RAAC to be removed from Galashiels Fire Station

Crumbling concrete has outlived its lifespan v.1

Potentially dangerous roof panels constructed with lightweight concrete are set to be removed from Galashiels Fire Station.

Reinforced autoclaved aerated concrete (RAAC) is a lightweight material that was used mostly in flat roofing, but also in floors and walls, between the 1950s and 1990s.

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The Health and Safety Executive says RAAC – also present in many school buildings – is now beyond its lifespan and may “collapse with little or no notice”.

Scottish Fire and Rescue confirmed that RAAC is present in buildings at both Galashields and Hawick fire stations.

Now a planning bid has been submitted to Scottish Borders Council for replacement of the crumbling roof panels in both the appliance bay and the gym at Galashiels Fire Station in Croft Street.

In an earlier statement Iain Morris, the Scottish Fire and Rescue Service’s acting director of Asset Management, said: “The safety of our staff is paramount and immediate action was taken as soon as defects to the roof construction were identified in 14 of our sites in 2019.

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“We have in place temporary supports to reinforce areas of the roofing and we have maintained operations from these locations. We will continue to monitor these measures.

“In most cases, the safest and most cost-effective solution is to rebuild.”

RAAC is a cheaper alternative to standard concrete, is quicker to produce and easier to install.

It is aerated, or “bubbly”, like an Aero chocolate bar.

But it is less durable and has a lifespan of around 30 years.

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Its structural behaviour differs significantly from traditional reinforced concrete.

Moreover, it is susceptible to structural failure when exposed to moisture. The bubbles can allow water to enter the material.

If that happens, any reinforcing steel can also decay, rust and weaken.

Because of this, RAAC is often coated with another material, such as bitumen on roofing panels. But this material can also degrade.

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The Standing Committee on Structural Safety (SCOSS) noted that: “Although called ‘concrete’, RAAC is very different from traditional concrete and, because of the way in which it was made, much weaker.”

According to Loughborough University, there are tens of thousands of these structural panels already in use and “many are showing signs of wear and tear and deterioration”.