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Building? Is that crack still live?

big crack in wall resize

There is no user manual for all aspects of homeownership, from moving, to taking occupation and to maintaining and understanding common and uncommon defects. Albert van Wyk has more than 38 years’ worth of building experience and has put all he has learned into a concise, easy-to-use reference book entitled, The Proud Home Owner. He has granted HomeTimes exclusive access to republish portions of his book to help homeowners make better decisions around buying and selling, as well as maintaining their properties.

Is your house cracking up?cracked house resize

When anybody sees a crack in a wall, they think that it is the worst thing that can happen to a house. This is not necessarily true, because it is not always possible to prevent all cracks. One reason is that it is difficult to control the moisture changes in the soil around the house which can cause movement and result in cracks. There are cracks in all buildings, some are minor and some which require expensive repairs.

A crack in a structure will happen when there is differential movement between the elements, e.g. between the bricks, between the soil and the concrete, between bricks and concrete, steel and concrete, and wood and bricks.

Materials can suffer initial shrinkage and/or subsequent expansion and contraction after installation. Different matrials like concrete, steel, wood, bricks, plaster and tiles are all combined in the building of a house in soil, and it can be expected that they will all settle differently which could result in cracks.

The building is also subjected to rain, hail, wind and tempreture changes.

The southern side of the building is colder than the northern side. Strong wind can cause cracks in high gable walls.

The responsibility of the contractor for a new house

The contractor must honour the Standard Home Builders Warranty which is given by the NHBRC that includes the following:

  • The builder must rectify, at his own expense, all latent and patent defects manifesting during the construction phase of the house.
  • The builder must rectify, at his own expense, any deficiency related to workmanship and materials during a 90-day period from date of occupation.
  • The builder must repair, at his own expense, any roof leaks that occur during the first 12 months after occupation.
  • The builder must rectify any latent or patent defect in respect to the foundation, superstructure and roof structure for a period of five years after date of occupation.

The responsibility of NHBRC

NHBRC will, during the five-year period, at its own discretion, rectify defects where the builder is unwilling or unable to rectify valid defects.

Albert says: “It is not possible to prevent all cracks”

Cracks can be divided into 2 main categoriessmall crack

Live cracks

A live crack is one that has not settled yet and is still active. Live cracks are caused by soil movement, either by heaving clay or subsiding soft sandy soil.

If the conditions have not stabilised, then cracking will continue, either with new cracks or the existing ones will open and close during dry and wet seasons.

The cause of live cracks must be addressed in order to solve the problem. Underpinning of the foundation is usually the only solution for severe structural cracks which are due to subsidence.

A crack in a corner, where walls are not well bonded because of poor workmanship, can be fixed by changing it into an expansion joint. Cut a groove through the plaster and fill it with a flexible sealant like silicone, instead of a hard filler, which will accommodate the movement.

Static cracks

Settlement cracks are usually classified as being static, because it happened during the settlement process and they have since stabilised. Cracks which have happened because of the subsidence of the soil below the foundation will also become static and stable.

These cracks can now be permanently repaired because no further movement is expected. A structural crack can also become static after all the movement has taken place. Monitor the gap in the crack before a decision is made on the repairs. Live cracks and static cracks are repaired differently.

Next time: How to identify the cause of structural cracks

For more, and to order your copy of The Proud Home Owner, click here, or visit Gauteng Home Inspections if you’re building, buying or doing maintenance


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