RAAC Strengthening vs Replacement: What Our Tenders Show

This is not the story of a single project. It is what we see again and again across the RAAC tenders we cost. When we price a bespoke CFRP strengthening scheme, engineered for that exact roof, against the cost of stripping it out and replacing it, strengthening frequently comes in at well below 15 per cent of the replacement cost.

Under 15%What strengthening typically costs against full replacement

£40m to < £4mOne tender we costed: a roof priced to strengthen, not replace

Tailored per roofEvery scheme designed to that exact structure, no decant

Schedule an Inspection

How we cost a RAAC scheme

When an owner faces a RAAC replacement, we cost the alternative. Neil Smuts surveys, scans and assesses the RAAC to establish its true condition and the loads it carries. John Staves (CEng FIStructE) then designs a bespoke CFRP strengthening scheme, tuned to the exact capacity that roof needs, and we price the manufacture, installation and monitoring against that design. The result is a like-for-like comparison: keep and strengthen the roof, or strip it out and rebuild it.

Why strengthening comes in so far below replacement

Replacement carries the full cost of stripping out, temporary support, weatherproofing, rebuilding and the disruption of closing or decanting the building. In-place strengthening avoids almost all of that. Because the CFRP scheme is tailored to the exact roof rather than over-specified, it restores precisely the capacity required and no more. Across the tenders we cost, that is why the strengthening price so often lands at well below 15 per cent of the replacement figure.

An example tender

On one tender we costed, a roof costed at around £40 million to replace, over a programme of roughly three years and requiring the occupants to be moved out, was priced for in-place strengthening at under £4 million, with the work measured in months rather than years and no decant. That is around a tenth of the replacement cost, well inside the pattern we see across our tenders.

What strengthening delivers

Well below 15 per cent of the cost of replacement, on the tenders we cost.
Months, not years, because nothing is stripped out and rebuilt.
No decant. The building can stay in use, avoiding the cost and upheaval of relocating occupants.
Tailored to the exact roof and designed to the precise capacity required, signed off by a chartered structural engineer.
Decades of added life from a permanent, moisture-immune CFRP solution, rather than a temporary prop.

When replacement is still the right answer

Strengthening is not always possible. Where panels are too far gone, where bearings cannot be made adequate, or where a structural assessment concludes the roof cannot be saved, replacement is the right call. We say so when we cost it. The point of pricing both is to let the engineering, not the default, decide.

What this means for your building

The same approach applies across the building types where RAAC is most common, including schools, universities, NHS and private hospitals, and other public and commercial buildings. Where a structural assessment confirms it is suitable, strengthening is almost always on the table, tailored to that exact roof, at a fraction of the cost and disruption of replacement. Prop to make it safe, then cost strengthening before you commit to replacement.