There are several different reasons that cause cracks in buildings.
Earth movement
The foundations of a building should be designed to evenly distribute the weight of a building onto them. Cracking in foundations occurs when they become uneven. This can be due to shifting of the ground that they are sitting on.
Lateral support – If there is building work happening on the site next door excavating for the foundation may cause a shift in the ground.
Subterranean Watercourse – Any local leaking drains, main or burst pipes can cause water to sift through the ground. These can affect underground rivers and may cause erosion in the foundations.
Mine shaft – It is hard to locate these and they are known to collapse very easily thus shifting the earth that surrounds them.
Precautions
Buildings that haven’t been specifically designed to withstand any of these causes can suffer severely even though the national coal board may compensate for damage caused by mining. The following precautions should be taken in order to restrain cracking in buildings.
- Special raft foundations
- Heavy piers between openings
- Compartmentalizing the building
- Increasing the falls on gutters & drains
Ground conditions
Consolidation of soil – this process can happen over a number of years where for example field ditches get filled and are camouflaged into the rest of the consolidated soil. This means that a foundation strip would need to span this ditch, otherwise it may fail.
Clay - contains the properties to expand and contract when wet and dry. This should be looked at carefully before laying foundations as change in the clays consistency can cause foundation damage. One should ensure that trees are a far enough distance from the building as they ensure there is plenty of moisture in the ground.
Frost – Water seeps into cracks and expands when frozen. In poor weather conditions water frozen under ground can uplift paving stones and concrete floors.
Temperature changes – most modern buildings are designed to contend with climate change. Expansion joints are incorporated at specific points of the building to accommodate for such situations. However if the break is incomplete damage may occur.
Moisture – Drying of concrete walls & floors etc are usually subject to superficial cracks as they contract when they loose moisture. These are not so important to the integrity of the building.
Overloading
Another common cause of cracking in buildings is overloading the weight the foundations can bare e.g a new floor or roof extension. Also implementing a new door or window into an existing wall may may cause cracks in the wall if for example the lintel was not correctly chosen to distribute the weight of the wall above it.
Corrosion
Corrosion of wall ties can occur once the galvanized steel has lost its zinc coating. When a few of these break horizontal cracks will appear in the wall.
Other reasons for cracks in buildings are sulphate attacks, decay in timber and generally poor design and construction.
