Parramatta Roof Inspection Report Purpose:
Provide a roof condition report to N.C.C 2016 Vol.2, AS 1562.1, AS 1562.3, SA HB 39 2015: The Installation Code for Metal Roofing and Walling as well as manufacturer’s instructions. Provide recommendations to extend longevity.
Inspection Site Gallery
The Following Observations Were Noted:
The roof spans across both buildings are in very poor condition. Several points of ingress are present due to deteriorated and non-compliant installations. Ultimately, all roofing and associated flashing require replacement. Deteriorated and no-compliant items are shown below.
Findings & Recommendations In Blacktown Roof Inspection Report
- Roof sheeting has reached the end of its life span. The roof has suffered numerous repairs in a failed attempt to remedy the ingress. Typically, these failed repairs have resulted in further corrosion of the sheeting. Also note that the roof screw fasteners are also corroded and require replacement.
- Roof sheeting laps are non-compliant to SA HB39 refer 7.15. The lapped sheeting has not been sealed and has resulted in trapped moisture between the sheeting. This has led to widespread corrosion as shown.
- Fibreglass sheeting has reached the end of its life span as shown. The internal fibres have not become exposed and the sheeting is widely deteriorated. Also note that non-compliant fasteners have been used in various locations and are resulting in splitting/ fracturing of the sheeting.Non-compliant fasteners use where the flashing covers the fibreglass sheeting. All fibreglass sheeting requires replacement.
- Numerous Air Condition / mechanical unit penetrations are heavily reliant on tape and silicone which provides no longevity. Several mechanical penetrations are experiencing ingress. Installing numerous cables to a singular Dektite flashing in this manner is noncompliant to Manufacturer’s Instructions.P.V.C gooseneck shrouds should be provided to ensure a long-term
- Eaves gutters are suffering from heavy ponding due to a lack of effective gradient. This results in rapid corrosion of the guttering material. Non-compliant to AS 3500.3 refer 4.5.3. Also note that the Eaves gutters have not been provided any provisions for thermal expansion and will result in failure of the guttering joins. Non-compliant to SA HB39 refer 5.6.
- Several penetrations have blocked the flow of water through the sheet pan and are non-compliant to AS 3500.3 refer 4.4.3. above and Bluescope Manufacturer’s Technical bulletin attached. This results in rapid corrosion of the sheeting.All penetrations that block the flow of water require dry pan flashings with a compliant coverage.
- The roof sheeting has been laid across the dividing parting walls without the use of flashings. As such, the sheeting has not been provided the required number of fasteners throughout these areas as per Manufacturer’s Instructions. Non-compliant to Manufacturer’s Instructions. Step flashings and fire rock wool are to be provided to these areas.
- Large parapet flashings have suffered buckling and deformation due to a lack of provision for thermal variation.Recommend providing sheeted walls cladding to these areas to ensure future
failures are eliminated. Barge cap flashings have not been provided 3-degree fall towards the roof line and have resulted in ponding on top of the flashings. Non-compliant to SA HB39 refer 8.6 below.
- Lapped roof sheeting is non-compliant to SA HB39 refer 7.15. Incorrect lapping of the sheeting has resulted in widespread moisture entrapment and corrosion.
- Fibreglass sheeting has reached the end of its life span and exposed fibres are at risk of widespread ingress.
- Numerous mechanical penetrations are reliant on tape and silicone and are at high risk of ingress.
- Eaves gutters are suffering from heavy ponding due a lack of effective gradient. Non-compliant to AS3500.3 refer 4.5.3 and AS 3500.3 refer 4.4.3 above.
- Several penetrations have not allowed complete drainage of the roof and are heavily ponding. Non-compliant to AS 3500.3 refer 4.4.3 above.
- Sheeting has been laid over the diving walls without the use of step flashings and as such the sheeting has not been provided the required number of fasteners.
- Large wall cladding flashings have suffered from buckling and distortion and are at risk of ingress. Additionally the barge cap flashings have not been provided 3-degrees fall.Recommend providing sheet wall cladding to any areas exceeding 250mm.
Building Code References In Parramatta Roof Inspection Report
7.15 End Lapping
As metal roofing and walling profiles are manufacturers by continuous processes, sheet lengths long enough to cover the roof without lapping may be supplied (subject to the limits of transport regulations). Particular attention is to be paid to the following:
- Should it be necessary, due to handling or transport considerations, to use shorter end-lapped sheets to provide full length coverage, is it preferred that each run of sheets be laid in turn from bottom to top before moving on to the next run.
- The minimum recommended end lap for roof sheeting is 200mm for roof slopes between 1 in 12 (5°) and 1 in 4 (15°) and 150 mm for slopes above 1 in 4. For walls, the minimum is 100mm.
- The spacing between supports on either side of an end lap in rood sheeting is to be as recommended for end spans.
- For pierce fastened roof, the end lap is to be positioned over a support and the fastener frequency to be as for an end support.
- Concealed-fastened sheeting is not to be lapped. Use the stepped expansion detail in Clause 7.7, with the overlap positioned just clear, and on the high side of the support. This will allow normal concealed fastening at the support.
- As concealed-fastened sheeting requires pierce fasteners through the trays to secure an end lap; on steel supports the lap could alternatively be positioned over the support with valley fasteners borth securing the lap and fastening the sheeting. In this case, the sheets would be anchored at the lap and thermal movement would be towards the ends of the sheet as it would be for a single sheet length.Condensation forming on the underside of the roof can cause corrosion at the point where it reaches the cut edge of the underlapping sheet. OVer time, this can perforate the top sheet as the coating is consumed by reason of it trying to sacrificially protect the cut edge. Roofs with relatively low pitches are more prone to this corrosion.
- A continuous strip of plastic, such as polythene damp course inserted into the lap so that it projects from the top of the lap by 50mm, will deflect the condensation from the cut edge.
Alternatively, a generous bead of neutral-cure silicone rubber sealant extruded on the top edge of the bottom sheet prior to being overlapped will both seal the edge and deflect the condensate.
SA HB39 2015 Extract
c) Maximum length Eaves gutters to not exceed 20 m without provision of an appropriate expansion joint, and eaves gutters to be installed to permit expansion and contraction so as to protect cast-type bolted clamp angles where installed.
4.4.3 Corrosion due to crevices
Metal roof drainage systems and support systems shall be designed and installed to achieve complete drainage or drying. Shielded areas capable of causing permanent ponding shall be avoided to prevent the possibility of intense localised corrosion known as crevice corrosion.
Parramatta Roof Inspection Report Conclusion
Due to the extent of deterioration and widespread non-compliant ingress issues, we believe the most economical long-term solution is to provide a complete replacement of all roof sheeting and associated flashings. The surrounding parapet walls should be provided with sheeted wall cladding and the Eaves gutter requires full replacement with the falls adjusted to eliminate the corrosion and allow total drainage.
The mechanical units will require disconnection and the mechanical lines are to be extended to incorporate a P.V.C gooseneck shroud.