RAAC roof panels: what commercial building owners should check
Updated 23 October 2026 · SEO Dons Editorial
What is RAAC, and why does it matter on a commercial roof?
Reinforced autoclaved aerated concrete is a lightweight form of precast concrete. HSE describes it as commonly used in UK buildings between the mid-1960s and the mid-1980s and mainly found in roofs, with occasional use in floors and walls. It is less durable than traditional concrete, and HSE says the problems that followed could have significant safety consequences.
For anyone planning roof work, the difficulty is that the planks are hard to see. The Institution of Structural Engineers (IStructE) says flat roof panels are often difficult to access, and so difficult to survey, maintain and replace, partly because of sub-ceiling structures, services, suspended ceilings, finishes and the external roof membrane. This guide makes no statement about the condition of a particular roof; only a structural engineer’s assessment can do that.
Which buildings could contain RAAC, and which guidance applies?
The sources give different date ranges, so use a range as a prompt to check records, not to rule a building out.
| Source | Period and location given | Written for |
|---|---|---|
| HSE | Mid-1960s to mid-1980s; mainly roofs, occasionally floors and walls | Anyone with a legal duty to manage buildings |
| IStructE | Mid-1950s to mid-1990s; roof planks, wall panels and sometimes floor planks | Building owners and managers |
| Department for Education (DfE) | Buildings constructed or modified between the 1950s and 1990; floors, walls and roofs, pitched and flat | State-funded education estates in England |
DfE’s identification guidance is non-statutory and written for state-funded education estates in England, so a warehouse, office, retail or industrial owner is outside its scope. For other building types HSE points to the IStructE’s guidance, and this guide follows that route. DfE’s “constructed or modified” wording is a reminder that a later extension or refurbishment of an older building belongs in the same check, and IStructE adds that not every building from the period will have RAAC.
Who has to check?
HSE’s guidance is for the “dutyholder”: the building owner, the landlord for the premises, or the person or organisation with clear responsibility for the building’s maintenance or repair. Under a lease that can be the landlord, a tenant with a repairing obligation, or each for different parts. The dilapidations guide and the guide to who pays for a commercial roof cover the lease side.
HSE says anyone responsible for the management, maintenance or alteration of buildings should first establish whether they contain RAAC and then take steps to manage and control the risk. A re-roof is maintenance or alteration work, so the question belongs before design.
How do owners find out whether a roof has RAAC?
IStructE sets out three steps: identification, assessment and solutions. For the first, it says an experienced estate or maintenance manager, or the building owner, can carry out identification, and that anyone unsure can contact a professionally registered structural engineer or surveyor. For a building from the affected period whose construction is unclear, IStructE advises an inspection and a risk assessment.
Start with the paperwork: drawings, specifications, structural reports and earlier surveys. The deck types guide summarises the visible clues from DfE’s identification guidance, and the roof survey guide explains survey methods, though on a suspected plank deck any core cut is for the engineer to specify.
Two cautions apply before anyone looks more closely. First, HSE warns that if asbestos is also present, a collapse or remediation activity related to RAAC could disturb it, and that asbestos information must be shared with anyone liable to disturb it, such as contractors. Check the asbestos register before a ceiling is opened. Second, IStructE’s FAQ records a roof panel at one school spalling while workmen were drilling into it to install light fittings, and sections of a panel at another school failing while builders’ work was being carried out. Those are reasons to keep drilling, coring and fixing away from a suspected deck until an engineer has agreed the method.
Why do roof leaks and added loads matter for RAAC planks?
Both feature in IStructE’s account of how planks deteriorate. The panels are porous, and if water gets in they can deflect further. Water can also corrode the reinforcement, which can make the material spall and break apart. IStructE adds that water ingress can add dead weight and weaken the aerated concrete, and that RAAC should perform comparably with similar materials when appropriately maintained, with “no overloading and managing water ingress” as examples.
The other mechanism is bearing. IStructE says panels with insufficient bearing and compromised structural integrity can collapse with little or no warning. That may occur where the internal reinforcement stopped short of the load-bearing point, which it describes as difficult to detect without intrusive investigation. It says the bearings should be inspected and measured, which is an engineer’s task, not a roofer’s.
