Mar 2020 TELL-TALE SIGNS OF CONCRETE FOUNDATION DAMAGE, THE CAUSES AND RISKS
One of the leading causes for major structural damage to homes, schools and places of business, learn to identify tell-tale signs of distressed foundations, what is causing this to happen and the risks associated to damaged concrete foundations.
Much in the same as a chain is only as strong as its weakest link, structures and standalone fittings such as boundary walls and other applications placed on concrete foundations, are only as steadfast as the foundations they are built on.
While water or ongoing exposure to moisture is typically the primary cause of damage to any concrete installation, there are a few other factors that have a hand in causing damage to concrete foundations that include;
- Subgrade Soil Type and PreparationTypically clay type soil is guilty of becoming expansive both by swelling and contracting depending on the water content present. Comparatively sand type soil can lose traction and sift with time creating an equally unstable surface for long term foundations. While soil type should always be a consideration for sound foundations, so should the preparation of the foundation’s subgrade. Using an infill material from a good quarry is an alternative if insitue material is not sufficiently stable for a proper foundation, subgrade should also be effectively compacted to prepare a stable and compressed surface on which to place steadfast foundations.
- Improper water drainagePooling in and around foundations, if rain water or irrigation run off is not adequality drained away from foundations, ongoing exposure to water that is absorbed into the air chambers of concrete will freeze and expand, thaw and retract forcing the concrete to become brittle and distressed over time.(not common in South Africa except can occur in very cold/high altitude places like Lesotho)
- Extreme Weather Conditions including floods or droughtsAlso influenced by the presence of water or moisture in the concrete matrix, extreme weather can have a negative impact on concrete. Whether too much moisture, freezing temperatures of extreme heat and dry spells that can evaporate moisture, each of these conditions eventually erode concrete foundations.
- Seismic ActivityIn areas of increased seismic conditions, earthquakes can wreak havoc on concrete foundations as the surface of the earth shifts, shudders, rolls and shakes concrete installations during an episode. Damage is not only cause by movement originating from beneath the surface of the earth, but the shift in pressure of the construction on top of the foundations.
- Surrounding Influences such as tree roots and other subgrade disruptions (like big boulders in surrounding soft sandy soil).Exerting pressure on surrounding soil or directly intruding on concrete foundations, the roots of large trees are known to cause some significant damage to concrete foundations. Leaching moisture from soil and subgrade, uprooting slabs and even bursting underground water pipes flooding foundations, tree roots should always be a consideration when planting to nearby construction. (best to involve a horticulturist)
Regardless of the cause, damaged concrete foundations compromise the integrity of the structure in question while also having a negative impact on the property’s value and cause unsightly blemishes like cracks and surface warping even requiring to demolish buildings with severe foundation damage, to name a few.
While all new construction settles into place with time, if foundations are insecure and of not sufficient size or strength and under duress, there are very apparent signs to tell foundation issues apart from slight and organic shifts.
The most obvious signals that foundations are unstable are;
- Cracked bricks
- Misaligned doors and windows
- Cracked or uneven floors
- Wall rotation or leaning – off plumb
- Splits in masonry where brick separate form mortar
An alarming amount of homes and other structures are built on inappropriate subgrade and damaged foundations that can cause costly structural damage and more concerning compromise the structural integrity making the building a hazard and unsafe to occupy.
While hairline cracks in concrete foundations are normal and mostly unavoidable given the effect of freeze thaw expansion and contraction when exposed to water or moisture, experts estimate that if a crack is broader than around 3 mm, this could be a good indication that concrete foundations are in need of a foundation inspection and repairs by a foundation specialist. Foundation repairs are extremely difficult and not always successful, besides it being very expensive.