Your choice of exterior cladding materials is one of the most significant decisions in determining what your new home looks like. But there’s much more to wall claddings than appearance alone.
In this article, we will explain some of the important factors to consider when deciding what materials are most suitable for your new home. We will then run through the below examples of the different cladding types used on homes in Christchurch and around New Zealand, and take a look at how they measure up to the performance factors that are most important to you.
It might seem obvious, but before any decorative function, the cladding on a building is there to act like the skin of the building – it is designed to keep water out and protect the structure of the building from damage due to moisture ingress.
This protection is often described as the 4 Ds of external walls:
Deflection is the first line of defence, and a wall cladding will be designed to shed water effectively to prevent it getting into the building.
Drainage and drying are accommodated through the use of a cavity between the cladding and the building wrap. This is a gap that allows any water that gets past the first line of defence to either drain out the bottom of the cavity, or dry as a result of air movement. Cavities have always been used for brick veneer cladding in the past, but it was only in the early 2000s that they became common behind other cladding materials as a response to the leaky home issues. Nowadays virtually every wall cladding material is installed over a cavity, though there are some exceptions.
And last but not least, durability is also important so that the cladding performs as required over the lifetime of the building.
When choosing your wall cladding it’s usually best to start out by thinking about the appearance of your new home – are you after a particular colour scheme, or are there any materials that you really like or dislike? This can really help narrow down your options, see the top 10 factors to think about when choosing exterior wall cladding below to help you narrow it down some more!
The below descriptions of different cladding types are listed generally from most cost-effective through to more premium products, though there can be quite a lot of variation within each category. So what options are available?
Think Colorsteel, corrugated iron, whatever you like to call it. In addition to the corrugated profile that everyone is familiar with, there are also trapezoidal profiles available that give a modern angular finish with strong shadow lines.
The main reason that it is such a cost-effective cladding is because it is cheap to buy and quick to install, so it keeps both the material and labour costs to a minimum. In addition to this, if it is installed running vertically then it effectively creates its own drainage cavity, which in some cases can save on the cost of installing cavity battens.
There are very dark colours available, and durability is quite good as long as you pay attention to exposure zones. Each manufacturer will have a higher performance range available that is suitable for use in coastal environments.
In recent years there has been a larger range of different bricks available in New Zealand, which has seen increased use as a cladding material in architectural housing. These bricks offer a totally different look to the mottled beige and red colours you may associate subdivisions full of brick homes – think modern colours such as charcoal, grey or white, and a range of different sizes that can be longer or narrower than traditional bricks, giving a much sleeker look.
One reason for the popularity of brick is its cost-effectiveness – standard bricks can be surprisingly cheap to install, and they have a robustness and permanence that appeals to many people. The cost can increase a bit once you get into different sizes and finishes, but in most cases, brick still ends up being a very economic option once the low ongoing maintenance costs are factored in.
Some people are reluctant to use brick cladding due to the large number of brick houses that failed during the Canterbury earthquakes. Modern brick cladding is well connected to the structure with steel ties, and the bracing structure of the building will be designed to allow for the additional weight of the bricks.
When used on upper levels or above roof level (e.g. chimneys) you can use ‘brick slips’, which are thin pieces cut from the face of real bricks and installed over a backing much like tiles. This has the advantage of being much more lightweight than solid bricks, though it is quite an expensive installation method best used for smaller areas.
Concrete block can also be installed as a cladding and is typically installed over timber with a draining cavity very similar to bricks. If you don’t like the appearance of raw concrete blocks you may be interested to know that they can also be ordered in a range of different colours or with a honed or textured face which can create a more refined look.
Painted weatherboards have been used on houses for generations, and can be a great way of achieving a classic look with strong horizontal or vertical lines.
Traditionally board products have been made of timber, in recent years mostly treated radiata pine. However, there are also a range of fibre cement and plywood products available that can give a range of different modules and patterns.
