New Zealand Roof Types

New Zealand has a largely varied climate and our roofs need to be able to withstand strong winds, heavy rain, snow, hail, coastal conditions, and intense sunlight. It is important that all of roofs are designed and installed correctly by a qualified roofing professional. The majority of roof claddings are required to be installed over an underlay which acts a second line on defence in case water penetrates through the roof cladding. The main three types of roof in New Zealand are; heavy weight tile, light weight tile, and profiled metal.

Heavy weight tile roofs will either be composed of clay or concrete and tend to be installed on a roof with a reasonably steep pitch. They weigh a significant amount more than metal roofs so will require to be installed over trusses that can bear the load. If maintained well, heavy weight tiles will have a long lifespan. They are reasonably low maintenance because they do not require painting, cannot rust, are fire resistant, and will not be affected by insects or rot. When maintenance is required, access can be difficult because heavy weight tiles are brittle and have a tendency to crack if they are walked on. During an earthquake, heavy weight tiles do not tend to perform well and can cause significant damage to a property. A consent is required if a light weight roof is being changed to heavy weight to ensure the bracing, trusses and lintels can support the extra load and reinforcing required.

Heavy roof tiles after seismic event

Light weight tiles are made of metal and tend to be less expensive than heavy weight but generally will not last as long. The finish can be either be stone-chip or a painted/coloursteel look. In the 70s and 80s Decrabond or stone-chip finishes on light weight tiles often had an asbestos content and we recommend all Decrabond roofs from this time are tested for asbestos. The tiles can dent if they are walked along but generally do not crack, although they do get brittle as they get older. If a roof is being changed from a heavy weight tile to light weight it will not require a consent as the trusses will already be strong enough to support the load.

Asbestos in light weight tile roof

The third most common type of roof is profiled metal, which is generally, corrugated, trapezoidal, or tray. It used to be common practice for profiled metal roofs to be fixed with lead head nails which, over time have a tendency to rust from the inside out. If we identify lead head nails on an inspection will always recommend they are replaced within twelve months. This is because when they rust it allows the opportunity for water to penetrate through the roof. Profiled metals used to be sheeted which can allow rust to form in the overlap of each sheet, now they tend to be long-run which eliminates the problem.

rusting lead head nails

Almost all types of roof claddings can be prone to lichen and an important part of roof maintenance is reducing lichen growth. There are a number of products that a home handyman can use to spray their own roof lichen, in some scenarios it is recommended a professional is contracted. If a property is rural, downpipes must be disconnected when spraying lichen so that chemicals do not contaminate the potable water supply.

If you require an inspection of your roof, call us today -0800 487 884! 

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