and Other Helix Fixings Products
• Replacement of corroded or inadequate cavity wall ties in existing buildings.
• Cavity ties for brick or block over cladding of existing buildings
The increasing incidence of wall-tie failures due to corrosion is now causing very serious concern 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 insuffient 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.
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, characteristic 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 a 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.
Spiro-Remedial Ties provide an inexpensive and permanent solution to wall-tie failure. They offer the following advantages.
• Austenitic stainless steel – as recommended by BRE Digest No. 329
• Unobtrusive – only requires a 10mm diameter drilled hole
• Can be fixed through either masonry units or mortar joints
• Installation using polyester or epoxy resin enables Spiro-Remedial Ties to be fixed into a wide range of masonry and concrete materials
• Continuous drip allows ties to be fixed horizontally- simplifies installation
Spiro-Remedial ties are manufactured from austenitic stainless steel Type 304 to BS1449. For particular corrosive and aggressive conditions Type 316 stainless steel is available on special order.
Available in 6mm widths and 8mm widths.
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 to 70mm. Simple markers may be attached to the drill bit to establish cavity width (which could vary within the same wall) and the depth of the 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.
4. Insert the Spiro-Remedial tie into position
5. Inject resin into the outer leaf hole to bond the tie
6. Point and make good with colour-matched mortar.