CASE STUDY

Wall Tie Replacements and Masonry Repairs
St Marys House, Eastbourne

St Marys House is a large 7 storey commercial building based in Eastbourne, East Sussex, housing multiple businesses and serving local authority needs.  The building was built around 1960’s and constructed using concrete internal frame walls with cavity construction masonry outer walls.

The problem

The perimeter masonry walls were being affecting by significant visual horizontal and vertical cracking throughout the majority of the elevations, but mainly affecting the smaller panels between window openings.

The cause of the movement was investigated and diagnosed primarily as corrosion and delamination of the original galvanised fishtail type ties (mild-steel). Although in many cases the corrosion affecting the ties could be visually seen where masonry had been lifted and pointing de-bonded. However our inspection was further aided by the use of an image Boroscope to verify our findings and provide photo evidence to the client within a full written report.

Additional vertical and step cracking was also found to be affecting various panels due to the severity of the corrosion. This caused some weakening and de-bonding of the affected masonry panels meaning additional remedial repair solutions were required.

The solution

From our inspection, we were able to provide the client with a full written report and diagnoses of issues found. Our report included photographic evidence, including Boroscope images, and a full remedial repair solution and specification covered by a long term guarantee.

Our specification allowed for the installation of replacement remedial wall ties (Helifix Resitie) installed to recreate the lateral bond to inner and outer leafs of masonry. This type of tie is resin bonded to both inner and outer leafs and was selected, for this particular construction type, due to different internal leaf construction of either masonry blockwork or concrete frame. The installation of the new replacement ties was carried out in accordance with manufacturers guidelines and recommendations and installed in a pattern that complies with modern building regulations Rule 13 with additional ties at jambs and reveals.

To prevent further corrosion and expansion of the original wall ties, our specification included for the full isolation of the ties within the outer leaf masonry.

To provide additional reinforcement and re-connection across the most affected external masonry panels, we also carried out the installation of Helibars at regular intervals in accordance with manufacturers guidelines and recommendations.

Both the wall tie and Helibar installations were carried out with minimal noise and disruption to the users of the building. Once drill holes, isolation slots and mortar line chases were made good, this left minimal visual evidence of the repairs.

Expert opinion

“We have been approved installers for using Helifix products for many years and find them to have a complete range of ties and repair solutions, along with excellent data sheets and technical backup.  We were therefore able to offer the Client a complete solution for external masonry repairs with a competitive cost.”

Graham Deacon of CavityTech Systems Ltd

Further information about Helifix products can be found at https://www.helifix.co.uk/