Don’t Panic when your house cracks!
Most homes develop defects such as cracks. Old and new homes can develop cracks in foundation footings and walls caused by climatic and physical factors.
However, it is worth getting to the bottom of what is causing the defect. A crack is the visible symptom of a possible problem or defect causing the crack.
What causes cracks?
New homes
In new homes, settlement may cause minor cracks. Normal foundation settlement occurs when the underlying soil compacts because of construction on previously undisturbed soil, changes in soil conditions and moisture. Typically small, hairline-sized cracks may indicate a minor settlement, expansion and contraction, or changes in a season or cycle.
Usually, these defects, though often unsightly, are not structurally significant.
Thermal movements between different materials
Different materials such as timber, bricks, steel, concrete etc. have different linear expansion coefficients. In other words, the differing materials contract and expand differently. This causes stresses in structures where they are combined and may cause cracking to form. The best way to combat these defects in plasterwork is to provide a joint between the different materials.
Older homes
In older homes, changes in climatic conditions can affect the structure. Houses move with the climate. Heat and moisture will make them expand, and cold and dryness will make them contract slightly. This movement is normal and in most cases will not cause cracking. Unusually hot or cold spells can increase the structural expansion or contraction which may cause cracks.
The rise or fall of the water table in very dry or wet conditions can also affect the house’s foundation footings.
Changes in the house’s surroundings, such as the placing of new gardens or the planting and growth of trees, can change the moisture content of the soil supporting the foundation footing.
The leaking of old water or sewer pipes in the ground can go unnoticed and change the moisture content of the soil under the floor and foundation footings causing subsidence of the foundation footing and filling material under floor slabs. Similar defects can result from leaking showers and baths.
Dripping hose taps and dripping water pressure regulators near foundations and irrigation systems spraying onto your walls and foundation footings can cause subsidence and cracks.
The pooling of rainwater around your house or close to the foundation footings will also affect your house’s structure. Make sure the ground slopes away from the house.
Additions to the home such as newly paved areas and new rooms can also affect the moisture content of the soil. Older parts of the home’s foundation footings and structure can be affected.
Vibrations from traffic or blasting, particularly if your house is over a ridge, can cause cracking.
Homes built above former mine workings, landfills, and possibly filled ground can be most susceptible to structural defects.
There are so many more reasons that may affect the foundation footing of a home. Always try and look for the reason that a crack develops. Be careful about what you change around your house!
How to deal with cracks?
Plaster cracks
Where they are superficial (less than 5 mm in width), use good-quality fillers and paints. Fine cracks (less than 1 mm in width) should be sealed by painting over them.
Simply redecorating should be enough to mask most superficial cracking in plasterwork.
Most hardware and building materials stores sell fillers and paint filler combinations, which will help to repair smooth surfaces.
Structural cracks
Cracks in brickwork are a different matter. Climatic conditions acting on flaws within the brick can cause cracks. They can also be caused by any of the reasons mentioned before.
Look out for them around window and door frames. This may be symptomatic of extra stress being placed on the structure.
If doors begin to stick there may be a serious underlying cause. This is especially so if they stick when opened.
Plastered brickwork
If the crack has resulted from a movement which continues after you have filled and painted over the crack, you should reinforce the wall across the defective area. Remove the plaster approximately 75 to 150 mm on each side of the crack and remove all debris and dust. Nail a strip of expanded metal or chicken mesh, the width of the area, to the wall and wet it. Force the plaster into the area and work it to match the surrounding plastered area. Allow a drying period to repaint the wall corner to corner.
Face or semi-face brickwork
Cracks in face-brick walls pose a different challenge! Here you will remove the mortar joints across the crack for about 50mm deep and between 150mm and 200mm on either side. You then drill holes another 50mm deep one on each side and insert epoxy and a reinforcing bar with the ends bent up in a U shape into the holes. You then repoint the joints with mortar.
Alternatively, you can remove the brickwork around the crack and re-instate the removed brickwork if you can find the same or similar face bricks.
If you find an external crack in your walls and leave it, the defect will get worse. Furthermore, water is going to use the crack as a way to get into your house.
To avoid future or further damage repair all cracks that can let water into the structure or are exposed to moisture.
If a crack suddenly forms larger than 5 mm in width, it needs immediate professional attention. Moreover, you need to investigate and eliminate the cause of the crack!
Finally, before you buy a house, ensure you have commissioned a home inspection for possible problems.
Prevention is better than trying to find a cure.
Inspected Once, Inspected Right!®
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