Cavity Wall & Tie Surveys
Alpine Property Group LtdLocal Surveyors Near You.
Cavity wall ties are used in order to tie the two wall skins together when cavity wall construction is utilised. Later properties have galvanised steel ties, however earlier properties from the early 1900's through to the mid century were not galvanised, and are therefore at increased risk of deterioration. This is increased as the structural condition deteriorates, and also when cavity fill insulation is inserted within the cavity. Both the deterioration and the insulation increase the risk of the tie becoming damp, and in turn rotten.
When a wall tie becomes rotten, it is at risk of breaking, in turn reducing the structural stability of the elevation. Our survey is undertaken by scanning the elevation for the steel ties, and thereafter drilling the outer wall skin in order to insert an endoscope camera. The cavity is surveyed for silt and debris, and also to ascertain the condition of the wall ties.
On completion a full detailed report is provided, which will include photographic evidence of the cavity and wall tie condition.
- We are totally independent of all contractors
- We have over 30+ years of surveying experience
- We have offices and Surveyors that cover Central & Southern England, Greater London & Wales
As explained under Damp Surveys, cavity walls were introduced in 1932, in an attempt to stop internal penetrating damp that had been an issue with previous solid wall constructed properties. The structure was simple, normally a 100mm external wall, a 50mm air cavity, and then a 100mm internal wall. The two walls were held together by various forms of wall ties. The cavity allowed any absorbed water to drain internally down the cavity, without it passing into the internal wall.
In the 1970’s cavity wall insulation became recognised as a natural way to increase the insulation in a cavity wall constructed property, and in the 1990’s it became compulsory under building regulations to install it.
There was a reason for an air gap, and it was a very good reason, to stop the bridging for water to pass from the external to the internal walls as previously described. In our opinion, and as witnessed by many home owners who are suffering with damp as a result of saturated insulation, filling the cavity was a costly mistake. At the time home owners were told that the insulation be it beads or similar, would not act as a bridge in the cavity as the water/moisture would drain down through it, and therefore it would not transfer water to the internal wall skin. At the same time when the external wall was in perfect condition, was non porous without deterioration, and we were not suffering with the wettest Winters in many decades, it would probably work, however this is no longer the case for many people.
We are experiencing more and more clients who have Penetrating Damp caused by saturated cavity wall insulation bridging the gap. And where the cavity insulation has slumped to the lower levels of the cavity, again it is often misdiagnosed as a DPC issue, and wrongly expensive injection DPC’s recommended, when in fact only the saturated insulation needs removing. In addition we are experiencing properties with higher level damp patching that can be caused by an external defect allowing water to penetrate the insulation, and then in that area penetrate the internal wall. This can also be misdiagnosed as deteriorated wall ties causing damp spotting.
In order to confirm the cause, and in addition to our non-intrusive methods, with authorisation to drill a small hole, we would inspect the cavity with one of our small end (8mm) cameras, and ascertain the true condition of the insulation. On the rare occasion, it may be necessary to remove a brick, to allow us to extract a sample of the insulation.
On completion a detailed report will be provided, detailing exactly what has been undertaken as part of the investigation or survey, the results, and our unbiased recommendations for the rectification of the issue.
As previously stated, cavity walls became common construction practice in 1932, and with them the cavity wall ties which were bonded between the brick work within the mortar, at regular spread intervals of 900mm horizontally, and 450mm vertically.
The ties were generally made from steel, although in earlier years other less strong materials were utilised such as slate and specially shaped bricks to tie the external and internal skins. In later years the steel ties were galvanised in an attempt to prolong their life span.
As we know, water and moisture penetrates the external skin of the wall, and in turn the moisture reacts with the steel ties causing corrosion and deterioration. This in turn causes the metal to expand, and then the joint between the brick work to crack, allowing yet more water penetration, thus increasing the deterioration of the tie, and increased potential for dampness within the property. When the moisture in the crack freezes during the colder weather, the water expands again causing the crack to open further.
The defects that become visible as a result of deteriorated wall ties are longitudinal cracks along the wall, or in much worse cases, bulging of the wall, which is normally a result of incorrectly spaced ties across the cavity, therefore not providing the bond required for the particular wall.
As there are so many issues related to wall tie deterioration, or the lack of the ties, Alpine Damp will undertake a thorough survey to establish the extent of the problem, and in order to provide recommendations for the rectification. As per the damp surveys offered, Alpine Damp have no connection to wall tie installation companies or builders, and neither do we provide the service, thus negating any financial benefit from recommending unnecessary works for the client.
We will scan the effected wall with a metal detection device, in order to locate the ties within the cavity, marking them externally with chalk. This will allow us to confirm if there is an issue with the density and spread of the ties. We will then drill a small hole through the external skin, and seal it on completion. This will allow us to insert a small ended camera, and inspect a sample of the ties, thus allowing an accurate report on their condition. On rare occasions it is necessary to remove a brick, in order to clearly see the tie, and this is normally when cavity wall insulation obstructs the visibility.
On completion a detailed report will be provided, detailing exactly what has been undertaken as part of the investigation or survey, the results, and our unbiased recommendations for the rectification of the issue.
