RAAC: what can a surveyor do?

What is RAAC?

This acronym stands for Reinforced Autoclaved Aerated Concrete. As the name suggests, the material is like familiar concrete but with bubbles created in its development through a chemical reaction. The constitution of RAAC is a mix of concrete, slag and aluminium, with steel rods set into it for greater strength.

Because of the bubbles within it, RAAC is very much lighter than standard concrete. In the 1950s, with the building boom to cope with the ravages from the bombing raids during the Second World War the previous decade, RAAC was viewed as a wonder material, since it was cheaper than concrete and could be used to put up buildings far quicker. And its use continued for another forty or so years.

Often, RAAC would be used to create long planks that were then fitted together primarily in the construction of roofs, and occasionally walls in numerous buildings.

Why is it no longer the “wonder material”?

The problem with RAAC is precisely down to the design that made it such a popular choice in putting buildings up quickly - the aeration or bubbles.

While the structure of the material was safe enough at the time of putting up all these buildings, it was known that it only had a life of approximately thirty years because of its shortened durability. Naturally, the result of this is that those same buildings, without any remedial action, are past the point of RAAC's expected lifespan.

In addition, RAAC is susceptible to water damage. When it rains, the moisture infiltrates the bubble structure of the aerated concrete and begins the process of increased decay, ultimately making it crumbly and friable. Where there is reinforcement of the structure with steel rods, the water reacts and rusts them away, making the ceiling, beams, floors, walls - wherever the material has been used - at risk of collapse.

Again, this was known early and often the solution was to cover the RAAC with protective materials, such as bituminous paint, but this also has a short lifespan and is subject to its own problems with decay.

What action is being taken?

The government has promised to fund “whatever it takes” to get the closed schools and classrooms up and running again, while headteachers organise the staff to find suitable temporary accommodation or return to home schooling.

There are calls from several quarters for an action plan to assess all affected buildings, but, at the time of writing, this has yet to be developed and reported.

In the meantime, assessors are looking at these problem buildings and recommending what action should be taken. This could be as simple as bracing the ceilings with steel props, or the more expensive option of replacing the RAAC with something more durable and long-lasting.

Is it limited to schools?

Unfortunately not. 

Inevitably, as the emergency has deepened and the government has forced the closure of some 150 or so schools right at the start of term, the disruption will naturally steal the headlines.

However, in the last few days, reports of other areas of society impacted have also been reported, impacting governmental and municipal buildings, which have had RAAC ceilings, beams and walls installed in their construction. 

It is perhaps hospitals - with over 30 possible locations already identified - that is of equal concern, with the already strained resources and bloated waiting lists potentially impacted should parts of the structures need to be vacated and closed.

What is making the process more difficult for the authorities is that there is no register of where RAAC was used in the construction of these buildings. It's therefore a piecemeal process of looking at the risk on a case-by-case basis and verifying the existence of the material before making a judgment on the next steps.

And, even for the homeowner and the commercial property owner, it is a source of potential concern, because it is not clear how many buildings (other than those in the municipal area) are impacted by this crisis. 

What does a Chartered Surveyor do?

A qualified surveyor will be aware of all types of building materials used in the construction of a property, including RAAC.

As new edicts arise from the government or other authorities about a new or existing material, they will have a wealth of knowledge to draw on from the Royal Institution of Chartered Surveyors (RICS) and the Institution of Structural Engineers (ISE), amongst other venerable bodies and institutions. This information will be regularly updated and communicated to the surveyors and their firms.

If you are planning on buying a new home or commercial building, and you are at all concerned about the existence of RAAC or any other problematic materials such as asbestos, you can order a  RICS Level 2 Survey (or HomeBuyers Report), or a RICS Level 3 Survey RICS Level 3 Survey (or Building Survey). 

The Building Survey is the more detailed of the two types of survey, but both will provide a traffic-light rated presentation of the problems and areas of risk for ease of understanding about the overall state of the building's structure.

No doubt, this is all quite a concern, and you may be worried about the cost of such processes to identify whether your planned purchase is in a reasonable state or not, and particularly if your finances are tight.