovation projects, should ensure that, during the early planning stages of the project, they fully consider the risk of fire.

HeraldScotland:

When construction work commences, a comprehensive Fire Risk Assessment (FRA), should identify suitable and sufficient control measures are implemented to mitigate risks.

Consideration should not only be given to protection of life, but also to protection of property at significant risk or of national importance.

The report outlines how the alarm was raised at 11.19pm on Friday, June 15 2018 to reports of fire within the Mac Building on Renfrew Street. 

The neighbouring O2 ABC and other premises were also damaged in the fire.

HeraldScotland:

The first SFRS appliances arrived on scene within six minutes and at its height, more than 120 firefighters worked to contain and then extinguish the fire. 

READ MORE: 'Chilling' 1913 documents uncovered about Mackintosh masterpiece 

There were no casualties and firefighting operations continued for a further 10 days.

The report concludes that it is likely the fire started on the east side on or above level 4 of the Mackintosh Building. 

An unlimited air supply fed through the duct system is said to have intensified the fire, promoting "uncontrolled fire growth and rapid development".

HeraldScotland:

The investigation involved the excavation and physical examination of hundreds of tonnes of fire-damaged debris and careful analysis of witness testimonies, CCTV and photographic footage. 

According to the SFRS it got underway as the fire took hold on June 15, 2018 and continued through to September 30, 2021. 

Gordon Gibb, an architect, and former GSoA lecturer, who read the report ahead of its publication, said: "What I find interesting in the recommendations is that there was a possibility of this not happening and that would be have been that the building which was in its most dangerous phase of its life could have been better protected.

HeraldScotland:

"The report is very clear in that it does not apportion blame but I think the subtext here is that whether it's a combination  of the regulatory process not being sufficient - because it only preserves life and not buildings and there are certain buildings that are more important than others - but also this was a particular building with known vulnerabilities and [it's] whether enough was done to protect that by those who knew what those vulnerabilities were.

"This is not about insurance,it is about preservation of national heritage."

He said he was in favour of strengthening current regulations that govern the protection of buildings of cultural significance.

READ MORE: Muriel Gray steps down as Glasgow School of Art chairwoman 

The report into the 2014 fire, which destroyed the school's library, took less than six months to complete and identified the cause of the blaze as gases from a foam canister used in a student project.

Muriel Gray announced in September last year that she would be stepping down as chairwoman of GSoA.

Last year art school chiefs said rebuilding the Glasgow School of Art's Mackintosh building as a "faithful reinstatement" of the one destroyed by fire three years ago is the preferred option for its future.

HeraldScotland:

Ross Haggart, SFRS Deputy Chief Officer, said: “Our investigation into the devastating fire at the Glasgow School of Art has been a deeply complex and protracted process.

“Due to the nature of the ongoing restoration and construction works combined with other factors such as the air supply into the building, the fire was unfortunately able to take hold, spread and ultimately cause catastrophic damage.

“This presented a number of challenges to our investigation, namely working within a structurally dangerous site to physically examine hundreds of tonnes of debris which was up to four metres in height and heavily compacted.”

 “We are of course acutely aware of the cultural significance of the Mackintosh building and the pressing needs for answers.

“We scrutinised every aspect of this fire to ensure our investigation was as robust and thorough as possible.

"We were unable to find sufficient evidence to support any credible origin and it has not been possible to establish a definitive cause."

"However we have made a number of recommendations including the introduction of new mechanisms to enhance information sharing around ongoing construction projects within Scotland to ensure the safety of our firefighters and our communities.”