The requirement for a survey of the cavity wall can be triggered by a variety of reasons.
A house could be old, and metal ties in older homes can be damaged and rust, so the inspection may just be an exercise to make sure that corrosion of the wall tie isn’t a problem.
Wall tie corrosion can be suspected due to cracks in the wall possibly noticed by the owner however, most often, it’s the issue is brought up by a surveyor working for a buyer of a home or mortgage lender.
There could be a bulge or another flaw that could indicate that there is a problem. In addition, the wall ties should be checked in order to illuminate to determine the reason of the motion is identified.
Whatever the motive behind conducting a wall tie inspection the process is simple and generally will take less than an hour or less.
So , what is it you do? Contact a Wall Tie Surveyor…
After arriving on the site after a brief introduction, and reassuring discussion with the owner The surveyor (with permission from the owner) will perform an appraisal outside of the home; it’s restrictions, if any and whether there is any cavity or if there is any cavities wall insulation or are there any cracks, and if yes, the size and shape of them.
After this, he’ll employ a metal detector to determine the location of the wall tie-ups. This usually takes place at the ground level, however there are times when he’ll require ladders, especially when cracks exist at a higher levels or if the building is constructed with different materials on the walls, for instance, unfinished brick at ground level , and rendered stone or brick at higher levels.
If you have found a few connections to examine, a rechargeable drill is employed to make an inspection hole close to each of them; typically around 12mm in diameter . It is then drilled within the beds-joint (between the stones or bricks when they aren’t covered by pebble-dash or render).
For examining the ties using a boroscope. It is a more robust model of an endoscope that is essentially a form of periscope that is contained in the 10mm diameter tube of steel that has a viewing window to view the ties within the cavity as well as an illumination source that illuminates the wall tie that is being targeted. In the case of a cavity that isn’t completely insulated, a remarkable image of wall tie is possible. Clients and homeowners are welcome to shadow our surveyor or even examine the wall tie itself.
The wall tie inspection was used to be a highly personal process. One surveyor’s “failing” tie being judged to be “okay” by a different surveyor. This caused disputes and confusion. Fortunately, in 1995, the Building Research Establishment (BRE) issued guidelines via BRE digest 403 “Installing Wall Ties “, that outlined how to visually assess existing wall ties’ grades and also what recommendations to make (or not) according to the state of the ties.
BRE 401 sets out nine types for wall tie corrosion beginning with the first: Brilliant and shiny but no issue, up to number 9: Very corrosion-prone and laminating requiring urgent repair is required. The initial assessment of the condition of the wall ties will be used to determine what next step (if any) is required.
But the person who is surveyed will be required to take into consideration other elements before a final decision is taken:
Are there cracks or movements that are caused by the squeak of old rusty tie?
What kind of wall ties do you have? Thin fishtail type or thick wire-type wall tie?
Did you have enough wall ties in place at the time of construction And are they in proper places?
Do you have cavities wall insulation or is it planned for installation soon?
What is the angle of the wind and the orientation of the structure?
The majority of the time, a decision is made in a matter of minutes, however our surveyor will snap photos of the wall tie through his boroscope for future inspection and also to keep a log of the results.
The procedure above is the most commonly used method but there are times when the wall ties can be difficult to discern. The wall insulation of the cavity may block the view of the boroscope and make the process of imaging and viewing difficult. The presence of other debris or a narrower cavity could also hinder an boroscope wall tie-up survey. In these instances, an additional method of invasiveness is required.
That’s how…
The wall ties were identified by the metal detector. Currently, one or two small holes is created in the bed-joint precisely in the location of the tie. The chisel can then be employed to expand the gap to ensure that the wall tie can be seen inside the bed-joint, clear of any debris, and accessible to be inspected and photographed. This process takes slightly longer than a normal borescope survey. The bed-joint that is damaged is repaired but, in the event that a wall has been rendered or pebble-dashed there will be a patch of rendered render that will not be the same as the original material.
When the work is completed, usually on the next day the surveyor writes his wall tie report.
This Wall Tie Corrosion Report contains all the information you require, such as:
The wall’s construction.
What kind of cavity wall ties are there in the first place? Are they galvanised pitch coated, or stainless steel?
Which condition are they in What condition are they in? Using BRE 401 as a guide.
A few photographs of the ties shot through the boroscope. Annotated to indicate their location, and pictures of the ties exposed at beds joints if this method was needed.
If the ties don’t need any repair work, then it . Job done.
But, if the condition of the tie does not meet the requirements that of BRE 401 or, if there are circumstances that require acceleration of the timeline for replacement of the wall tie (impending cavities in the wall, for instance) The wall tie replacement plan and a price will be provided in the wall tie report.
The information will also include the reason of the recommendations and a full description of the information required and will be included in the estimate for the replacement of the wall tie important safety information, which is legally required since the installation of the wall tie requires scaffolding and construction work. And of course the quote itself that is always a fixed-price and not an estimate.
The wall tie reports are created to conform to BRE 401 so it also contains information on the credentials of the personnel who install the new wall tie system; their experiences in testing the procedures used to test the new wall tie and the details of the guarantee for wall ties and the insurance plan in place to ensure the guarantee over its entire period.
There are some exceptions to the above because there are many different types of houses that do not fit into an’standard’ model, and the surveyor might have alter his method in order to make a sound and reliable conclusion.
After that, the surveyor will then repair the holes for inspection and sweep all dust prior to leaving the site.
