15 Nov When Might Structural Repairs Be Needed?
Cracks in buildings are most often the result of movement, whether that’s caused by subsidence, failed materials or disturbance, and failure to deal with the problem may lead to the building’s collapse. Fortunately, though, building maintenance helps to know how to repair the damage. There are many repair techniques available — and they tend to be a lot easier and cheaper than they used to be.
What Makes Buildings Move?
The main reasons for movement include:
- Poorly restrained walls.
- Timber decay caused by water leaking inside.
- Failure of materials, especially lintels.
- Movement fatigue.
- Disturbance or impact.
Movement can also be caused by extremes of weather. An extended dry spell, for instance, can cause the soil to shrink, reducing its support for the building, while heavy rain can get in through poorly maintained roof tiles or flashing on chimneys, decaying the timbers.
What Should You Do If You Find Cracks?
Not all cracks require action, but it’s important to get them checked, either by a structural engineer or by a contractor specialising in structural repairs. In any case, if you’re claiming the repairs on your building insurance, the insurer will want a structural engineer’s report.
It may turn out that rectifying something in the environment will correct the problem — for instance, removing trees that have drained water from the soil, or whose roots have caused heave. In many cases, though, the building will need urgent structural repairs.
What Can Be Done?
The best technique to use depends on the nature of the damage, but the most common approach is to strengthen and stabilise the foundations, generally known as underpinning.
The traditional way of doing this, by excavating below the building in sections and pouring in concrete, is still appropriate in certain cases, but generally piling is the technique of choice. This involves driving or drilling lightweight metal piles below the foundations down to a more secure level and filling them with concrete or grout. It’s quicker, less disruptive and allows foundations to be stabilised even on poor-quality ground.
Other techniques that might be appropriate include:
- If cavity wall ties are corroded, new ties can be installed, sometimes without even having to remove the old ones.
- If the problem is failure of building materials, crack stitching may be appropriate, using stainless steel or resin grout for the stitching.
- Lintels can be replaced in situ if necessary, without the need for demolition.
- Resin repair and replacement techniques can be used to strengthen failing structural timbers.