Cracking in a Building – Some things to consider

Cracking in buildings can affect any building and often is simply due to normal movement, whether that be thermal related, differential, age of the materials, alterations, etc…  However as a property owner or purchaser, when you come across a crack you are likely to be a little concerned and that is not surprising.

This short article will try to help you by providing some simple guidance as to the cause of cracks and provide some tools to help you assess the problem.

Firstly, it’s important to consider the actual situation such as how serious is the crack considered at this point in time?  When did it start?  What’s the likely cause? Is there a solution and what’s the cost?  Etc…

Cracks in buildings can be categorised using a very simple system, as outlined below:

Category of damageDegree of damageDescription of typical damageApproximate width
0NegligibleThese are usually hairline type cracking of less than say 0.1mm.  No immediate action requiredNot more than 0.1mm
1Very slightFine cracking usually easily treatable during the normal course of decoration.  Such damage generally restricted to internal walls and finishes, more rarely visible in external brickwork as well.Up to 1mm
2SlightSuch cracking can be easily filled and recurrent cracking can be covered by suitable linings.  Cracking not necessarily visible externally but some external repointing may be required and possibly doors/windows may stick and require adjustment and also weather tightness affected.Up to 5mm
3ModerateSuch cracking may require some opening up works by a mason and repointing of external masonry, along with potentially replacement of some sections.  Service pipes may be affected and also weather tightness affected.5-15mm or several say 3mm
4SevereExtensive damage which requires rebuilding works to masonry, including over doors/windows which may also be distorted.  Floors may slope noticeably, walls may be leaning and/or bulging noticeably some loss of the bearing in beams may occur.  Service pipes can be disrupted15-25mm but depends on the number and frequency of cracks
5Very SevereStructural damage which requires a major repair job to be undertaken, likely involving partial or complete rebuilding.  Danger of instability.Usually greater than 25mm, but again depends on the number and frequency of cracks.

Cracking, as outlined above, can occur for a variety of reasons and often over a long period of time.  You should always be concerned about cracking that occurs quickly and in particular if that is anything other than very slight and/or is close to elements that might be damaged as a result, for instance pipework.

If cracking occurs quickly then you may find that the cause is simple, for instance have recent alteration works been carried out?  Such works may be in the building itself or nearby, including changes to the land nearby for instance a tree removed, trench dug or a neighbour having completed works.  If you notice such cracking, then you should quickly consider the next steps and ensure that your insurers are made aware as you may wish, even if not at that point but possibly further down the line if the cracks worsen, want to make an insurance claim.

Furthermore, if the cracking is caused by works your neighbour or someone else has recently undertaken then delay may make proving the damage more difficult.

Whatever the cause, you need to identify that and assess whether it’s ongoing or not.  This is not always easy, in particular if repairs have been carried out recently or attempts made to cover the damage.

Is the cause related to ground movement, such as damaged drains for instance?  If so are there trees or other plants in proximity that may have or could exacerbate the situation?  A CCTV scan of nearby drains can quickly and relatively cheaply help you discount or confirm defective drains as a potential cause.

It’s worth noting that not all cracks in buildings are serious, which is why it is so important to diagnose the cause correctly.   There’s may situations where remedial works may be as simple as raking out and replacing mortar joints, albeit a technique called ‘stitch repairing’, which is effectively raking out the horizontal mortar bed joints at regular intervals either side of the crack and then installing steel bars which are set in an epoxy resin (see video below).

After the resin has cured the bed joints are simply re-pointed.

Whereas more serious cracking, however may require potentially disruptive and/or expensive remedial measures and could include underpinning or possibly even partial or full demolition of sections of masonry, rebuilding thereafter.

It is therefore important that cracking in a building is quickly inspected by a suitably qualified Chartered Building Surveyor who can assess the cause, suggest and potentially specify some remedial works, along with potentially working with you to manage the defect to reduce the impact upon you and the building generally.

When the cracking occurred, as outlined above, is an important factor as that can help determine whether it is ongoing or not.  The majority of cracking I notice is non-progressive, which effectively means it’s simply the normal movement of the building and is unlikely to cause serious damage, however on the relatively rare occasion that more serious ‘ongoing’ cracking is found, it’s important that this is considered properly and a period of monitoring (perhaps as long as 12 months) may well be required to do so and form an accurate opinion.

Castle Surveyors Limited are happy to discuss such problems with you, whether before the property is purchased (cracking should always be considered prior to purchase as following completion it is likely you as the new owner who has to bear the cost and inconvenience) or if such cracking appears whilst you’re in occupation.  You should always obtain the advice of a Professional Chartered Building Surveyor to consider such matters and failure to do so could result in your having to finance expensive works of repair, along with potentially severe disruption.