Where a single cause or point of water entry has been identified, carrying out repairs that target and remedy that specific cause may be a valid repair option. In effect, a localised repair is a 'like for like' replacement in which the repair matches existing. Localised replacement will not be a valid option if the damage or failure is widespread, for example, if the failure was not caused by the cladding failing, particularly for monolithic-clad dwellings. Obviously, this will be a far more realistic proposal where cavity construction has been used originally.
Before committing to a localised repair, the designer should determine:
- whether the building condition and remediation report identified the building’s weathertightness risk and provided sufficient evidence that, given the risk features, the remainder of the building is dry and is likely to remain dry
- whether it is certain that there is a defined single localised point of entry
- whether the timber treatment level is verified at H1.2 or better (If framing is untreated or treated to H1.1, the risk of future problems is considered greater. Also, current requirements ask for a minimum of H1.2 treated framing for direct-fixed claddings.)
- whether there is a risk of water entry in the future (and, if so, what the designer’s liability will be)
- whether there are outstanding issues required for the building to get a Code compliance certificate (if so, a localised repair is unlikely to resolve this)
- whether the owner is aware of the on-going maintenance requirements to ensure the continued integrity of the cladding system
- whether the repair will work.
- Cost will be significantly lower than a partial or full reclad.
- The dwelling may be occupied during repair work.
- Windows generally remain in place.
Drawbacks that need to be addressed when an isolated repair is proposed:
- With this option, because there is always the risk of a future failure elsewhere in the building, it is essential for the designer to document the strategy and reasoning for adopting this repair option. It may be difficult to legally limit liability under the Consumer Guarantees and Fair Trading Acts.
- There must be certainty that the problem is isolated. The figure below shows a simple leak from the bottom corner of a window but significantly different areas of damage because of the location of the window. Also, while only one window may be leaking, there is a risk that others will leak in the future. The key question for the drawing on the left is: What is the likelihood of the same failure occurring with the remainder of the windows – is there one clearly identifiable individual fault that caused that particular window to leak?
- Is there a logical point where the repair can be started and stopped, for example, is it logical or possible to extend the area of repair to a building feature such as a corner or cladding junction?
- Can the repair be seamlessly integrated into the existing by ensuring that:
- Defects elsewhere in the building may remain undetected.
- It will not remove the risk of future problems.
- It may be difficult to insert new flashings.
- There needs to be an alternative strategy should the assessment prove wrong and damage is more extensive.
- It may be difficult or not possible to obtain a building consent, particularly where the failure was due to the original construction not meeting Code requirements, as the original construction may not be aligned with the details given in E2/AS1 current at the time of construction.
- It is not likely to overcome any stigma associated with a leaky building even though the repair is isolated and satisfactorily repaired, particularly in a monolithic-clad dwelling.
- The repair may cause damage to sound areas of the building.
- Isolated repairs do not give the added protection of a cavity where cladding is replaced where the existing cladding is installed in a face-fixed situation.
- There is no ability to address improvements such as increasing the level of insulation, removing at-risk design features or site treating existing timber.
Examples of cladding failures from a single leak
The area of the face of a building that may be affected by a single leak will depend on where the leak occurs. Both these diagrammatic examples could be a single leak from the bottom corner of a window, but the example on the right shows the affected area of wall is greater. With the two-storeyed building, there is also the risk of damage to the floor joists in the area below the window leak.
Examples of when an isolated repair may be considered appropriate are:
- a leaking flashing around a chimney that has been framed and clad
- a single roof penetration such as a pipe or roof light
- leaking metal roof fixings
- the end of an apron flashing that was installed without a stop-end
- a single isolated penetration such as a pipe or dryer vent installed through the cladding
- where a single window or door has been wrongly installed – all other windows would also need to be checked; the location of the window within the wall area is also important
- a single waterproof deck where the affected area of cladding can be determined – this is likely to require some alteration to walls above the deck to allow new membrane to be properly installed and may involve recladding the face of the building that contains the deck and the detailing of the junctions with the existing cladding to ensure future weathertightness
- repair of cracked joints in fibre-cement (provided framing behind is sound and dry)
- where cladding is installed over a cavity that has been properly constructtd.
Updated: 9 September 2014