Maintaining your roof in Australia


The roof exterior can be tricky to closely inspect without getting onto the roof. Accessing the roof is a potential safety hazard and I would not recommend it unless you are a professional with the right gear and insurance. Many roof defects can be detected from the interior and from the ground. I suggest you inspect the roof from the ground only and leave the full roof inspection up to the building inspector or Roofer.

 Metal sheet roof

If possible, get to some high ground from where you can view the roof. If the roof is a metal sheet type of roof, the biggest concern will generally be rust. If there are areas of rust, the rust can cause holes in the roof that allow water penetration. Sometimes the rust is visible from the ground as brown patches. Often the most significant rust occurs where roof sheets overlap, and this is not easy to see from the exterior. If the roof is the original roof, and access is difficult from the ground, then ask the building inspector to check it from inside the roof.

Generally, a metal roof will last for about 50 years, so if the building you are looking at is more than 50 years old, the roof should not be the original roof. If it is the original, it may need to be replaced. The average cost of replacing a roof on a single-storey house of around 100m2 is $15,000 or more.


Hail damaged roof

I once inspected two new blocks of townhouses and found both blocks had hail-damaged roofs. The real estate agent and builder had not disclosed their knowledge of this matter to the purchasers. The cost to replace an entire roof would have to be claimed on the body corporate insurance as the buildings were complete. To rectify this defect, scaffolding would need to be erected around the entire building, the old roof would need to be removed and a new roof installed. The body corporate would need to fund the excess on the insurance claim and each owner may also have to pay an increased premium each year as a result of the body corporate making such a huge claim.


Metal roof tiles

Metal roof tiles are tiles that look like concrete tiles from a distance, but upon closer inspection you can see that they are metal. These were popular in the 1980s. Metal tiles are flimsy and if you don’t step very lightly in soft-soled shoes right above the tile batten they will dent.

 Most of the clients I inspect for have no idea that the house they are buying has a metal tile roof. The single-storey, tenanted houses always have the worst damage because tenants do not seem to notice the damage they are causing when they get on the roof, for example to retrieve a lost cricket ball or adjust the TV antenna.

 Concrete tile

Concrete tile roofs have capping tiles at the ridges, hips and gables that are wired onto the frame, secured and waterproofed with mortar. This is known as ‘bedding’ and ‘pointing’. Over time, bedding and pointing can become cracked and loose, and this allows water penetration. The cost to repoint an average sized tile roof of a house is $2,200 or more.


 Terracotta tile

Terracotta tile roofs are the orange-coloured tile roofs. These roofs are long-lasting and attractive, but they are more prone to leakage in heavy rainfall as the gaps under the tiles can allow wind-driven rain to enter the interior and cause minor damage to the ceiling. The lichen that grows on terracotta tile roofs is generally harmless and can be removed with pressure cleaning if a cleaner appearance is desired. Tiled roofs will have a life expectancy of approximately 60 to 100 years plus. Terracotta tiles last longer than concrete tiles. Terracotta tiles can be prone to pitting. This problem is known as ‘fretting’ and it manifests itself by leaving small piles of tiny flakes and grains of terracotta on top of the ceiling inside the roof void.. Over time, the fretting can become so severe that some of the affected tiles need to be replaced.



As well as checking the roofs, you need to inspect the elements around them, such as fascias, eaves, gutters and downpipes.

Fascias are the timber boards that support the gutters. Check these boards for evidence of fungal decay (rot). They will often have some minor decay at the corners where gutters overflow. Minor decay only needs patching and repainting, but more significant decay may require replacement of the entire fascia. Gutters will need to be removed and replaced if the fascia needs replacing. The cost of this work will increase significantly if scaffolding needs to be erected to access the fascias.

Eaves (or ‘soffit’ as it is also known) are the lining boards or sheets used under the roof overhang. A roof overhang is a good thing because it protects the building from the elements like heavy rainfall and hot summer sunlight. When there is no overhang of the eaves, and the gutter sits on top of the external wall, the risk of leaks is much greater. Check the condition of the eaves. If eaves are broken or have peeling paint, and the eaves’ lining material contains asbestos sheeting, then the cost to rectify this is significantly increased.

Inspect the gutters and downpipes from ground level for any signs of rusting or leaks. Leaks often occur at joins. Rust can be caused when trees overhang the roof and leaves are not regularly removed.


What spacing do you require on downpipes?

There should be a downpipe every 12 metres of guttering and a downpipe should be located within 1.2 metres of a valley gutter.

Why I hate box gutters

Box gutters are internal gutters that are often not visible from the ground. This type of gutter is very prone to overflowing during exceptionally heavy rainfall. The water overflows into the building interior and causes damage to other components of the property.

Downpipe connections

 Check that downpipes are connected to stormwater pipes in the ground. If the downpipes discharge water onto the ground this can create excessive dampness that can contribute to timber pest and mould issues.

If the house is an older property, the stormwater pipes could be made of terracotta clay. You can usually see the clay pipe top where the downpipe meets the clay pipe at ground level. Clay pipes are prone to pulling apart and can easily be invaded by tree roots. The cost to replace clay pipes with plastic stormwater pipes is usually a few thousand dollars for an average home.

Why does valley metal rust on a terracotta tiled roof?

If the roof is a pitched terracotta tiled roof that has valley gutters, then check them for rust (from the ground). If they are brown in colour it is likely they have significant rust. It is said that the glaze in the terracotta leaches into the galvanised steel valley metal and causes premature rust, therefore, if the valleys look brown they may be rusting and need replacement.


What if my property has solar panels on the roof?

Many energy-conscious property owners and builders have installed solar panels. These are usually placed on the roof and orientated for maximum sunshine collection. The inverter is a box on the wall, usually located near the meter box. The system converts solar energy to electricity for use at the property. Excess electricity generated can be returned to the grid for a credit on the electricity bill.

Some solar credits are not transferable to the next owner. Solar panel installers have a habit of not properly sealing around the roof penetrations (where solar panels are connected to brackets attached to the roof frame through holes in the roof). This can result in roof leaks. So check the ceiling below the solar panels for leak stains or damage.

Note: Inspection of the solar panel installation is excluded from a standard building inspection report so if you have a property with them installed it best to get them checked by a specialist.

Watch out for a future blog on Solar Panels where we will deep dive into this topic.