When To Worry About Cracks

In honour of our 60th blog post I make no excuses about re-visiting an important theme in the world of Structural Engineers Reports – cracks. A common phenomenon in our homes, and a frequent reason for a call to our office, just how much should we worry about them?
Our Engineers say that cracks are usually ‘nothing to worry about’ but, in some cases, they can be the first sign of a structural problem, so it is always a good idea to investigate and understand why they have appeared. Cracks can occur as a new building or renovation work ‘settles’, particularly where there is new plastering. Some cracks may be caused by a change in temperature or humidity, which is quite normal and rarely of structural concern. Cracking can also indicate that there is a problem with the building’s foundations however, which of course is potentially rather more serious!
So, when should you worry about a crack?
• Measuring from 1-5mm wide, these cracks may come and go and probably only need monitoring. The solution will usually be to fill them, paint over and forget about them – still a good idea to get a professional opinion though as they might be the first sign of something more serious.
• Wider cracks between 5-15mm could be the sign of a more serious problem and should be assessed by a Structural Engineer with some urgency as more radical work might be required to correct the underlying problem.
• Any crack more than 15mm wide could indicate severe structural damage or subsidence and requires immediate intervention from a Structural Engineer as there could be a danger of collapse.
The shape of the crack is also telling. Diagonal, stepped cracks, especially around windows and doors, are likely to be due to foundation movement and should be closely monitored. Vertical cracks are more likely to be due to things like changes in temperature or shrinkage and so may be less serious.
Either way, it is always best to seek the advice of a Structural Engineer, even if only to give you reassurance that all is well.