A Guide to Structural Repair and Maintenance
Unwanted movement in buildings can cause a good deal of distress and worry for homeowners. Subsidence, physical disturbance and a failure of building materials are just some of the factors that can impact on the structural integrity of a property. Fortunately, while there are many reasons why a building can move, modern repair technology and advances in application techniques mean that effective solutions are on hand to tackle the problem.
There are a number of methods available to deal with the various types of structural repair. For example, cavity wall tie corrosion, a common problem in cavity walled properties, has reasonably simple and well-established remediation strategies. New stainless steel ties can be installed, either fixed into the walls using resins or mechanically. The defective or corroded ties can be isolated or removed when necessary but, in some specific situations, can even be left in-situ.
One problem we can come across is cracking as a result of movement in the ground supporting the walls and floors. This movement in a building’s structure is commonly referred to as subsidence, and again there are a number of ways that the cracks and bulges occurring in the wall as a result of ground movement can be repaired.
Subsidence can be caused by trees removing water from the soil or heave or up-lift, caused by root growth, shifting water tables, drought, corrosion, decay, poor workmanship or lack of maintenance, erosion, vibration and even salt attack.
Foundation problems and the movement of walls are all commonplace where ground subsidence occurs. Before dealing with the cracks and bulges caused by ground movement it is important to fully understand, and in most cases halt the movement, and stabilize the foundations. Traditionally this was done through underpinning – a long and costly process that often required large scale excavations to introduce large volumes of new concrete below the existing foundations.
In recent years ground stabilization using materials injected into the ground and remedial ground piles have offered a “lower impact” solution. It is important however to ensure that whatever technique is adopted that this is conducted by trained and competent ground workers – preferably members of ASUC plus. Once the foundations are stabilized it may be necessary to restore the structural and mechanical bonds that were broken when the cracks formed. This is also the case where buildings have cracked or become unstable as result of impact damage, lateral movement, water ingress, poor building practice, thermal expansion and wind loading. Methods used to resolve such problems include pinning, strapping, piling, lateral restraint systems and steel reinforced cementations anchors.
Crack stitching using profiled stainless steel bars, resin grout and other innovative products and materials, is now widely accepted as an effective method of repair. These systems are highly effective in dealing with a huge range of situations where repair, reinforcement, stabilization or when improvements are needed to the structural strength of stone, concrete and brick structures. Lintel replacement and panel strengthening can also be undertaken, often saving huge sums that would otherwise have been spent on demolition and rebuilding. In many situations invasive rebuilding and the disturbance of historic structures can be minimized with the repaired building often showing little evidence of any intervention to correct structural problems.
It is also possible to repair, strengthen and improve structural timbers using resin repair and reinforcement techniques, which have been developed and mastered by PCA members. The structural repair of important and often irreplaceable wooden structures offers an effective and highly reliable means of repairing and retaining beams, joists, lintels and other timber elements. Advanced technology, techniques and expertise were once the preserve of historical buildings, but now these methods are finding a place in the restoration and preservation of more modern domestic properties. With the knowledge and skills available in this field, it now makes sense to repair rather than replace in many situations.