Cracks and subsidence

The perception of buildings and built structures is one of rigidity and inflexibility, however the reality is that buildings move all the time. While these movements are usually too small to notice, they can result in cracks and structural damage. These cracks may indicate that there are greater underlying flaws within the property.

Movement can be caused by a range of factors, such as: ground movement, defects, insufficient foundations, or decay and deterioration. Most buildings are constructed to endure a certain amount of movement however, where there is significant movement or there is a failure in the fabric or construction of the building, this movement may result in serious damage.

If you see any concerning faults or cracks in your home, or a property that you’re looking to purchase, you should seek professional guidance to determine whether there is a more serious problem present.

Our surveyors are trained to spot signs of subsidence issues and structural damage.

Cracks can be key indicator of issues in the structure of the property or problems with the foundations, but they can also be purely cosmetic. While all cracks should be monitored, how can you tell if a crack is serious or not?

A good gage for assessing whether a crack could present a serious issue is the size and thickness of the crack:

• Fine or hairline cracks: Cracks in the paint or plaster below 1mm thick can be viewed as negligible, often accredited to ‘settling’ or ‘snagging’ issues, especially in new homes.
• 5mm or under: Rarely a marker of larger issues, they will often present vertically or diagonally chiefly in the plaster and don’t present a threat to the structural integrity of the property. These cracks are easily filled and may just require ab small amount of repointing.
• 5-15mm: It is advised to seek professional building work as this may require brickwork, more extensive repointing or masonry work patched by a mason.
• 15-25mm: Cracks of this size are often an indicator of structural damage and it is strongly advised to arrange for an inspection and work to be carried out by a professional. You may also notice leaning or bulging walls and a distortion to window and door frames. Cracks above windows or doors could signify structural faults such as a failure in the lintel.
• 25mm or more: A clear sign of serious structural damage, these cracks require immediate attention. This may involve major repair work potentially including underpinning and a complete rebuild of sections of the property.

Structural or foundation cracks will typically present in a vertical or stair-like crack to the exterior walls following the mortar or the brickwork, often visible from both inside and outside of the property. They indicate of issues in the foundation or where the load bearing walls are no longer able to hold the weight of the structure due to a fault in the construction or potential subsidence issues.

Subsidence occurs where the ground underneath a property moves downwards causing the buildings foundations to become unstable and potentially sink. This movement can create large cracks to the exterior and interior walls, which are especially prevalent around windows, doors, and towards the corners and foundation of the property. Misalignment of joinery and masonry such as windows and doors may also be indicative of large movement.

It is important to monitor and investigate cracks that emerge at the property, particularly where there is growth in the cracks overtime as subsidence related issues have the potential to destabilise the construction of the property entirely.

Common causes for subsidence include:

• Collapsing mineshafts, tunnels, or caves
• Damage to or from faulty construction of the property’s foundations
• Damage from tree roots where they are planted too close to the property line
• Soil shrinkage occurs where the volume of moisture within the soil changes, this can be particularly common where there is clay soil which is susceptible to shrinkage during hot weather