Thor Helical Standard Details TRWT-01 to 13Retro fitted cavity wall ties can be specified where a wall has been weakened as a result of environmental corrosion effects or poor building practices. Thor Helical Remedial produce a wide range of cavity wall ties that can be fitted retrospectively to a variety of existing construction types and cavity widths. Wall Ties can be used in isolation or accompanied by a range of Thor Helical methodologies to restore structural stability to a wall. If required, we can carry out non-destructive wall tie surveys to ascertain condition, and carry out load tests on new ties at specified intervals if required.
Brick and associated 'fishtail' tie removed from a cavity wall. Note the near pristene 'fishtail' section of the tie removed from the internal skin of the wall
Note the relative thickness of the corroded end of the tie compared with the uncorroded end
Close up photograph of the same tieThe series of photographs above provide a good example of how much corroded steel wall ties can expand; and this can in some instances be up to twelve times the original thickness of material used. Note that only the section of tie inserted in the external face of this wall has corroded having been exposed to the severest weathering; but this is not always the case as wall location / orientation and, or quality of original wall tie material may dictate extent of corrosion.
The following series of photographs illustrate the typical damage pattern that corroded wall ties can create in a cavity wall, reducing its structural stability and in particular the ability to withstand horizontal wind loading. Cavity walls suffering from corroded ties generally exhibit horizontal bed joint cracking and occasionally diagonal cracks through perp joints radiating from corroded tie locations.
Typical damage created by corroding wall tie expanding and splitting bedjoint
Horizontal bed joint cracking created as symptom of several wall ties corroding in the same bedding plane
Alternative diagonal pattern of masonry cracking that can also be a symptom of wall tie corrosionThor Helical Remedial produce a wide range of wall ties to suit masonry of all types and strengths and locations. We can survey and specify a wall tie to accomodate any masonry composition and location. Most commonly used ties will be of the helical 'Drive Tie' type made of 304 grade stainless steel, or 316 grade for use in marine coastal environments.
The following series of photographs illustrate 'Drive Ties' being installed in combination with a number of 'Crack Stitch' bars to restore structural integrity to a wall. All existing wall ties will have been located and removed following installation of the remedial ties.
Corroded wall tie prior to removal from the internal bedjoint of a cavity wall
Crack Stitch installed and Drive ties in position ready for installation
Drive Tie being driven home using specialists driving toolAs an approved specifier and installer of the Thor Helical products we can offer an insurance backed 10 year warranty on Masonry Beam works for a small additional fee through Construction Guarantee Services Limited.
