Custom Orb Metal Roofing (generally and as applicable to this residence)
Galvanised iron and zincalume custom orb (corrugated) sheeting is commonly used as roof cover on pitched roofs whereas galvanised or zincalume metal tray type sheets/sections are commonly used on roofs where there is little or no fall. Zincalume custom orb and flat tray sheeting can be factory coated and this is called “Colorbond”. Galvanised iron custom orb sheeting is still available today and it dominated Queensland housing from 1880 until the late 1940s when tiles became more popular. Many houses especially with high pitched roofs and built as far back as the 1920s, still have the original roof sheeting in place however after a service life of around 60 years, this sheeting is prone to corrosion especially where sheets are overlapped and around the old lead head nails. Lack of paint cover can also be a factor. Rainwater entering into roof battens around nail shafts and through corroding sections, can cause damage and it is not uncommon when “re-roofing” to find that many roof battens and other timbers require replacement due to moisture decay. The Consultant is not a roof specialist and any opinion given can only be based on building experience and house inspections over a number of years and may not be entirely accurate. While maintenance such as the placement of new roofing sleeves under existing corroded overlapped sheets, replacement of lead head nails with roof screws, and applications of specially formulated Ormonoid paints manufactured by Davco such as brushable water proofer or bitumen paint followed by 2 coats of “Silvershield”, may prolong service life, it should be compared to the benefits and costs of replacing the roof. Inevitably, any metal roof, including original gutters and downpipes from 25- 60 years of age or more, as well as some roof battens and perhaps other timbers compromised by decay, will have to be replaced. While ongoing maintenance such as partial replacements can prolong the service life of gutters and downpipes it is also more economical to replace all gutters and downpipes at the same time. For more specialised advice on the condition of this roof including maintenance and/or replacement costs, please refer to licensed roofer of choice.

