Older houses move.
Many older Queensland homes have been moving slightly with changes in seasons, soil moisture and weather conditions since the day they were built.
That does not automatically mean there is something structurally wrong with them.
The important questions are whether the movement is within the normal behaviour of that particular building, whether it has changed, and whether there is an underlying problem that needs attention.
Older Houses Were Built Differently
Traditional Queensland houses often used construction materials and finishes that tolerated movement quite well.
Timber framing, timber floors and traditional wall linings could accommodate small movements without making every change obvious.
Owners also expected houses to require ongoing maintenance.
A small amount of seasonal movement, minor cracking and occasional adjustment was part of owning an older building.
Renovations Can Make Movement More Visible
An older house does not stop behaving like an older house simply because it has been renovated.
Renovation work can actually make movement more noticeable.
For example:
- flexible or jointed wall linings may be replaced with smooth plasterboard;
- walls may be removed and replaced with beams;
- open-plan areas may change the way the structure behaves;
- new finishes may show small cracks more readily;
- old stumps or supports may remain beneath a newly finished interior; and
- new and old parts of the house may respond differently to seasonal movement.
This can result in a house looking newly renovated while the original footing and framing systems continue to move in much the same way they did before.
Seasonal Ground Movement
Many houses in Queensland are founded on soils that change volume as their moisture content changes.
Wet periods can cause some soils to swell, while prolonged dry periods can cause them to shrink.
Older houses supported on stumps, shallow footings or mixed footing systems may respond to those changes with small differences in floor level and wall movement.
The important issue is whether the movement is relatively stable and seasonal, or whether something has changed and the building is behaving differently from before.
A Storm Does Not Automatically Cause Every Crack That Appears Afterwards
Cracking is often noticed after heavy rain, storms or flooding because homeowners understandably look more closely at their property after an event.
But timing alone does not establish cause.
A crack visible after a storm may be:
- new damage caused by the event;
- older cracking that has become more visible;
- seasonal movement associated with changing soil moisture;
- movement caused by drainage or water leaks;
- the result of deteriorated structural elements; or
- part of the normal behaviour of an older building.
Determining the cause requires looking at the building, the site and the available history rather than relying on when the damage was first noticed.
Drainage Is One of the First Things to Check
Good drainage is important for both old and new houses.
Conditions that can contribute to building movement include:
- stormwater ponding beside or beneath the house;
- overflowing gutters;
- downpipes discharging near footings;
- broken stormwater or sewer pipes;
- leaking plumbing;
- poor ground falls;
- erosion around supports; and
- large changes in vegetation close to the building.
Before considering expensive foundation work, it is often sensible to understand whether water management around the building can be improved.
For more information, see our drainage and stormwater inspection advice.
Older Houses Also Need Maintenance
Not all movement is caused by soil.
Older buildings may also develop problems with:
- decayed timber stumps;
- corroded steel supports;
- damaged bearers and joists;
- termite damage;
- loose or deteriorated connections;
- settled packing over stumps; and
- previous alterations that changed the load path through the house.
Where a floor has become noticeably uneven, repeatedly requires adjustment or has changed relatively quickly, the cause should be understood before simply levelling it again.
Do Cracks Mean the House Is Failing?
No.
Cracking is evidence of movement, but the significance depends on much more than crack width alone.
When assessing cracks, we consider things such as:
- where the cracks are located;
- their pattern and direction;
- whether they are changing;
- whether doors or windows are sticking;
- whether floors have moved;
- the building materials;
- the footing system;
- site drainage;
- the age and history of the house; and
- whether there are signs of deterioration or structural damage.
A small crack in one location may be insignificant while a similar-sized crack somewhere else may deserve closer investigation.
When Should You Be More Concerned?
It may be worth obtaining engineering advice where:
- cracking is increasing noticeably;
- new cracks continue to appear;
- doors or windows have become difficult to operate;
- floors have developed noticeable slope or movement;
- stumps, posts or structural members are deteriorated;
- there has been erosion, flooding or ground loss;
- part of the house has moved suddenly;
- cracking is associated with a significant storm, impact or other event;
- renovation work has exposed unexpected structural conditions; or
- there is disagreement about the cause of the damage.
Should an Older House Be Underpinned?
Not simply because it moves.
Major footing upgrades can be expensive and disruptive, and they should be considered only after the cause and significance of the movement are properly understood.
In some cases, improving drainage, repairing deteriorated supports or correcting a local problem may be more appropriate than undertaking major foundation work.
For more information, see our guide to underpinning and foundation repair.
Repairs After Storm or Flood Damage
Existing movement is particularly important when repairing an older house after an insured event.
New plasterboard, paint and finishes may crack again if the underlying structure continues to experience normal seasonal movement.
This does not necessarily mean the repair was defective or that all later movement was caused by the original event.
Understanding the building’s pre-existing behaviour helps owners, insurers and repair builders develop realistic expectations about the repair.
Old Houses Can Keep Performing for a Long Time
An older house does not need to behave exactly like a new concrete-slab house to be structurally satisfactory.
Many older Queensland houses have performed successfully for decades while experiencing small amounts of seasonal movement and requiring normal maintenance along the way.
The objective is not necessarily to eliminate every movement or every hairline crack. It is to recognise when the behaviour is normal for the building and when something has changed enough to warrant investigation.
Concerned About Movement in an Older House?
If an older house is cracking, moving, developing uneven floors or behaving differently from the way it has in the past, send us the property address, photographs and any available information about its history.
Historical photographs, previous reports, renovation drawings and information about when the movement was first noticed can all be useful.
We will review the information and let you know whether a structural engineering inspection is likely to assist.