Most old buildings move to some degree during their life, but this movement may not be a problem. Cracks do not necessarily need to be a cause for concern. As most period houses differ in their construction to modern houses they can tolerate a degree of movement without any serious problems.
When to consult a specialist
Movement in old buildings can be seasonal, dictated by temperature changes. It could also be historic – i.e. there is evidence of past movement but there is no movement now. Only when the movement is ongoing and threatens the use or safety of the structure should you be concerned.
If the movement is suspected to be ongoing then a structural engineer who is familiar with old buildings should make an inspection (see Finding Professional Help). The structural stability of an older house is dependent on how it all fits together. If the connections between the various components - walls, floors and roof structure - are unstable or inadequate then the building is vulnerable to disproportionate damage.
What causes structural movement?
There are several issues that can cause structural movement.
- Decay: If water has got into the fabric of your home it could cause some form of material decay – rotting timbers, crumbling bricks - that could compromise its structural stability.
- Temperature: Problems can also occur with materials moving at different rates through changes in temperature - this can give rise to differential movement and distortion.
- Foundations: Houses were usually built with simple shallow foundations and can be vulnerable to settlement over a long period. As older houses tend to be more flexible than modern buildings, they can often accommodate this movement without any problem.
- Alterations: Structural problems can also occur as a result of alterations that affect the overall stability of the building. Common problems include partly removed chimney breasts, overloaded floors, roof structure alterations for doorways or windows and cutting into floor joists to accommodate services. Often these types of problem can be hidden and require some investigative work.
Character and crookedness
Often distortion of the structure can be part of the character of an older house. Unless the structural stability is in question when safety margins have been eroded by continual movement then it is best to leave well alone.