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Wall Tie Replacement
Wall ties are used to join the internal and external walls (or leafs) of a cavity wall that is installed during construction. Wall ties corrode over time and this expansion causes the mortar joints to force apart, causing damage to the masonry. It is necessary to replace your wall ties when the original wall ties have corroded or if they were installed incorrectly.
Why Do Cavity Wall Ties Fail?
Cavity wall tie failure can be a consequence of a construction defect; for example where the original 'built-in' cavity wall ties have been omitted, incorrectly fixed or fitted with masonry ties that are too short.
Alternatively, failure may be a result of a buildings’ aging process, whereby wall tie corrosion may have compromised the load-sharing capacity of the wall structure. Whatever the cause, the most effective way of solving the problem is replacing the cavity wall ties.
The corrosion of the steel wall ties causes the wall ties to expand because the metallic oxide occupies a greater volume than the pure metal. This force separates the bricks above and below the bed joints in which the wall ties are laid.
The corrosion of the cavity wall ties or the lack of sufficient cavity wall ties used in the original construction means that many properties require either further remedial wall ties to be inserted or the original cavity wall ties need to be replaced.
Here at Permagard, we stock an extensive range of replacement wall ties.
Types of Replacement Wall Ties
Different wall ties serve different purposes. For example, wall ties intended for use when constructing new walls should not be used for wall tie replacement. The typical types of wall ties are below:
Mechanical wall ties
Mechanical remedial wall ties use a 304 grade stainless steel rod which is threaded and has special expanders on each end, installed simply by drilling 10mm holes at the specified intervals, insert the remedial wall tie. Fixing the wall tie simply requires the use of a cordless drill to spin the nut on the end as this tightens it allows the bar to rotate and the inner expander to engage with and tighten onto the inner wall leaf.
Resin-Resin wall ties
Threaded Bar Resin Wall Ties can be used in almost all building materials i.e. brick, lightweight block, timber frames and even mortar but are particularly used where the quality of the inner and outer leaf substrates are in doubt.
Helical Drive ties
Helical drive ties are used in many different types of building materials to tie wall leafs together. They are installed by drilling a pilot hole into the substrates. Then using a special adaptor on a drill, the helical drive tie is driven into the substrates tying them together.
Wall Tie Replacement Procedure
Replacing wall ties is relatively easy, providing you have the correct knowledge and equipment. First you need to identify the positions of the existing cavity wall ties
Install remedial wall ties in positions staggered from the original cavity wall ties.
Ensure that you carry out the replacement in a uniform spacing pattern: a diamond formation with remedial wall ties at 900mm centres in courses set 450mm apart. At door and window openings the spacing is reduced to 300mm vertically.
Make sure that the original cavity wall ties are isolated to prevent further damage to the cavity wall.
Fitting Clan Sleeves around the external end of the cavity wall tie will isolate the cavity wall ties.