Survey Procedure
These to recommendations apply to properties not exceeding three stories in height.
The property may either be traditional construction using bricks, blocks or stonework to form individual leaves with a timber inner leaf. The cavities would be expected to be within the bracket 50mm. to 75mm.
The object of the survey is to identify the defects caused by wall tie failure and/or to establish a lack of walls in a property. The result of your appraisal is to recommend, in report form, remedial action if any is necessary.
Before recommending the use of remedial wall ties it must be established that the walls are otherwise sound and that the result of wall tie failure has not adversely affected the integrity of the construction.
Permission must be obtained to damage the fabric of a building and you are responsible to make any good disturbance.
When preparing a quotation from a specification and drawing it is recommended that a site visit be made to confirm the construction and cavity widths thereby confirming that the correct length and type of wall tie has been specified.
External Defects
Horizontal cracking at regular intervals. Normally every five to seven courses and frequently this will be evidenced by re-pointing in wide joints. The metal detector will confirm the presence of wall ties along these joints.
Outward bulging of brick work may indicate wall tie corrosion. The inner leaf of the wall being more firmly tied into construction is less likely to move, with the rust lamination of the wall ties, than the outer leaf. This outer leaf may lift at the horizontal cracks, and/or be forced outwards.
A pagoda roof effect may be seen at gable ends where the height expansion of a gable wall has caused the roof to lift. misalignment if slates at the roof verge is an indicator.
Lifting or sagging of lintels and cills can indicate wall tie corrosion.