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Helix Spiro Remedial Wall Ties

Replacement Wall Tie System

TYPICAL APPLICATIONS

WALL TIE FAILURE

The Problem

The increasing incidence of wall-tie failure due to corrosion is now causing very serious concerns in many parts of the United Kingdom. The problem has arisen because the zinc coating applied to the mild steel ties used extensively to link cavity wall constructions was insufficient to prevent corrosion. Up to 1981, when the British Standard was amended to specify thicker coatings of zinc, the anticipated life of galvanised ties was only 15-20 years. It is now estimated by the year 2000, the ties used in 7 million buildings will have exceeded their minimum life expectancy.

Identification

Early identification of wall-tie failure is crucial before any serious structural damage occurs. Where conventional ties have corroded within the outer leaf of the wall . Characterstic cracking is evident as a regular pattern in the horizontal mortar joints. Carrying the ties, usually every 6th course. The position of the ties can be located by metal detector. Visual inspection by the removal of bricks or by the use of an endoscope can quickly confirm tie failure. Where corrosion has not occurred in the outer leaf, the first indication of wall-tie failure could be the collapse of all or part of the wall.

The Solution

Spiro-Remedial Ties provide an inexpensive and permanent solution to wall-tie failure. They offer the following advantages.

Specification

Spiro-Remedial Ties are manufactured from austenitic stainless steel Type 304 to BS1449. For particularly corrosive and aggressive conditions Type 316 stainless steel is available on special order.

Spiro-Remedial Ties are made from 2mm x7.5mm Spiro. The appropriate Spiro-Remedial Tie for a particular cavity width and situation should be specified. Contact us for details.

Installation

  1. Using a 10mm masonry drill bit, horizontally drill through the brickwork of the outer leaf and into the inner leaf to give a measured hole depth of 70mm. Simple markers may be attached to the drill bit to establish cavity width (which coulld vary within the same wall) and the depth of hole in the inner leaf.
  2. Remove all dust from the holes in both leaves using an air­line or extended bottle brush and water.
  3. Using an extension nozzle to reach the depth limit of the hole in the inner leaf; inject a suitable polyester or epoxy resin to fill the hole. The Ramset Chemset Injection System produced by Ramset Fasteners Ltd. is parcularly recommended for fixing Spiro-Remedial Ties.
  4. Insert the Spiro-Remedial Tie into position.
  5. Inject resin into the outer ieaf hole to bond the tie.
  6. Point and make good with colour-matched mortar.

Notes

STRUCTURAL PERFORMANCE

For details of structural performance contact us.

Helix Fixings. 102 Hillside Crescent, Cheshunt, Herts, EN8 8PJ, UK.