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A RANZ Consumer Guide to Re-Roofing

The process of re-roofing a home is not something most New Zealanders are involved in very often, if at all. Here's some guidance to help you through the process. 

Realistic quotes

There’s nothing wrong with getting several quotes. However, if it is only to get the lowest price, you may be doing yourself a disservice. Useful things to consider include: How did the roofer arrive at the price? What is included? What products have they offered? Will it work in the environment? Will it work on our house? How will they do the work safely? What other extra costs should we consider?

Replacement products & Building Consents

The products you can choose for your roof might be limited or numerous. Most re-roofs are a ‘remove what was there and replace with the latest version’ scenario. This should not require a Building Consent as this is considered exempt under Schedule 1 of the Building Act. However, if you are making a significant change of roofing product from the existing type to another, then your roofer must clearly step you through what is required. For example, replacing a metal roof with a heavyweight roof would require a Building Consent and structural changes. Structural alterations to accommodate another type of roof may need new Consent. It is important to check with your local council if a Consent is required. Failing to get a Consent when one is needed could impact your insurance.

Minimum pitch requirements

All roofing products have a minimum pitch at which they will perform. If you have a low-pitch roof (less than 3°), we recommend lifting the pitch to 3° or more. Failing to do that will have warranty implications (usually no warranty), and the work will be non-compliant. Tile and shingle products also have minimum pitch requirements-check with the supplier. Even though a Building Consent may not be required, building work (including re-roofing) must comply with the Building Code and the Building Act. Re-roofing is included in the definition of Building Work.

Not all products are equal

Some roofing products are available in different grades depending on the environment/climate where they will be used. If you are in a coastal or geothermal area, make sure the product offered will work in that environment. Find out what brand of product is being offered and do some research. A reputable supplier will provide advice on this. Some suppliers will check your location and advise if the product will work on your home. The product offered in the quote must be the one used. Product substitution can be problematic.

Gutter capacity

If the roof has internal gutters, check gutter capacity with a current catchment calculator so that allowance has been made to cope with higher rainfall events. Just because it worked in the past does not mean it will manage going forward. An excellent calculator is in the NZ Metal Roofing Manufacturers Code of Practice V3.

Replace everything

A re-roof is a compilation of elements that complement each other to provide a structural, weathertight, compliant solution. For most roofing types, numerous details have similar names but are of a particular type depending on the roof type used. The best outcome is to replace every component.


Ridge flashings, barge flashings, head flashings, apron flashings, valley flashings, parapet caps and underlay are some of the terms that should be there if those elements exist on your roof. These can also be referred to as trims and cappings. The names of details can also be particular to the roofing type. Some of these terms apply to membrane roofs, but the most important part of a membrane re-roof is the substrate (what the new membrane will be attached to). However, consideration needs to be given to keep the ‘hard to replace’ elements in place, which may be embedded behind other building products, such as stucco wall cladding. A competent roofer will step you through the various aspects and limitations.

What’s included?

Ensure you understand what is in and, more importantly, what is out of scope and why. These are usually written on your quote as ‘tags’, options or allowances. Tags may include allowances for timber repairs and/or how items attached to your roof will be managed, such as satellite dishes, solar panels, skylights and wall cladding intersections. The quote may also mention what is or isn’t included, such as whether the spouting is being replaced. Roof insulation would be another example. Be clear with your roofer about what implications this may cause (or not).

Be realistic

Some areas around tags do cause some disagreements. Older roofs will have moved structurally, and can result in visible alignment issues. How straight do you expect the roof to be? Has your roofer checked for humps or sags in your roof? Be clear with your roofer about this. Also, be mindful that, given the age of your roof structure, it could be challenging to get the roof perfectly straight. Some compromise may be required. For flat roofs, ponding should be addressed. This can be more difficult to achieve depending on the substrate. Timber repairs are another potential disagreement area if not understood. The extent of timber deterioration is typically not fully apparent until the old roofing is removed. Some leeway may be required. It is unrealistic to expect the roofer to allow for this in the quote.

New insulation?

When doing a re-roof, consider doing other work that will be easier to achieve with the roof off. New insulation is a very smart, economical and sustainable thing to do, for example. The majority of heat loss in a home is through the roof space.

