“Cracking of masonry buildings can be an area of great concern and, whilst these indications are not the first step in total disintegration, many are unaware of this” says Archicentre Australia director Peter Georgiev.
“Mostly cracks require cosmetic treatment only. The majority are not indications of grave structural damage. Remedies can be as simple as watering the garden a bit more or less, or just waiting for the season to change” he says.
However it can be valuable, if only for peace of mind, to be able to recognize and evaluate the type of cracks – as there will at least be some logical basis for deciding which method of correction may be appropriate.
Mr. Georgiev says “Unfortunately lack of knowledge can lead to the adoption of unnecessarily expensive treatments which may be suggested by firms biased in favour of using their own patented and profitable ‘cures’.”
An Archicentre Australia architect can assess the particular nature of individual buildings including houses, apply Standard definitions of cracking, and act as a filter in cases where more thorough investigation by a geotechnical engineer and structural engineer are required.
The on-site assessment can determine the nature of cracking – usually vertical, horizontal, cogged, stepped or a combination.
How much foundations move depends on the type of rock or soil and how that type is influenced by changes in moisture, temperature and imposed loads. The movement on the foundations is rarely uniform over the whole of the building site, and different movement under different parts of the footings creates stresses in the walls resulting in cracks.
Foundations are usually classified as either reactive or non-reactive to changes in their moisture content. Reactive soils are typically clay soils, but also include the “black soil” and “black earth” found in many states especially South Australia. All of these are plastic soils, shrinking and swelling rapidly as their moisture content decreases or increases. For example, reactive clays may swell and retain moisture when saturated which can cause deformation, particularly in modern houses with concrete slab floors, and shrink and collapse when water is removed from them by excessive evaporation or by the action of trees. Non-reactive soils are such soils as rock, gravel, shale, phyllite or sand which volume does not increase or decrease depending on the moisture content.
The greatest damage occurs when trees are planted after construction. Contrary to popular belief, it is rarely the growth or uplift of the tap roots to big trees which disturb the foundations. The damage is done by the plants extracting considerable quantities of moisture from the soil which reduces the volume of the soil, causing footings to subside in that area and cracks in the masonry or timber frame to appear.
While drying out of soil by trees is the most common reason for cracking in masonry, some clays are also very susceptible to drying out by direct solar radiation. The northern facing wall is the most likely to be affected and stepped diagonal cracking is the most common symptom, usually occurring at the north east and north west corner of the building.
Tips around masonry cracking include:
- Suggest to not plant trees or allow them to exist close to masonry buildings and limit their heights unless their roots are discouraged or contained in some way as in the systems described.
- Recommend the garden and lawns around the building be kept evenly damp throughout the drier months. Don’t neglect one side of the building just because nothing much grows in that area
- Encourage regular checks of existing drains, down-pipes, guttering and service piping to ensure no leakages occur over the life of a masonry building
- Never jump into underpinning works – seek architectural guidance and a balanced brief to an independent geotechnical engineer and structural engineer.
Archicentre Australia director Peter Georgiev says engaging an Archicentre Australia architect can provide peace of mind and save customers the anxiety not to mention cost of potential expensive and often unnecessary remediation.
For more information go to www.archicentreaustralia.com.au
This media release has been written and distributed by:
Peter Georgiev, Director
Level 1, 9 Strathalbyn Street,
Kew East, VICTORIA, 3102
Phone: 1300 13 45 13 | 03 9859 9950