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Raise The Roof

Amy Hamilton Chadwick finds out why roof maintenance should be high on your priority list.

By: Amy Hamilton Chadwick

1 August 2016

The roof of your property is like the hair on the back of your head: you don’t look at it very often and you tend to assume it’s doing its job, looking good and keeping you warm.

Any news to the contrary often comes as a nasty surprise. But luckily, you can easily repair or replace any bald patches in your roof, and with the right maintenance it will last a lifetime.

Most types of roofing should be cleaned every three years, whether with a light chemical treatment or a low-pressure water-blasting, says Christine Black at Kowhai Roof Coating’s head office. Metal and concrete tile roofs will need recoating around every 12 years.

Maintaining Your Roof

Follow those directions and you should never need to replace your roof, Black says. But ignore your roof and you’ll start to see problems arise between years 10 and 15. If you then restore your roof it might cost you around $7,000, but continue to ignore it and the cost of reroofing will be at least $30,000.

The main problem areas for various roof types, Black says, are:

  • Disintegrating concrete tiles – left unsealed these will break down to something like sand. They need to be cleaned, sealed and coated.
  • Metal roof tiles – the top coat will erode over time due to moss and lichen, which can eventually lead to rusted tiles with holes.
  • Pointing – the weathertight seal where your roof ridge is bonded to the rest of the roof. If that breaks away it can lead to leaks; this can be hard to spot.

Guttering is another leading cause of preventable roofing problems. Overflowing gutters, especially in a valley-style roof, or combined with an undersized drainpipe, can quickly lead to leaks. Gutters can sag, crack and degrade, but are relatively cheap to repair. When it rains, look for water running directly down from the gutters; full gutters and downpipes can block your drains, allow water into your walls and rot your boards.

Doing Roof Repairs Yourself

A lot of roofing work is restricted and must be completed by a licensed building practitioner who is specifically licensed in roofing work. You may be able to undertake minor repairs to your roof, like replacing tiles or reattaching guttering, but you need to know what you are doing and have appropriate safety equipment.

Falls from roofs and ladders account for 70% of falls in construction, according to Worksafe.

Far better than doing it yourself is hiring an expert and roofing repairs are relatively inexpensive. The average cost of a roofing job posted on BuildersCrack.co.nz is $660 and each month around 250 roofing jobs, mainly repairs, are posted, says co-founder Jeremy Wyn-Harris.

If you've got a good roof now, look after it! - Christine Black

He says you can spot a pattern of more roofing repairs being required in coastal areas, particularly in Wellington, as well as in Invercargill which posts more than double the average proportion of roofing jobs. It’s a reminder that the more your roof is exposed to the elements, the more care and attention it will require.

A good relationship with a roofing company is a must, says investor and property trader Rachel Ward. Before she buys a property she always ensures the roof is in good condition, though she has had to reroof a few properties over the years. She chooses long run metal roofing for its low-cost, low-maintenance qualities. This is the most popular material in New Zealand, but if you are re-roofing, there is a wide range of options to consider.


Long run (or long line) metal roofing is made from steel, coated with a zinc-aluminium alloy. Suitable for virtually any type of roof, comes in a wide range of colour choices and can be easily repainted; it’s also lightweight and simple to install. Metal roofing is generally the most affordable choice, starting from around $60 per square metre with low installation costs.

Metal Tiles(AKA Decramastic Tiles)

These are made in a similar way to long run roofing, from alloy-coated pressed steel, and come in an equally wide range of colours. There are also a number of texture and shape options for a high degree of customisation. Metal tiles start from around $55 per square metre, though it takes longer to install than a long run metal roof.

Concrete Or Clay Tiles

Supremely durable, concrete or clay tiles keep their colour and wear well in almost any location. They also provide a breathable thermal mass on the roof that boosts heat retention in the house, as well as absorbing noise to give a quieter environment. But they do weigh more, so expect to spend more on trusses and installation than for a long run metal roof. You’ll also need to check regularly for moss or lichen growth. Concrete tiles start at around $60 per square metre; clay from $120 per square metre.


When you have a flat or curving roof, a membrane roofing system is the best choice to ensure complete weather-tightness. It’s a lightweight option and easy to repair, with prices starting from around $100 per metre.

Asphalt Shingles

An increasingly popular roofing choice in New Zealand, asphalt shingles are made by applying modified asphalt to a fibreglass mat base. They come in a range of colours and are around $65 per square meter. Quality brands carry a long-life warranty and an algae-resistant coating can be applied before installation. Asphalt shingles are lowmaintenance and attractive, though only suitable for a sloping roof.

Big Budget Options

Several other fantastic high-performance materials are available, but none are really cost-effective for a rental property. Timber shingles start at around $160 per square meter and look really attractive. They provide great insulation, are sustainable, long-lasting and can be painted or stained.

Slate tiles look gorgeous, weigh a ton and will last for literally hundreds of years if well cared for; prices start from about $300 per square metre. Copper tiles start at around $250 per square metres and are beautiful, malleable and resistant to all kinds of corrosion. Copper is also highly likely to be stolen off your rental, as it can be sold for around $6 per kilogram as scrap – the same reason copper downpipes and hot water cylinders so often go missing.

Roof Red Flags

Here are five warning signs that your roof may need repairing or replacing:

  • Damp patches in the ceiling or exterior walls.
  • Chips in your gutters. When the coating is coming off your roofing material and gathering in the gutters, this is a definite red flag.
  • Light visible from inside the roof space – if light can get in, so can rain, damp air and mould.
  • Your roof is over 25 years old and you’ve never maintained it.
  • The roof is sagging – this is typically a structural problem. Your roof may need bracing (and so will you when you get the invoice).

Information Resources

The first step for any job is to do your research. Here are a few suggestions to get you started:

  • Building.govt.nz provides a list of restricted building work and advice for choosing a building practitioner.
  • The Roofing Association (roofingassn. org.nz) provides a database of specialist roofing contractors and information about the trade. For an estimated price range on your roof repair or replacement, try the BuildersCrack estimator.
  • Failing to look after your roof is certainly a false economy. Include it in your regular rental maintenance costs and it will continue to look good and protect your property for decades to come. “If you’ve got a good roof now, look after it!” Black says. “It will last forever and a day.”

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