For the purposes of ascertaining the nature of weathertightness related remediation required the client has requested for external inspection, water-ingress testing and documentation identifying weathertightness of the aluminum joinery and cladding (external inspection). EST-02357 and EST-01897 were tendered and accepted by the client.
Upon commencing the external inspection, it quickly came to our attention that the weathertightness concerns presenting internally on many locations throughout the building is not limited to failure of the joinery as previously informed in the Airey Review (2017) pg. 9. Upon which we needed to extend the inspection and documentation process to include an in-depth analysis of the original construction function for the building.
Inspection & Investigation Method
Investigation method was a combination of:
- External and internal inspection,
- Surveying the building internally (via visual and thermal camera) for points of weathertightness failure,
- Research by way of documentation provided by the client (weathertightness package),
- Isolating four specific water-ingress testing sites and conducting water-ingress testing, and
- Tracing water-ingress pathways through moisture meter readings of up to 300mm building material depth.
Externally the joinery and its immediate proximity was inspected
All concrete panels, on every window bay (WB) including their vertical and horizontal joints were examined while being (as appropriate) photographed or video recorded.
Joinery on every WB was closely examined while being (as appropriate) photographed or video recorded.
For the purpose of this documentation, a selection of these photographs has been included as annexure A to this document.
Internally the joinery and its immediate proximity was inspected
All window bays in all levels throughout the building were visually examined.
Locations evident of sever weathertightness failure were recorded by way of thermal imaging and moisture readings of up to 300 mm depth. Those areas were invasively inspected where wall linings were removed and where appropriate minor concrete cuts applied to verify water seepage.
Water-ingress Test Locations & Location Decision Protocol
A complete external inspection of the joinery was conducted.
Visual observation of each level window bays was conducted, where appropriate thermal imaging was utilised and internal locations presenting sever weathertightness failure were identified and invasively inspected.
These locations were then identified as requiring further analysis:
- Original architectural elevations, plans and construction details drawings (1985 Existing façade panel details) were given thorough consideration.
Beyond the visual inspection of the building internally, four internal locations evident of water-ingress were selected due to varying degrees of specificity* presenting in each one of those locations for further data gathering, including moisture readings of 300mm depth and water-ingress testing.
*Location of water-ingress, amount of water or moisture presenting, type and design of pre-cast panel and joint operative. Evidence gathered by way of pre-test thermal imaging and moisture readings of up to 300mm.
Limitations of investigation
Manufacture specification for the joinery and the concrete panels have not been available.
It is highly likely that there may be surface and deep hidden cracks or other water-ingress points throughout the exterior surface cladding which will not visible until all coatings and paint has been stripped and removed during the exterior surface remediation process or at a later date.
It is likely that the exterior surface cladding of the building has undergone previous projects of remediation. The case may be that such remediation work was not properly conducted or has now failed due to the expiry of material durability.
The purpose of this investigation and documentation is to identify areas of material failure of the exterior surface cladding of the building. This investigation or documentation should not be used for the purposes of tendering remediation works. A Remediation Specification should be obtained for the purpose of tendering remediation works. Any form of responsibility, cost over runs, negligence, damages or otherwise cannot be accepted where reliance is placed only upon this investigation and documentation.
The investigation techniques used for the investigation and documentation involved experienced height access technicians and commercial property consultants using a combined approach of visual and invasive investigation along with reliance on the documentation provided by the client and their representative architects.
FINDINGS:
Vertical & horizontal cracks
Vertical and horizontal cracks evident on the concrete panels are a major indication that the building has not met properly life cycle maintenance.
When concrete panels suffer re-entrant corner cracking or the panels protective coating has expired its life expectancy and timely remediation has not been undertaken, then due to the porous nature of concrete facilitating capillary action, moisture enters through these re-entrant cracks as well as the through the surface of the concrete panel.
With moisture entering a larger surface area of the concrete panel, the panels concrete volume can increase during moisture ingress and shrink with the moisture drying placing stress/tension on the panel inducing cracks. With seasonal change, moisture ingress also contributes to accentuated temperature changes in the concrete panel which further accelerate the traveling cracks. All the while the cracks already formed are deepening at which point will allow water-ingress.
These panels are suffering cracks, in various degrees. Some are deeper vertical and horizontal cracks, some deeper cracks at re-entrant window corners. Given the results of the water ingress testing we can confidently conclude that the cracks are attracting a significant volume of water into the concrete wall panel. All the absorbed water and moisture then evaporates creating further differential tension on the concrete which then deepens and extends the network of cracks on the concrete panel.
Fine hairline cracks
The severity of the concrete panel degradation from a remediation perspective are the cracks evident on the surface of the concrete panels. These are very fine cracks in early stage of formation (hairline cracks).
From remediation perspective hairline cracks are challenging to quantify and treat. If such cracks are missed during remediation and left untreated, then due to higher tensile stresses already evident on the concrete panels together with the innate brittle properties of concrete; overtime these hairline cracks will form into larger cracks.
Crazing cracks
Crazing crack are formed where the surface of the concrete is subjected to environmental factors like dirt and carbon dioxide of the atmosphere interacting with the surface of the concrete panel. Crazing cracks are generally not very deep and if attended to without delay they can be remediated with success halting their development into stress related cracking like hairline cracks or re-entrant cracks.
Craze cracks are visually unsightly. However, generally in isolation are not a major serviceability concern as long as long-term maintenance is planned to manage craze cracking halting or slowing its further development.
Spalling and corrosion of reinforcement
Exterior of the concrete panels have several locations of spalling* presenting. It is very likely that the spalling is due to the lack of timely mitigating of water-ingress into the cracks. As it is likely that the concrete panels remain wet and damp allowing water and oxygen particles together with environmental pollutants to provide adequate conditions for electrochemical reactions.
*ASNZS 2327:2017 suggests that spalling of concrete needs to be prevented or where spalling has occurred then its influence on the concrete performance should be considered.