In practice, a history of leaks is information the engineer will want, and anything that adds weight, such as ballast for a single-ply system, new plant, a solar array or stored materials, is a loading question for the engineer before it is a roofing detail. The solar panels guide covers loading for PV.
What is the roofing rule on a suspected RAAC deck?
The rule below is this guide’s own summary of what HSE, IStructE and the roofing trade body NFRC say together. It is not a quotation from any of them.
Do not strip, overlay, add ballast or plant to, or fix into a roof you suspect has RAAC planks until a structural engineer has assessed it.
The reasons are in the sources. HSE says that if RAAC planks are confirmed or suspected, the owner should seek guidance from a competent structural engineer to assess them and develop a management plan. IStructE says their structural condition will need to be determined by a Chartered or Incorporated Structural Engineer. The National Federation of Roofing Contractors (NFRC) publishes a safety alert on the approach contractors should adopt if they suspect RAAC planks on a flat roof refurbishment, so a contractor can be asked how it applies that alert.
The sequence the rule implies:
- Identify. Check the records; if unsure, bring in a structural engineer or surveyor.
- Assess. A structural engineer determines the condition of the planks, including their bearings, and whether any immediate temporary remedial work is needed.
- Decide. On the engineer’s findings: monitoring, propping, strengthening, or removal and replacement.
- Specify. Only then design the roof build-up, loads and access. The repair or replace guide covers the roof-level decision.
- Pass it on. Put the findings in the pre-construction information given to every designer and contractor, and check that the construction phase plan reflects the deck and any asbestos.
What do investigation and remediation involve?
IStructE’s guidance comes in two parts: a March 2022 note on investigation and assessment, and an April 2023 report on the critical risk factors in RAAC panel construction and how they may affect remediation and management. HSE directs owners to sections 5 and 6 of the further guidance. It is written for structural engineers, who apply it case by case.
Depending on the engineer’s findings, IStructE says ongoing monitoring, remedial propping or strengthening may be needed, and in some instances planks may need to be removed or replaced. It also says remedial systems should be subject to regulatory approval, such as building control, with proprietary systems assessed by a technical approval body as appropriate. The building control routes guide explains the routes for a re-roof. If the outcome is a new deck and roof, the job becomes a re-roof with its own CDM roles, as the CDM 2015 guide sets out.
If you want to talk a roof project through, you can send an enquiry through the form on this site.
Sources
- Managing risk from reinforced autoclaved aerated concrete (RAAC), Health and Safety Executive, checked 22 October 2026
- Reinforced Autoclaved Aerated Concrete (RAAC), The Institution of Structural Engineers, checked 22 October 2026
- IStructE statement & FAQs: Reinforced Autoclaved Aerated Concrete (RAAC) (25 October 2023), The Institution of Structural Engineers, checked 22 October 2026
- RAAC Investigation and Assessment – Further Guidance (17 April 2023), The Institution of Structural Engineers, checked 22 October 2026
- Reinforced autoclaved aerated concrete: identification guidance (last updated 20 July 2026), Department for Education, GOV.UK, checked 22 October 2026
- RAAC: NFRC Safety Alert (4 September 2023), National Federation of Roofing Contractors, checked 22 October 2026
Common questions
Is RAAC banned in the UK?
The HSE and IStructE guidance used here sets out duties and an assessment process rather than a ban. IStructE says RAAC is still manufactured and installed in many parts of the world and that, as far as it knows, UK use declined in the 1990s.
Can RAAC planks be repaired?
That depends on the structural engineer’s findings. IStructE says ongoing monitoring, remedial propping or strengthening may be needed and, in some instances, planks may need to be removed or replaced. It adds that remedial systems should be subject to regulatory approval, such as building control.
Can a roofing contractor tell me whether my deck is RAAC?
IStructE’s steps name an experienced estate or maintenance manager, the owner, or a professionally registered structural engineer or surveyor for identification. Contractors have their own route: NFRC publishes a safety alert on what to do if they suspect planks on a flat roof refurbishment. Whatever the route, HSE says confirmed or suspected planks go to a competent structural engineer for assessment.
Does the schools guidance apply to my warehouse or office?
No. DfE describes its guidance as non-statutory and for responsible bodies of state-funded education estates in England. For other buildings HSE directs dutyholders to the IStructE’s guidance, which is where this guide takes its lead.