The requirement for a survey of the cavity wall can be due to a variety of reasons:
A house could be old, and metal ties in older homes may be damaged and rust, so the inspection may just be an exercise to make sure that corrosion of the wall tie isn’t a concern.
Wall tie corrosion could be a cause for concern, due to cracks in the wall possibly noticed by the owner however, the majority of times, 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 some other issue that suggests an issue. The wall ties must be examined for illumination to determine the reason of the motion is identified.
Whatever the reason behind your wall tie’s survey the procedure is easy and generally will take less than an hour or less.
What does a Wall Tie Surveyor Do?
Following arrival after a brief introduction, and reassuring discussion with the owner The surveyor (with permission from the owner) will perform an appraisal outside of the property; its restriction details as well as whether there’s any cavity or if there is any cavity wall insulation in place or are there any cracks, and if so, the size and shape of them.
Once he’s done that, he’ll utilize a metal detector in order to find the position of the wall tie-ups. The process is typically done at the ground level, however occasionally, he might require ladders, especially if cracks exist at a higher levels or if the building is constructed with different materials on the walls, like unfinished brick on the ground and rendered stone or brick at a higher level.
After locating connections to examine, a rechargeable drill is utilized to create an inspection hole in the vicinity of each one. Typically, they are about 12mm wide and positioned within the joint of bed (between the stones or bricks in the event that they aren’t covered by pebble-dash or render).
To examine the ties, the boroscope is employed. It is a more robust model of an endoscope that is essentially a form of periscope inside 10mm diameter steel tubes and has a view window to view the ties inside the cavity, and an illumination source that illuminates the wall tie that is being targeted. If the cavity isn’t completely insulated, a remarkable image of wall tie is possible. Clients and homeowners are welcome to shadow our surveyor, and even inspect the wall tie itself.
The wall tie inspection was used to be a very personal process. One surveyor’s “failing” tie, deemed 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 categories that describe wall tie corrosion starting with number 1. Shiny and bright but no issue, to the 9th one: extremely damaged and rusty – urgent repair is required. The initial assessment of the condition of the wall tie is used to determine what actions (if any) is required.
But the person conducting the survey will have to think about other elements before a final choice is made.
Are there cracks or movements that are caused by the squeak of old rusty tie?
What kind of wall ties are there? Thin fishtail type or thick wire wall tie?
Did you have enough wall tie-ups in place at the time of construction And are they in proper places?
Are there any an insulation in the cavity wall 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 the surveyor will also snap photos of the wall tie through his boroscope, to allow for future inspection and to record a note of the results.
The procedure above is the most common 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, rendering it difficult to see and imaging. The presence of other debris or a cavity that is narrow could also hinder an boroscope wall tie-up survey. In these instances, an additional method of invasiveness is required.
The wall ties were identified by the metal detector. Currently, there is a tiny hole or two are created in the bed joint precisely where the tie is. A chisel is employed to expand the gap to ensure that the wall tie appears inside the bed-joint, clear of all debris and ready to be inspected and photographed. It takes a bit longer than a typical Boroscope survey. The bed-joint that is damaged is repaired however, in instances when a wall is rendered or pebble-dashed there will be an inevitable patch of rendered render that will not match the original materials.
When the work is completed, usually on the next day the surveyor will then write his report on the wall tie.
This Wall Tie Corrosion Report contains all the vital details you require, including:
The wall’s construction.
What kind of cavity wall ties are there as well as whether or not they’re galvanised pitch coated, or stainless steel?
Which condition are they in In what condition? BRE 401 as a guide.
A few pictures of the ties captured by boroscope, annotated for their location and photos of the ties that were exposed in joint joints in the beds, if this method was needed.
In the event that the ties don’t require any work to repair them, that’s it . Job done.
But, if the state of the ties does not meet the requirements that of BRE 401 or, if there are reasons that warrant acceleration of the timeline for replacement of the wall tie (impending cavities in the wall, for instance) A wall tie replacement specifications and a quote will be provided in the wall tie report.
The information will also include the reason of the recommendations and a full description of what’s required, and is 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 actual quotation and is always a fixed cost and not an estimate.
The wall tie reports are made to be in line with BRE 401 so it also contains information on the credentials of the personnel who install the new wall tie system; their experiences and the test procedures for the new wall tie and the details of the guarantee for wall ties and the insurance plan in place to ensure the guarantee throughout its period.
There are some exceptions to the above because some houses do not conform to an’standard’ model, and the appraiser may have adapt his methods in order to make a sound and reliable conclusion.
After that, the surveyor will then repair the holes for inspection and sweep off any dust prior to leaving the the site.
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