What is Water Ingress and why is it a problem?
Water or moisture penetration from the outside of a building to the internal areas is generally referred to as water ingress. Water ingress can present in a variety of ways. A commonly known type is rising damp, which is often found in heritage buildings due to the breakdown of the original damp proof course over time. Entry through the building fabric above the ground can be caused by surface absorption, penetration through windows and doors or defective roof plumbing. Sub surface ingress via defective drainage can lead to structural failures such as settling foundations and wall cracking as a result of subsidence. Defective waterproofing membranes allow moisture to escape from wet areas leading to framing rot and concrete cancer. The list goes on.
Whilst minor leakage due to water ingress may be only a nuisance to some, many of the defects that can arise due to water penetration over a longer period are deemed to be ‘major defects’ due to the destructive outcomes such as structural degredation of framing or problems such as mould which may render the building uninhabitable.
A major defect means;
(a) a defect in a major element of a building that is attributable to defective design, defective or faulty workmanship, defective materials, or a failure to comply with the structural performance requirements of the National Construction Code and that causes, or is likely to cause:
A major element of a building means:
(a) an internal or external load-bearing component of a building that is essential to the stability of the building, or any part of it (including but not limited to foundations and footings, floors, walls, roofs, columns and beams), or
(b) a fire safety system, or
(c) waterproofing, or
(d) any other element that is prescribed by the regulations as a major element of a building.”
How common are Building Defects?
Unfortunately, the occurrence of general building defects is quite high. Research conducted by UNSW in 2012 found that 72% of Apartment blocks in NSW have building defects and over 80% of apartment blocks in NSW built since 2000 have building defects.
Older buildings present different issues. Heritage buildings were built using lime-based mortars, the characteristics of which, differ to those of cement-based mortars. Lime based mortar is more pliable medium than cement mortar and older building can adjust to slight movements in foundation material without apparent cracking. Lime mortars and renders also allow heritage buildings to ‘breath’ where as cement mortar and render traps moisture within. Applying a cement-based render or repointing lime laid masonry with cement-based mortars will lead to accelerated deterioration of the masonry material.
Applying modern materials to heritage buildings often leads to defects such as rising damp, falling damp and mold build up. The abutment of additions to existing heritage buildings can also be an area of concern with sub soil damming and compromised ventilation leading to foundation failure, cupping floor boards, timber rot and mould issues.
What are the most common building defects?
Buildings are exposed to driving rain, blistering sun, freezing cold, ground movement and just like people, buildings age. Sometimes they are poorly built, badly designed or inadequately maintained. And as a result, it would be difficult to locate a building that didn’t present some type of defect. But, not all defects are immediately problematic. Being able to identify a building defect is just as important as being able to assess the current or future impact of the defect.