Professional RAAC roofing contractors for schools

What is RAAC, and how do you identify a RAAC roof?

From structural integrity to health and safety compliance, Acclaim Contracts Ltd are professional RAAC roofing contractors working with schools and companies throughout the south east.

What is RACC?

RAAC, or Reinforced Autoclaved Aerated Concrete, stands as a variant of lightweight concrete enhanced with steel reinforcements. Created in Sweden during the 1920s, Autoclaved Aerated Concrete (AAC) emerged as a revolutionary alternative to conventional concrete mixes, providing a notably lighter option.

A concrete crisis

Regrettably, the structural integrity of RAAC suffered as a consequence of its lightweight characteristics. Dissimilar to conventional reinforced concrete, RAAC exhibits heightened susceptibility to deflection. The porous composition of reinforced steel renders it more susceptible to corrosion, thus necessitating a safeguarding layer of latex cement or bitumen. Additionally, the ACC inadequately adheres to the reinforcement steel, mandating the utilisation of welded crossbars to firmly secure it.

The structural strength of RAAC was compromised in order to achieve its lightweight nature. Unlike traditional reinforced concrete, RAAC lacks the same performance and tends to exhibit greater deflection. As a result, the RAAC roof planks installed in the 1960s started experiencing failures by the 1980s.

Is RACC unsafe?

During the latter part of 2018, both the Local Government Association (LGA) and the Department for Education (DfE) issued an urgent notification to all owners of school buildings. The purpose was to inform them about an incident at an Essex school where a section of the flat roof, constructed using RAAC roof planks, experienced a sudden collapse, catching everyone off guard. Thankfully, this event took place over the weekend when the building was not in use.

How to identify a RAAC roof in your school

In case you have doubts about possessing a RAAC roof, the Standing Committee on Structural Safety (SCOSS) has gathered a list of indicators to help you identify potential hazards and ascertain whether your roof is in imminent danger of collapsing.

• If ponding can be seen on the roof, or the roof has recently leaked or is leaking, then there is cause for concern. This could point to the RAAC planks deflecting and damaging the existing roof waterproofing, causing leaking or allowing the waterproofing to deflect with the planks, causing ponding. The water ingress itself can exacerbate the failure of the RAAC planks.
• The roof has had additional load subjected to it by new waterproofing overlays, plant or equipment. This also raises concerns that the design load of the planks has been exceeded and could lead to catastrophic failure.
• If a new waterproofing overlay has been installed and has a black finish replacing a previous more reflective overlay, this is of particular concern as increased thermal heating may increase the risk of RAAC failure.
• If underside deflection can be seen, or cracking observed towards the end of the planks, the area should not be inhabited, as the roof structure cannot be deemed secure and needs to be removed by a professional contractor.

Determining whether your roof deck is built with RAAC can be a challenging task due to the absence of a centralised register for buildings using RAAC roof planks. However, it is advisable for owners or building managers to engage the services of a skilled structural engineer or building surveyor to conduct a thorough physical examination. By doing so, one can effectively evaluate the likelihood of having a RAAC roof deck while ensuring accurate identification of the construction materials employed.

Take action

Immediate action is required of all schools and educational establishments to evaluate their resources, detecting any roofs containing RAAC (Risk Assessment and Action Control) elements. Furthermore, a thorough risk assessment must be conducted promptly, and appropriate measures that might include RAAC roofing remediation should be taken to remove any hazards.

Delivering the highest levels of roofing compliance and safety

Acclaim Contracts are professional, expert RAAC roofing contractors who understand how important creating safe spaces can be. Our team of qualified and experienced roofing experts will ensure that all RAAC roofing replacement work is completed to the highest professional standard, making sure that the structural integrity and health & safety compliance of your building is maintained.