Subsidence is where the ground supporting a buildings foundation literally begins to sink causing the building to move, there are several causes for this ground movement and is most common in clay soil which shrink and swell according to their moisture content. If you have or suspect subsidence you should not be too alarmed as it can be rectified in most cases. The majority of the causes are beyond the control of the home owner; however you should look out for cracks more than 3mm wide in the external walls or the progressive or sudden widening of existing cracks. Doors and windows getting stuck can also be a sign of building movement.
If you have or suspect you may have subsidence a PCDS chartered structural engineer can arrange for a site visit to come and asses the property and provide a report which will identify the potential cause if movement and record further investigations or remedial action as required. If subsidence is not the cause of the cracking or movement the engineer will find out what the cause is and advise accordingly. PCDS know that underpinning existing foundations is expensive and underpinning will only be advised if absolutely necessary.