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The estimating process

Some of the variables and tricks when it comes to estimating costs and comparing estimates.

Getting an estimate

An estimate needs to be done onsite by a qualified roofing installer. They need to be able to assess the state of your current roof, measure for a new roof, and look at access to both your property and the roof to be able to provide an accurate estimate.

Finding a great installer

Selecting a great roofing installer is a key part of the process; an experienced, professional installer will make the process significantly easier for you and give you better value for money. Don’t just look at the price, as there are some other things to check and consider.

  • Check they’re a Licensed Building Practitioner
  • Check they’re a member of the Roofing Association of New Zealand – all their members are listed on their website (
  • Ask to see some examples of work they’ve done in the past
  • Ask to see references from previous customers

We have a number of tried and tested installers in each region that we are happy to put you in touch with. To find an installer in your region see our installers page.

What impacts an estimate

There are lots of variables that can go into a detailed roof estimate and every roof is unique – that’s why you’ll need to get an expert to come onsite to get it right. However, we’ve listed common things that affect the final estimate.

Existing damage to the roof

If your roof has already started leaking into the roof space, it could increase the costs to replace it, with insulation or internal structures potentially needing to be replaced.

Size of the roof

Larger roofs are generally more expensive; however, the cost per square metre can reduce with a larger roof.

Product choice

The profile, finish and colour you choose can affect the cost, because some choices are more expensive than others.

Design complexity

As a rule, the more corners your roof has, the greater the cost. Chimneys, skylights, narrow hips, and raking cuts will increase roofing costs.

Location & Site access

Freight costs and proximity to your nearest installer can affect the cost, and unusual or difficult to access sites may require special equipment.

Roof pitch & rafter spaces

Roofs with a higher pitch or larger rafter spaces generally cost more. With two-storey homes, the cladding and pitch govern the type of flashings required for the top storey.

Changing roof type

If you are changing between different roof types, this can require new structures like battens or purlins to be installed.

Comparing estimates

When you have a couple of estimates completed, you may find that they vary significantly in cost. It can be tricky to understand why, so we’ve put together a handy little checklist of important pieces of information that should be on your estimate, which can help you compare between them:

  • Have they listed the profile (shape of the roof), material, and colour you’ve requested?
  • What substrate and grade of material are they recommending if you’re having a longrun roof?
  • Is the estimate for the supply and installation of the new roof?
  • Does the estimate include gutters, downpipes, and flashings (for all penetrations such as chimneys, skylights, or vent pipes)?
  • Does the estimate include all rivets/nails/screws for the job?
  • Does the estimate include roof underlay at the right quality?
  • Is insulation included in the estimate?
  • Does the estimate include the addition of battens or purlins if you’re changing your roof type?
  • Does the estimate include the removal and disposal of your current roof?
  • If you need council consent, is this included in your estimate, or do you have to arrange this yourself?
  • Is the warranty both for material and installation/workmanship?
  • Does your estimate include edge protection or scaffolding (a legal requirement by WorkSafe)?
  • Do you need to engage a builder to remove any weatherboards so flashings can be replaced?
  • What is excluded from the estimate?
  • Have they discussed with you the compatibility of proposed materials e.g. water runoff from copper on to Zincalume is to be avoided?
  • Are they a Licensed Building Practitioner (LBP) and can legally sign off on the work?
  • Do they have insurance to cover their work?
  • Does the quote include GST?
Things to consider

Allow a bit extra for any unseen or hidden problems to the structure of your roof. Until a roof is removed, it is impossible to tell if you’ll need any repair work to the structure – particularly if your roof is quite damaged.

Finally, if you’re not sure of anything, ask. You want to make sure you fully understand what you’re getting and most roofing installers will be happy to help!


Generally, you will need to pay a deposit upfront by cheque or bank transfer and the rest of the payment is due once the roof has been finished.

Arranging Finance

As replacing your roof can be an expensive job, it pays to get your paperwork sorted before you start. The good news is banks generally view re-roofing as a good investment to protect the value of your home, so conversations about extending the mortgage should go smoothly.

Check out what your bank has to say. You can click on the links below:

ANZ - Your finance options

ASB - Top-up your ASB home loan and bring your dreams to life

BNZ - We can help you find the best way to pay for your renovations

KIWIBANK - Borrowing to renovate

WESTPAC - Financing for building

The next step

If you would like to request an estimate we have a number of installers in each region listed on our installer page.

Once you’ve assessed and decided on the best estimate for you, you’re ready to get your new roof. Check out the next step to see what will happen in the installation process.

The look book 04

The Look Book

The Look Book is full of inspiration for home exteriors, and outdoor areas, covering a wide range of building designs. From classic to modern masterpieces, it's brimming with ways to make your dream home come to life. So download a copy, and be inspired!