Wall Tie History and Background

Cavity walls incorporating metal wall ties have been used since the beginning of the nineteenth century but it was in the 1930’s building boom that produced large numbers of cavity construction dwellings. From 1945 cavity wall construction became the normal for houses and many other buildings.

The early metal wall ties produced mainly from wrought iron or cast iron performed satisfactorily but in more recent years mild steel wall ties have been used and despite galvanising or bitumastic treatments have been found to suffer from wall tie corrosion. A British standard was produced in 1945.

The estimated life of these mild steel wall ties is appreciably less than the sixty year life expected. The 1945 standard was relaxed in 1964 and 1978. And in 1981, when the extent of the problem was registered the British standard was amended to triple the zinc coating thickness on a wire tie.

A number of cases of distress of cavity wall attributable to wall tie failure have occurred in the United Kingdom and it is now clear that the problem could eventually affect all the cavity wall structures built before 1981, some 10 million dwellings and will not in future be confined only to cases of poorly made ties.

Wall tie failures reported to the Building Research Establishment include inferior coatings of bitumen, insufficient zinc galvanising on mild steel, aggressive mortars (particularly black ash), exposure to marine climates and permeable mortars such as lime that permits rapid carbonation.

It is estimated that over 3 million houses of cavity wall construction were built before the introduction of the 1945 standard. Between 1945 and 1964 an additional 3 million houses were built to the British standard BS 1243 – 1945 with wire tie life expectancy of 15 to 31 years and a stripe tie life expectancy 31 to 61 years. From 1964 to 1986 over 4 million houses were built to the lower British standard with a wall tie life expectancy of 23 to 46 years.

It was estimated in the 1986 survey of English houses that around 12 million properties exist with cavity walls of which the number requiring some repairs to wall structures is approaching one million.

Why are wall ties Important

Wall ties are a very important part of your structure. They allow your property to:-

1. Have a cavity which stops damp transferring through to the inside.
2. Allow point load of pressure to be transferred over a larger surface area, internal and external brickwork.
3. Reduce wind suction in gale conditions.
4. Stops the two walls pushing apart and causing structural damage.

Wall Tie Corrosion, indications and reasons for wall tie failure

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Areas covered Dorset – Bournemouth – Poole – Weymouth - Christchurch – Ringwood – Wimborne – Ferndown – Corfe Mullen – Parkstone – Dorchester – Shaftesbury – Blandford - Westbourne – Wareham – Oakdale – Maiden Newton – Bridport – Yeovil – Warminster – Gillingham – Mere – Sturminster Newton – Salisbury – Southampton – New Forest – Fordingbridge – Wiltshire - Hampshire