Seeing cracks in the foundation is often considered normal wear and tear. Cases remain rare where the integrity of the building will be questioned and it is not always a construction defect. Sooner or later, a house may experience a risk of cracks in its foundations but it is essential to be able to distinguish more serious situations, which will require urgent and sometimes complicated work, from less alarming cases.
Possible causes of foundation cracks
A crack can have many origins. The origin of cracks in foundations can be traced from:
- Clay soil
- Defective backfill
- Poor drainage
- Water infiltration
- Presence of pyrite or iron ochre
- Landslide
Soils are alive, they move, they are friable, sensitive to vibrations, climate, bad weather, etc. In comparison, the footing and concrete walls of a house’s foundation can crack under heavy stress. The house rests on a concrete footing or rubble. If the ground sags, the whole house follows. A settling backfill, a soil that retains water or that moves can cause the concrete slab to subside. Other causes have mineral origins. In areas where the soil is ferrous and when there is water and air present, ochre deposits are formed, orange in color like rust, which can end up blocking the French drain. The presence of pyrite in the backfill can cause swelling of the stones and cause cracking of the slab and/or foundation walls. These problems vary greatly from region to region. It is also sometimes combinations of different origins that can aggravate the situation.
Foundation cracks: in which cases is it serious?
A crack can be active or passive. An active crack is a crack that evolves more or less quickly over time. It can lengthen, spread or multiply. If the deterioration is rapid (visible over a few weeks or less than a year) urgent intervention will be necessary. The structure and integrity of the foundation could be questioned and the house could risk collapse. Foundations may no longer fulfill their main function: to keep the house safe in the ground. It will therefore be necessary to install piles on the foundation, so that the load of the building is stabilized on a stable ground, called bedrock. Click here for more information on pile installation.
However, not all foundation cracks are alarming, nor related to a hidden defect, nor to a construction defect.
