Newman’s are currently undertaking wall tie replacement, London for one of our council clients.
We were called upon to carry out a wall tie survey to 15 properties suffering signs of wall tie failure. The classic signs of horizontal cracking within bed joints highlighted the defects and upon our visual and intrusive wall tie survey we found that the existing ties had corroded causing them to expand and lift the bricks work.
Wall Tie Replacement
Wall tie failure is a common defect among houses built in prior to the 1980’s and buildings of all types and constructions suffer from wall tie failure due to the ties being constructed from mild steel or wrought iron and moisture penetration through the pointing of a building reacts with the metal and causes it to rust and expand lifting the masonry. There are other causes of wall tie failure of which we will cover in future blogs.
With this particular project that is underway wall ties are being located using a metal detector and isolated using Twistfix’s unique Clansleeve’s that encompass the failed tie in a sleeve filled with resin that prevents any further corrosion. The sleeve slips onto the tie within the bed joint alleviating the need to remove any bricks.
Wall Tie Replacement
The replacement wall tie we are using for this wall tie replacement, London is Twistfix patented 9mm stainless steel patented CD tie which enables us to install the wall ties quickly as only a 7mm pilot hole is required to drive the tie in. Using this tie enables us to complete over an elevation per day and it also becomes load bearing as soon as it is installed removing the need to wait for any setting times for resins or fixings.
If you have signs of wall tie failure or require a wall tie replacement specialist be sure to contact Newman’s today on 0333 444 0154 or email enquiries@newmans.com
Tower block construction began in the 1950’s with the first tower block in Britain being built, The Lawn in Harlow, Essex. The need for housing influenced the decision for tower block construction and it boomed.
The Lawn, Essex
Tower blocks are constructed usually using three methods; in-situ, Steel frame with infill panel and pre-fabricated panels. In theory all three methods of construction should have provided structures free from structural defect and with stand the test of time. In reality many high rise structures are in urgent need of refurbishment to ensure they do not enter a state of disrepair with the only solution being demolition.
With all three methods of construction there are common structural defects found that are often similar across the country. Cracking is usually evident within the external and internal fabric of the structure and the defects are often linked to one or more of these causes of movement, thermal movement, lack of movement joints and failed wall ties or inadequate wall ties. Poor construction methods during the build phase. Concrete failure as well is a common structural defect found which can be caused by many factors such as oxidisation of the reinforcing steel, the reinforcing steel being too close to the surface of the concrete which again causes oxidisation freeze thaw action and chemical reaction to name but a few.
Trellick Tower, West London
Newman’s are approved designers and installers of the Twistfix and Thor Helical repair systems combined with our experience we provide our own specifications for wall tie replacement schemes as well as crack stitching and masonry beams. We are also approved installers for Fosroc and Sika concrete repair mortars and resins, mastic and coatings.
When assessing the requirements for repair to tower blocks you should only use an experienced contractor and Newman’s surveyors and engineers have extensive experience carrying out structural surveys and designing structural repair programmes to reinstate the structural integrity to tower blocks. We have worked closely with many principal contractors and façade installation specialists to provide insurance backed repair schemes prolonging the life of the tower block.
We can also provide rope access surveys and installation on schemes that it isn’t feasible to supply and erect traditional access methods such as tube and clip scaffolding or cradle access.
That phrase is commonly heard within the Newman’s office, being a common problem to Victorian and Edwardian built properties we are able to offer modern methods of structural repair to prevent and restrain outward movement.
Bowing House in Need of Restraint
Bowing walls are caused by a lack of lateral restraint, which allows the masonry panels to move independently often outwards severely weakening the structural integrity of the property.
This is often evident at the levels of the masonry where the floor joists run in accordance to the floor and ceiling joists. Tying into the floor and ceiling joists is essential in repairing and restraining the movement and traditional tie bars which are visible on many period properties are no longer required.
Lateral Restraint Ties
Newman’s utilise the Twistfix Heliforce system providing lateral restraint by inserting 1.0m, 1.5m or 2.0m ties into the floor and ceiling joists with a resin fix into the brick work providing an almost invisible repair once aesthetic brick repairs have been carried out. Incorporating lateral restraint ties with helical bar creating deep masonry beams and replacement wall ties remove the need for expensive intrusive and dangerous remove and rebuild techniques that may have been previously used.
Author: Jon Newman
Posted:
Categories: Bowing Walls
