CFRP Strengthening for RAAC

Carbon fibre reinforced polymer (CFRP) strengthening restores the capacity of RAAC in place, without the cost, programme or disruption of replacement. Structured Carbon designs and manufactures its CFRP in the UK for each building, tuned to the exact strength the structural calculations require.

What CFRP strengthening is

CFRP bonds high-strength carbon fibre to the surface of a structural element to add the tensile and shear capacity it needs. The carbon fibre is thin, light and exceptionally strong for its weight, and once bonded it becomes a permanent part of the structure. Unlike steel, it does not rust or corrode, and unlike the RAAC it strengthens, it is immune to moisture, the very thing that causes RAAC to deteriorate.

Why CFRP suits RAAC

RAAC is lightweight and low in strength, with limited reinforcement, so the right remediation has to add capacity without adding load or stripping out the roof. CFRP does exactly that:

• Lightweight. It adds strength without adding meaningful dead load, unlike heavy secondary steel or timber propping.
• No loss of head height. Bonded to the surface and only millimetres thick, it leaves the space below intact.
• Moisture-immune. It does not rot, rust or degrade, so it solves the problem without re-introducing it.
• In place. It is applied without removing the structure, so the building can usually stay in use.

Engineered for your building, not off the shelf

This is the difference that matters. Because RAAC is a low-strength material, the strengthening has to be matched to it and to the loads of each specific structure. Our CFRP is not a single fixed product. It is built from a range of elements that are tuned to deliver the exact strength the calculations require, no more and no less than the structure needs, every time. We design and manufacture it in our own UK facility, including small bespoke batches of as little as ten or a hundred linear metres, so each scheme is matched precisely to its design rather than forced to fit one product. The system is in production now, so we can mobilise quickly.

CFRP strengthening compared with the alternatives

• Versus full replacement. No demolition, far lower cost and a fraction of the programme, with the building kept in use.
• Versus steel or timber propping. No added dead load, no loss of head height, and a permanent solution rather than a temporary measure.
• Versus doing nothing. A monitored, engineered solution that restores capacity and extends safe service life by decades.

Read more about the wider approach on our RAAC remediation page.

Frequently asked questions

Is carbon fibre strong enough to strengthen RAAC?

Yes. Carbon fibre laminate has very high tensile strength for its weight, far higher than steel pound for pound, so a thin externally bonded layer can restore the capacity a RAAC panel has lost. Because RAAC is a low-strength material, the strengthening is engineered to match it precisely rather than overwhelm it.

Does CFRP strengthening add weight to a RAAC roof?

Very little. CFRP is extremely light and only millimetres thick, so it adds capacity without adding meaningful dead load, unlike heavy secondary steel or timber propping which loads the structure further and reduces head height.

Will CFRP strengthening reduce head height?

No. Because the carbon fibre is bonded directly to the surface and is only millimetres thick, it restores strength with effectively no loss of head height, in contrast to steel or timber propping which intrudes into the space below.

How long does CFRP-strengthened RAAC last?

CFRP does not rust, rot or corrode and is immune to the moisture that degrades RAAC, so once bonded it becomes a durable part of the structure. Properly designed and applied, it can extend the safe service life of RAAC by decades.

Is your CFRP an off-the-shelf product?

No. Our CFRP is designed and manufactured in the UK for each application, tuned to deliver the exact strength the calculations require for that structure. We produce it in our own facility, including small bespoke batches, so the strengthening is matched to the building rather than forced to fit a single fixed product.