Even the best laid plans don’t always work out exactly as intended—sometimes, product substitutions are required. But substituting one weatherboard material for another isn’t a reason to substitute good building practice as well.
Generally, any product substitution in a home construction (weatherboards and cladding included) needs to fulfil the same requirements as whatever is being substituted.
This includes meeting the same building regulations, including consents for major substitutions—of which exterior cladding is one.
Getting the substitution signed off before you start work is particularly important. If you start work before you get the consent, you can’t apply for it retrospectively. Rather than a certificate of compliance, you receive a certificate of acceptance, which is not as valuable, as it can impact the ability of the homeowner to sell in the future.
Getting client approval
The client must also agree to the changes, and must be aware of the difference between the two products. This is especially important if there are significant differences in maintenance schedules.
Your best bet in this regard is to ensure you get everything in writing. A verbal confirmation from the client won’t do if they decide to lodge a dispute later on.
If the substitution is approved by both the Building Consent Authority (BCA) and the client themselves, there’s one last potential hurdle to overcome at the end of the build: ensuring they have the correct maintenance information about the new weatherboards rather than the old weatherboards.
Failing to complete these steps can result in a fine. However, the Ministry of Business, Innovation and Employment have a thorough, in-depth guide to general product substitutions as well. We’d suggest you follow this guide if you are unsure of your obligations.
Below you’ll find some common considerations when substituting one weatherboard material for another, structured by material type.
See how these different weatherboard cladding materials perform against each other.
If switching over from pine to cedar, note that pine does not experience the same level of shrinkage and expansion as cedar—this may affect the spacing requirements of your weatherboards in particular. The product information of the cedar substitution will have more information.
If you are substituting to pine, or any other timber for that matter, ensure you have suitable storage for the cladding during the install—especially if the timber has not been pre-treated for weatherproofing. Weather damage can hamper installation efforts and cladding durability.
If you are substituting to cedar, ensure that the stakeholder understands that cedar will age or silver without proper maintenance. While it is weatherproof without staining or painting (unlike pine), it is still susceptible to environmental erosion and requires careful maintenance.
If you are substituting to fibre-cement weatherboards, it’s important to note that they are prone to thermal movement i.e. the material can expand and contract in response to temperature fluctuations, changing its dimensions.
To accommodate this special vertical joints need be incorporated in between the horizontal weatherboards during installation.
In addition to this, fibre-cement weatherboards are generally a proprietary system that rely on a series of compatible components to be correctly installed. For this reason it is recommended that installers adhere to the specific manufacturer's instructions to avoid any issues.
Aluminium cladding can create dew-point formations within the cladding itself, and without a breathable cavity (such as that provided by a bevel-back profile), this can result in moisture problems.
Aluminium cladding may take longer to install.
uPVC weatherboard cladding is typically a complete proprietary system, including all finishing accessory options, that relies on the correct installation of a series of interlocking ‘clip-together’ components. It is recommended that installers adhere to the specific manufacturer's instructions to avoid any issues, but they are relatively straightforward and quick to install.
uPVC weatherboards generally require an absorbent wall underlay. If swapping to uPVC from timber (which can use either an absorbent or non-absorbent underlay due to the material’s natural absorbency), ensure that this underlay is in place.
If moving away from uPVC, ensure the difference in installation times are communicated as well. uPVC weatherboards are generally quicker to install, thanks to their proprietary clip-in system and often comes as doubleboard profiles.
There are also significant maintenance advantages to be gained by switching from timber, for example, to uPVC weatherboard cladding. This is because uPVC does not require any painting during its lifetime as the weatherboards are manufactured pre-finished.
For more information about different weatherboard materials—and which is right for your latest project—investigate our new guide available below.