Ensure you’re insured

Insurance is an essential part of your re-roof process but is often misunderstood as to how it works. As the homeowner, you need to contact your insurer and let them know that you are having the home re-roofed. Your insurer should advise what, if anything, you need to consider. The roofer should also have insurance. Check. In the unlikely event of something happening that activates an insurance claim, you need to advise your insurer. You would claim on your policy. If your insurer considers it the roofer’s fault, they will pursue the roofer and their insurer to recover the loss.

Safety & access

The roofer will allow for various safety considerations. The most obvious are scaffold/edge protection systems, which are very common. Harnesses are another safety method used. Your roofer needs access close to your home. However, they also need to be considerate that you will be living on-site. Animals need to be secured. Parking for you and the roofer is another consideration. Usually, there will be a need for large delivery vehicles. Will your driveway sustain the load? These delivery vehicles can be trucks with cranes attached. Overhanging trees can also be a problem. Insurance policies require a 4-square-metre gap around your driveway so a fire appliance can reach the property. That space should also be suitable for most delivery vehicles.

If younger people are on your property, do not let them climb or play on the scaffold/edge protection system. It would be best for them to stay inside while the re-roofing is done. Likewise, the roofer will watch out for all people on a site, so please give them space and follow their safety instructions. You may be tempted to climb onto the scaffold/edge protection system and see how the work is progressing. Before you do that, contact the roofer for their express permission–and it is best done with them present, anyway.

Site space

Site housekeeping is essential, too. The roofer usually requires a workspace to store and work with the roofing product as it is installed. Also, the roofer must secure materials at the end of the day and ensure there is no debris spread around the site, which could cause a cut or trip hazard, for example. Your roofer will also require power and, if possible, a toilet.

Weather allowances

The weather has a significant impact on re-roofing. Rain is not the only consideration. Wind conditions can also cause unsafe situations. The effect of the weather is for the roofer to manage as they are best placed to make that decision. The day may start fine and still, but weather can change quickly, and the roofer will need time to make your roof weathertight before the incoming weather arrives. It may be prudent for the roofer to be elsewhere on such days.

Discuss timelines

Be assured the roofer wants to complete your roof as soon as possible. When choosing your roofer, get approximate start dates and how long the work should take. These dates can’t be set in stone for many reasons, so please bear this in mind. There are many moving parts for the roofer to manage, some of which the roofer may not have direct control over. For example, an outside business may be supplying the scaffolding/edge protection.

Also, very few roofing products can simply be picked up off the shelf. Most are made to order or need to be ordered well in advance due to lead times or may require specialised transport. And not all elements come from one source. Other trades may need to be coordinated and their availability confirmed, such as a plumber, gasfitter, builder, solar installer or satellite dish technician. Trades don’t always line up, which can cause delays. The expectation is that your roofer will communicate all the above with you.

Signed contract

Always get a contract with your roofer. This should set out what is involved, what product will be used, the colour choice and grade of the product, and the terms of sale. It is not unusual for the roofer to ask for a deposit – 50% is not uncommon. The contract should also set payment terms. The roofer may use the Construction Contracts Act (recommended). They must give you Form 1 if they use the CCA, which clearly sets out how both parties shall deal with payment. Do not pay cash for anything.

Unforeseen problems

If problems occur during your re-roof, you should expect your roofer to provide timely communications with professional responses. Your roofer must provide weathertight, compliant work that meets or exceeds recognised industry documents and manufacturers’ requirements. Both parties should be polite with their enquiries of each other in this space. RANZ members are expected to own problems of their doing and reasonably make good such problems.

Get warranties

Typically, warranties come in two parts: workmanship and materials. Workmanship warranties cover the work the roofer/installer has done. Material warranties come from the roofing supplier/manufacturer and are particular to the components. Keep invoices and warranties as proof of purchase. To maintain warranties, there are usually maintenance requirements which you, as the homeowner, must carry out. Ask your roofer what needs to be done to maintain the warranty requirements. Please be very careful and sure of your safety if you decide to carry out maintenance work yourself.

As you can see, there is plenty to get your head around regarding re-roofing. Always use a member of the Roofing Association of NZ. Always ask questions and ask for referrals of previous work done by the roofer. Ultimately, you need to be comfortable with your choice of roofer. If you’re not sure, get someone else.