Patented structural replacement
We replace failing RAAC. We do not simply prop it.
EXTEND SYSTEM is a patented telescopic aluminium beam that takes over the load path from a deteriorated RAAC panel. Installed from soffit level, without welding, without hot works, and in most cases without moving anyone out of the building.
Where are you with RAAC?
Select the situation closest to yours.
RAAC has been confirmed in my building
See how the beam takes over the load path, and what functional replacement means for verification.
The building cannot close
Hospitals, schools, civic buildings. See how the system is installed around an occupied programme.
I need figures my engineer can check
Spans, loadings, profiles, certification and the basis of calculation.
A permanent structural solution, delivered without emptying the building
EXTEND SYSTEM was designed in 1992 by architect Josep Maria Vulart to resolve deteriorated concrete beams without demolition. Three decades and thousands of installations later, the same system is being applied to RAAC across the United Kingdom.
Proven in service
Patented in 1993 and installed continuously since, across schools, hospitals, car parks and housing.
A verifiable load path
The beam becomes the load path, so the deteriorated panel above is no longer the element the structure depends on.
Rapid installation
Two or three fitters install 8 to 10 beams a day, around 25 to 30 m², including outside normal hours.
No decant, no hot works
Hand-carried, dry assembly with no welding, bolts or screws. No hot works permit required.
RAAC does not fail gradually. It fails without warning.
Reinforced Autoclaved Aerated Concrete is a lightweight concrete produced by aerating a cement and sand slurry into a matrix of air bubbles, then curing the cast panels under heat and pressure in an autoclave.
That bubble structure is what makes RAAC light and well insulated. It is also what gives water a very large surface area to penetrate. Once moisture reaches the reinforcement cast inside the panel, the steel corrodes and expands, and the panel loses tensile capacity from the inside, where nothing is visible from below.
RAAC panels typically fail in shear rather than bending — a brittle failure mode, with little or no cracking to give warning beforehand. It is the reason a panel that looks acceptable from below can still be at the end of its service life.
How EXTEND SYSTEM works
EXTEND beams are extruded aluminium profiles that assemble telescopically in two or three sections. They are sized to the exact span and locked by friction fit, then fixed to supports that have been verified to carry the load.
Once fitted, the beam becomes the load path. Where the residual contribution of the existing element is assumed to be zero, this constitutes a functional replacement rather than a repair.
The distinction matters for verification. The resulting system can be modelled, calculated and checked as a defined load path, independently of the condition of the material it replaces.
Why it works in occupied buildings
Most RAAC-affected buildings cannot simply close. Hospitals continue treating patients. Schools have six weeks of summer and nothing more. Civic buildings cannot suspend their activity indefinitely.
The characteristics that make the system workable in those conditions are practical rather than theoretical:
- Beams are light enough to be carried by hand — no crane or heavy plant
- They pass through standard doorways and corridors in sections
- Assembly requires no welding, bolts or screws, so no hot works permit is needed
- Installation is dry, quiet and generates minimal dust
- Work can be sequenced bay by bay, and carried out outside normal hours
- Added dead load is a fraction of an equivalent steel solution
Technical summary
| Material | Extruded high-strength aluminium, rectangular sections with variable face |
| Range | Six profiles, combined telescopically |
| Assembly | Two or three telescopic sections; no welds, bolts or screws |
| Spans | Over 7 metres |
| Loading | Above 1,000 kg/m², subject to project-specific verification |
| Installation rate | 8 to 10 beams per day with two or three fitters |
| Lead time | 24 to 48 hours from stock |
| Maintenance | None required; aluminium does not corrode |
| Weight | Approximately one third of an equivalent steel beam |
| In service since | 1992; patented 1993 |
Spans, beam spacings, design loads and support arrangements are verified for each project. Calculations are prepared by our technical department and issued for review by the project engineer.
Certification and testing
Status in Great Britain. CE marking remains recognised for construction products placed on the Great Britain market. In September 2024 the UK Government extended that recognition indefinitely, with a commitment to a minimum two-year transition period should the position change. Our EN 1090-1 certification is therefore directly applicable to UK projects today.
The full certification pack and the calculation basis are available to the project engineer at enquiry stage.
Fire performance
Aluminium is non-combustible and achieves reaction to fire Class A1 under BS EN 13501-1.
Reaction to fire and structural fire resistance are separate questions. Class A1 does not in itself establish that an unprotected beam achieves a given period of fire resistance. Where a specific R rating is required, it is determined by project-specific assessment and, where necessary, an appropriate protection system.
Amendments to Approved Document B taking effect on 2 March 2025 withdrew the BS 476 national classifications for reaction to fire. Only BS EN 13501 classifications are now accepted in England for this purpose.
Case study: school building, Mataró
350 beams, three storeys, one summer holiday
A school with deteriorated floor structure across three storeys, which had to reopen for the start of the academic year.
The calendar was not a constraint imposed on the project. It was the specification. That is the condition most RAAC work in the UK now shares.
The same system, from the same factory, since 1992
EXTEND SYSTEM was not developed for RAAC. It was developed in 1992 for aluminosis, and it has been extruded in Barcelona ever since — through carbonation, through corroded steel, through deteriorated timber, and now through RAAC.
That continuity is deliberate. The profiles specified today are the profiles we will still be manufacturing in ten years, and the basis of calculation behind them has been tested and refined across three decades of installed work.
When you specify EXTEND, you are not specifying a product built for a moment.
Josep Maria Vulart i RieraArchitect · CEO, SÉNETON, S.A.
How we work
We are the manufacturer. We do not carry out building surveys or condition assessments — that work belongs to your structural engineer or surveying practice.
- You send the information. Structural drawings, spans, loadings, and the findings of whoever assessed the building. Photographs help.
- We prepare a preliminary assessment. Our technicians size and calculate the beams required.
- We issue a quotation. Normally within a few working days, with the calculation basis for your engineer to review.
- We manufacture. Beams are extruded and cut to your spans in Barcelona under EN 1090-1 Factory Production Control.
- Your contractor installs. With our training and assembly certification. Two or three fitters, no welding, no hot works.
Common questions
Do you survey buildings to identify RAAC?
No. We are the manufacturer, not a surveying practice. Identification and condition assessment sit with your structural engineer. Send us their findings and we will calculate and quote the beams required.
Do occupants have to move out?
In most cases, no. The beams are light enough to carry by hand, they assemble without welding or screws, and work can be sequenced bay by bay. The Mataró school was completed within a single summer holiday.
How long does installation take?
Two or three fitters install 8 to 10 beams a day, roughly 25 to 30 m². A typical roof bay is finished within one to two weeks. Because there is no welding, work can run outside normal hours.
Is this a temporary prop?
No. EXTEND SYSTEM is a permanent, self-supporting structural system that transfers load to verified supports. It is not a temporary shoring arrangement.
Is CE marking accepted in the UK?
Yes. CE marking recognition for construction products placed on the Great Britain market was extended indefinitely in September 2024, with a minimum two-year transition period committed should that position change.
What does it cost?
Cost depends on the number of beams, the spans and site access, so we quote per project. Send us the drawings and we will come back with a firm figure, usually within a few working days.
Request a preliminary assessment
Send us the structural drawings, the spans and loadings, and your engineer’s findings. Our technical department will size the beams required and return a calculated quotation, normally within a few working days.
Or email seneton@seneton.com directly.
