Cavity Wall ties
Wall ties are used in cavity walls to hold the two walls together, without wall ties the two walls can bulge or bow. In older properties steel wall ties were used which rusted and corroded away due to the moisture and condensation in the cavity. Stainless steel wall ties or sometimes galvanised steel wall ties are used, which are far better as they do not rust. Often in older properties the wall ties will need replacing as the old ones have rusted away, there are companies which specialise in this and should give a ten year guarantee or perhaps longer. Full structural surveys often pick up corroded wall ties, normally a hole is drilled into the cavity and a camera is used to survey the cavity. Work like this needs doing or it can effect your mortgage decision. Sometimes pieces of slate were used to tie the two structures together but new building regulations have deemed this unsuitable.
In new work installing wall ties is simply a matter of bedding them in the mortar at the specified intervals.
 |
These wall ties are simply bedded into the mortar whilst laying the bricks! |
In older renovation work installing them is a little more tricky and involves drilling holes at specified intervals (normally every metre), either from the inside or the outside of the property. In my opinion it is better to drill from the inside as patching up the plaster is far easier than trying to hide the holes on the outside of the house. There are two ways of attaching replacement wall ties, one involves drilling the hole straight through the inner brick and into the second brick then injecting resin, inserting a stainless steel wall tie and then injecting resin again. The resin bonds the wall tie to the outer and inner wall. The other method uses a stainless steel rod which is threaded and has special rubber grippers on each end, this is drilled as the resin type wall tie but this type of wall tie simply requires the use of a cordless drill to spin the nut on the end as this tightens both ends simultaneously and grips both the outer and inner wall.
Here you can see that to fit replacement wall ties the first wall needs drilling straight through and the second one needs drilling to the correct depth for the wall ties being used
 |
This is the newer type of wall tie which is stainless steel with neoprene at each end, these are very fast to install. |
 |
This is a diagram of a wall tie in use, you can see that it holds the inner and outer wall together. |
 |
Here is evidence that the wall ties have been replaced, small circular holes that have been filled in this case with red mastic. |
