Skennars Head Roof Inspection 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 and Manufacturer’s Instructions. Provide recommendations to extend longevity.
Inspection Site Gallery
Findings & Recommendations Report For Skennars Head Roof Inspection
- Sprung curved roof is non-compliant to the Manufacturer’s Instructions. Straight sheeting has been laid on a sprung curved roof with an excessive radius at the apex. This has resulted in the sheet laps becoming exposed due to a noncompliant radius and have previously suffered ingress.
- Silicone has been applied to the laps however, given that the sheeting exceeds the radius limits, the sheet laps are exposed to excessive forces, excessive support spans and will result in repetitive failures and ingress at the sheet laps.
- Support spans of the sprung curved roof are excessive and non-compliant to Manufacturer’s Instructions. Support spans of approx. 1500mm shown.
- As displayed in the tables included in the report, maximum 900mm spacing with a 0.75mm batten is required.
- The curvature of the apex can be determined by scaling the architectural drawings attached or
measurement. The radius of curvature of the apex is 6m. Table 4.2.1 of the Lysaght Manual specifies the minimum radius for spring curved roof. The radius is less than 8m so therefore the roof is not installed as per manufacturer’s instructions. - Post penetration is located on a sheet lap, compromising the anti-capillary feature and is at risk of ingress. Non-compliant to AS 1562.1 refer Appendix D.
- Apron flashing is non-compliant to SA HB39 refer 8.2. Flashings have not been tightly notched and have not been fastened at the required intervals. Rear of the apron flashing shown not lapped in the direction of flow.
- Tray / Soaker flashings are heavily reliant on silicone and have not effectively been provided 150mm of coverage for a transverse apron. Non-compliant to SA HB39 refer table 8.1.2
- Solar hot water system is corroded and the runoff has heavily influenced the corrosion of the eaves gutter.
- Apron flashing has not provided 150mm of effective coverage. Non-compliant to SA HB39 refer table 8.1.4.
- Eaves gutter shown is suffering heavy ponding, resulting in corrosion. Non-compliant to AS 500.3 refer 4.5.3 and 4.4.3. Eaves gutter has not been provided an effective gradient to the downpipe outlet
- Original roof fasteners of Class 4 had deteriorated and were replaced. The fasteners below the Solar panels and the hot water system were never replaced and corrosion / corrosive run off persists.
Building & Installation Code References found in Skennars Head roof inspection report:
5.8 JOINTING METHODS FOR OTHER THAN ALUMINIUM
5.8.1 General
Soldered or silicone-scaled joints are to be flush and lapped 25 mm in the direction of the
fall , with one row of rivets or other approved type fastenings at spacings not exceeding
40 mm. This applies to all joints in flashings, cappings, caves, gutters, box gutters, soakers,
penetrations and all general sheet metal joints in roof plumbing.
8.2 FASTENING
Roof flashings and cappings are to be fastened as given in Table 8.2(A) and the following:
(a) Roof flashings and cappings to be fastened to withstand wind pressures and thermal
Movements.
(b) Roof flashings and cappings to be tightly notched and fastened at the intervals given
in Table 8.2(8).
(c) Intersections, laps and mitres are to be fastened and sealed as per Clause 5.8.
(d) Joints in flashings and cappings other than straight joints to be accurately mitred,
fastened and sealed.
(e) Joints in flashings and cappings to be 25 mm and fastened at intervals not exceeding
40 mm. Joints are to lap in the direction of fall.
(t) All joints are to be watertight on completion of the installations.
4.5.3 Eaves Gutters
Eaves gutters shall be installed as follows:
(a) Gradients Deviations from nominal gradients shall be smooth and not cause
permanent ponding.
NOTES:
Where a building is likely to move due to reactive soils, gradients may need to be not
flatter than-
a) 1 :250 to achieve an effective gradient not flatter than 1 :500; or
b) 1 :500 to achieve an effective gradient with no permanent ponding.
Light condensation will not generally cause permanent ponding, whereas heavy
condensation, particularly in conjunction with retained si lt, can reduce the design lifetime
of the product.
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.
Manufacturers Instructions References In Roof Inspection Report
Spring Curving
Stramit Curved Corrugated cladding can be spring curved, concave and convex, including curved ridges, provided it is sealed at the apex, and within the recommended limits
The anti-capillary feature shall meet the following requirements:
(i) The anti-capillary feature shall be positioned on the overlap lip side of the roofing
side lap.
(ii) The anti-capillary feature shall be between the mating surfaces of the lapping ribs.
(iii) The anti-capillary feature shall provide a minimum separation of 1 mm.
(iv) The anti-capillary feature shall not be compromised by installation practices such as
over-tightening of crest fasteners .
If any one parameter (i) to (iv) above is not met, the profile shall be deemed as not having
an anti-capillary feature.
Conclusions Found In Skennars Head Roof Inspection Report
- The Sprung curved roof is largely non-compliant due to flat sheeting being laid on an excessive radius, with excessive support spans.
- The sprung curved roof must be removed and replaced and additional support spans must be provided to ensure the sheeting is installed as per Manufacturer’s Instructions.
- Tray flashing required to the post penetration to eliminate ingress risk due to compromised anti-capillary.
- Apron flashings that are identified should be replaced to provide compliant coverages. The Solar Hot water system must be replaced to eliminate further corrosion of the sheeting and eaves gutter.
- Rear apron flashing must be replaced to allow for compliant coverage. Cladding removal required.
- Eaves gutter must be replaced and the fall towards the downpipe must be remedied to eliminate ponding and future corrosion. All roof screws that were not previously replaced, should be replaced to ensure no future corrosion of the roof sheeting and drainage components.