You'll be extremely lucky to find a property with no cracks whatsoever; 90% of the time, these cracks will look worse than they actually are. However, it's well worth paying attention to them. Subsidence cracks will be more obvious and will typically start from the base of the property. Not only will these cracks be visible on the outside, but they will also be evident from the inside. It's always possible that the ground below has reached a point where it is no longer sinking, and in this scenario, it's often as simple as stitching the brickwork back together and repointing with mortar. The best way to determine if the ground has settled is to fix a small piece of glass (approximately 100mm x 50mm) over the crack using a building adhesive, and then monitor the situation for six months to see if the glass breaks. If there is still movement after six months, this could indicate a need for underpinning.
Also, have a look for chimneys. If you see a chimney on the roof, check to see if the rest of it is still in place. To do this, check the rooms below; you should see the chimney coming down through the ceiling. Be aware that on certain properties, these can also run down the outside of the building, or, in rare cases, between the properties.
Make sure this continues down into the room below
If the chimney stack has been removed below, this will be another reason for structural cracks. Many people remove these themselves and pay no attention to the structural supports that are needed. It is well worth sticking your head in the loft to see if there are supports.
Clay-rich soils can absorb a lot of water, much like when you fill a sponge; it will appear smaller when wet than when dry. The same can happen with clay.The water table underground can constantly change. Whether that change is due to wet or dry weather, broken drains below the surface, or cutting down a nearby tree that has been absorbing water, various factors can affect the conditions beneath your feet.New builds today accommodate this by incorporating compressible materials in the footings, which help to alleviate clay heave. In older properties, you won't find this compressible material used; however, in most cases, the house remains standing and unaffected.A survey report indicating that ground stability is high is not necessarily a reason for alarm. If you look at the map below, you will see the areas most affected in the UK. You can read about this in greater detail. here
