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Integrity restored to historic listed tower

Client: Private owner (The Naze Tower)
Location: Walton-on-the-Naze, Essex
Approved Installer: Charterbuild
Reference No: CS152

The Grade II* listed Naze Tower is an historic landmark and the only building of its type and period in the country. The 86ft tall octagonal brick tower, with 400m thick walls, was built by Trinity House in 1720, with a beacon on its roof to serve as an early form of lighthouse. It has undergone several changes of use over the years and is currently an art gallery and museum with a roof viewing platform.

Due to age, weathering and the corrosion of embedded steelwork used during various structural alterations, the Tower was suffering from multiple masonry cracking, possibly made worse by the weight of a large radar installed on the roof during World War 2.

Two major fractures ran virtually the full height of the tower, either side of the east pier, widening to 20mm at the top. Cracking to the south facing pier at 5th and 6th floor level had been addressed by installing ties and plates.

There was additional vertical cracking at many locations around the eight storey tower, which needed sympathetically repairing to restore structural integrity to this historic listed tower.

The Helifix solution

The Helibeam System was specified as it is a proven method of creating reliable concealed repairs and has a successful record of being used on listed buildings.

  • Pairs of stainless steel HeliBars were bonded, with HeliBond cementitious grout, into channelled-out mortar beds at 18 levels around the east side for the tower from the north to the south pier. They were inserted through holes drilled in the piers and dummy piers, with the ends returned at 90° into the north and south piers. The HeliBars provided lateral restraint, reinforced the masonry, distributed the structural loads and stitched cracks.

  • Individual 1m long HeliBars were bonded across cracks in the areas between the double bars, to stitch and secure the masonry, with grouted CemTies used to pin the outer brickwork back to the 1m thick south pier.

  • All embedded steelwork was removed and replaced with galvanised sections, to prevent further expansion and masonry damage, and a tension tying system was proposed to tie four sides of the tower together at the 2nd, 4th and 6th floors.

All repair work was fully concealed and, after repointing, the historic Naze Tower was restored to full structural integrity with its appearance unaltered. The engineer for the project was Phil Chatfield.