Reinforced Autoclaved Aerated Concrete (RAAC)

Reinforced Autoclaved Aerated Concrete (RAAC)

Can latent defects be hiding in plain sight? 

 There have been many headlines over the last year in relation to Reinforced Autoclaved Aerated Concrete (RAAC). As we approach the start of the summer holidays, we look back to the start of the school year where the seemingly last-minute identification of RAAC prevented a number of schools nationwide opening to pupils at all. The perceived instability caused a minor outcry as to the state of repair of our public buildings – but it’s not just an issue for publicly-funded buildings, and any structural defects could be a potential headache for private and commercial landlords. 

 What is RAAC? 

RAAC is a lightweight concrete, designed with air bubbles throughout the structure. It is lighter than regular concrete – quicker to fabricate and easier to install. It was mainly used in construction between the 1950s and the 1990s, often in roof covering but also in external render. 

 Why is RAAC a problem? 

Initially, it’s not. But it’s designed to have a lifespan of around 30 years, so many of the buildings which include RAAC are either nearing, or well past, their intended life. The air bubbles within the concrete can become filled with water which can lead to sudden structural failure without warning.  

 Does RAAC pose a general health risk? 

According to the Royal Institute of Chartered Surveyors, no. But equally no one wants to be standing under a concrete roof when it fails without warning. 

 My tenant has a full repairing lease – isn’t this their problem? 

Not necessarily. 

 On a full repairing lease in Scotland, a tenant will undertake to maintain the property in good and substantial or tenantable condition. Their obligations may be limited by a schedule of condition, but since these schedules are generally limited to a visual inspection, they are unlikely to include the presence of RAAC within the excluded obligations. 

 However, at common law, this repairing obligation won’t make the tenant responsible for any extraordinary repairs or for latent and inherent defects, which are the landlord’s responsibility by default. These repairs need to be expressly referred to in the repair clause before liability can transfer to the tenant. 

 Which category does RAAC fall into? 

We’re often told that we don’t need to worry too much about latent defects in older buildings. In general terms, latent (i.e. “hidden”) defects (e.g. design flaws, incorrect construction materials etc.) are often thought to become apparent around seven to 10 years into the life of a building. That is why collateral warranties from contractors on a new-build property are usually drafted to last for 10 or 12 years.  

 There’s also a strong argument that the presence of RAAC doesn’t necessarily constitute an “inherent” defect either. If a building was constructed with materials so as to have a lifespan of 30 years, then there is not necessarily an inherent defect in the design. The problem comes when the building is put to continued use long after its intended lifespan has come to an end, not when it is used as designed. 

 It’s possible that remediation of RAAC might be an “extraordinary repair” (being a repair that is required irrespective of the cause of damage. Usually for a tenant to be responsible for these, the lease will require the tenant to “repair, rebuild, renew and replace” as often as may be necessary – but if the RAAC currently holds good with no structural problem arisen to date, is the repair “necessary” or only advisable in terms of good practice? 

 Should I avoid buying a building if RAAC is present? 

Not necessarily. We recently acted for clients whose pre-purchase surveys found RAAC present on site. The lease didn’t provide for the tenants to take on any of the above liabilities and so following our review of the lease documents, the clients initially aborted the purchase. However, following further discussion with the surveyors, our clients ascertained that the RAAC only affected a small part of the site (which was not critical to the tenant’s business).  

 Our clients were able to re-negotiate the purchase price with a view to reflect the costs of demolition of the affected area in due course. Whilst that won’t be a solution in every case, our clients were able to complete the deal with a positive outcome for all, thanks to early engagement with their professional advisers.  

 Lawyers don’t operate in isolation and Gilson Gray are always happy to work in conjunction with the other members of your team to help you find the best way forward. 

If you would like to learn more about our Real Estate services please view our services here.

Gregor Duthie
Legal Director, Real Estate


Sign up to our News & Insights!