The stairwells of the grand, neo-classical, eighteenth century property, had been suffering from deflection, caused in part by alterations to the support for the cantilever landings.

The repair solution was required to impart the necessary strength and be virtually invisible upon completion. Following evaluation, consulting engineers Gifford and Partners in consultation with the National trust, chose the Sika CarboDur system. Whilst the employment of CFRP systems is well-established and used widely for the upgrading of all types of structures in the Civils market, domestic and residential installations are much rarer. Nevertheless, the system proved ultimately ideal for the task in hand.

Carbon fibre reinforcing polymer (CFRP) systems comprise pultruded carbon fibre plates of various widths, thicknesses and strengths, bonded into place with a specially formulated two-component, cold-cure, epoxy based structural adhesive. The adhesive can be employed on both damp and dry substrates.

CRL’s first task was to channel out the undersides of the landings to a depth able to accept the 50mm wide CFRP plates, which were bonded into place with no additional support. Once cured, the plates were coated and sand filled to form a bonding bridge for a levelling mortar, which was applied to return the repaired area back to the level of the surrounding substrate. After final painting, the strengthening works blended perfectly into the stairwell structure.

The project provided a perfect example of how correctly installed modern materials and techniques can be utilised to maintain old and listed buildings with minimal adverse visual impact.