Cracking can occur to many different building components for many different reasons. Cracking is expected to some degree, its whether or not the cracking is structurally significant which matters most. A few common causes are below and some ways to prevent them.
Cracking can occur through:
- Thermal movement. (Expansion and contraction of materials from heat and cold). When building materials are installed without a gap or movement joint they will crack when the building component expands or contracts.
Very common in external tiles, internal tiles near windows (sunlight), internal tiles with sub floor heating, external pavements and external poured concrete. Can be prevented with adequate compaction of the substrate, proper thickness of the concrete slab or pavement, re-inforcement, control joints and isolation joints. Not normally a structural defect, however cracked tiles and grout in wet areas can lead to damage to the waterproof membrane and escaping water can cause structural issues.
- Footing or foundation movement.
Common to houses where poor compaction has been achieved or reactive soils are in contact with the footings. Can result in stepped or vertical cracking to brickwalls, cracked plasterboard ceiling and cornice. Can be avoided by proper substrate preparation, isolating reactive soils from footings and slabs, isolating adjoining building components (movement joints). Can often be a structural concern especially when windows / doors are binding or one side of the wall is offset from the other at the crack or the cracking, or the external brickwork is cracked (allowing moisture in)
- Differential building movement.
Different building components expand and contract at different rates. Timber flooring will swell in moist or humid environments, bricks will grow over time, slabs will settle, unseasoned timber will shrink, metal will expand and contract with changing temperature. Buildings must be constructed to allow for this expected movement.
In summary buildings will crack because they are expected to. The location of the crack may mean a structural defect which poses a risk of damage to the building, or to people or to the health of the occupants and will require rectification.
A report from a registered building inspection company will identify what has caused the cracking and if it could have been avoided by better construction practices If the building is less than 6 years old or is covered by an extended structural warranty then an expert witness report from us will assist you getting the builder to rectify the defect.