In every case, the durability of the product is dependent on the integrity of the paint finish which protects the timber or fibre cement substrate from damaging water ingress. For this reason, it is important to ensure that regular maintenance is undertaken before this becomes a problem – ideally, a coat of paint will last about 10 years, but there are some factors that can affect performance:
Plaster is a particularly versatile cladding, as it can be applied over a wide range of substrates. It is most commonly installed over an AAC panel – this stands for ‘autoclaved aerated concrete’ which is essentially a lightweight concrete panel, usually 50mm thick, that is rigid enough to offer good impact resistance without being too heavy.
Other substrates include brick or concrete block, as well as fibre cement sheet where a thinner cladding is required. It’s still possible to use a polystyrene substrate, and while it is cheaper than other options and complies with the same building code requirements most people shy away from it to avoid issues with resale value; many buyers are still hesitant when it comes to polystyrene cladding due to the stigma of leaky home issues.
Similarly to the painted cladding described above plaster does require occasional repainting to maintain the integrity of the paint coating. Some high-end plaster systems include flexible waterproof layers designed to maintain weather tightness even if the paint coating develops minor cracks due to movement. Overall it’s a mid-range option when it comes to price – there are a surprising number of trims, flashings and meshes that get incorporated, and the labour content is quite high due to the number of different base, texture and paint layers that need to be applied by hand.
Plaster is best used for lighter colours, as it can develop cracks if painted in dark colours if the thin plaster layer expands at a different rate to the substrate behind due to heat gain. Some plaster suppliers have developed systems that allow darker colours to be used, though we generally prefer to stick to lighter colours for plaster and recommend other cladding products as more suitable where a client wishes to use a darker colour. Plaster can be a bit plain looking when used on an entire house, so we will often use it in conjunction with another cladding such as timber that has a bit more textural interest.
Timber is one of our favourite cladding materials, which you probably already know if you’ve had a look through our portfolio. It’s also a material that most builders love working with. So what is it that makes natural timber such a popular cladding material?
One reason is that timber fits in very sympathetically to the surrounding landscape – it’s colour and texture don’t compete with the background of trees and bush in the same way that painted or high contrast materials can.
Timber cladding is also a great way for skilled builders to show off their craft – there’s no filler or paint applied afterwards, so every cut and joint needs to be made with care. The boards can be run horizontally (bevel backed or rusticated) or vertically (shiplap), and there are different board profiles and surface textures available that can create anything from traditional to modern styling.
By far the most common timber cladding in recent years has been western red cedar, which is imported from western North America. Cedar is a very stable timber, which makes it particularly suitable for use as a cladding where it will be exposed to sun, wind and rain.
We are also starting to make increased use of other timber species as cladding materials, such as Siberian larch, recycled Australian hardwoods, and even NZ-grown radiata pine that is heat-treated to enhance its durability and stability.
Each timber has a different appearance, and it is important to be aware of the variations between, and even within, different products so you can make an informed choice. The most important thing to be aware of is that timber is a natural product, and there will always be a degree of variation in colour, grain and texture between different boards.
As an example, the colour of western red cedar can vary from pale straw brown through to almost chocolate brown – this variation will show through most lighter oil stain finishes, so if you are after a very consistent cladding colour then it would be best to use a very dark stain colour or select a different species of timber.
Siberian larch has a very knotty finish which could look great if you are after a rustic style, but if this isn’t to your liking you may be better off selecting a product such as modified pine that is manufactured to give a very regular look.
Timber is a relatively expensive option for use as a cladding, and because most of the timber used for cladding is imported into New Zealand it’s pricing as a commodity can fluctuate depending on international supply and demand. If cost is an issue then it can be useful to use a limited amount of timber alongside a more cost-effective cladding.
Timber is also a product that required a considerable amount of maintenance – most oil stains will require reapplication after a year or two, and then every few years after that. For this reason, it is important to ensure that there is easy access available where timber cladding is used, otherwise, the costs of scaffolding will quickly mount up over the life of your home.
Where corrugated metal cladding is a cheap material and quick to install, metal panel cladding uses metals that are much more expensive to supply and installation methods that are much more time-consuming. The finished product however can be absolutely stunning. Three types of metal panel cladding are:
Metal claddings are generally very low maintenance, and some metals can develop an attractive patina as they age. Copper for example quickly turns a rich brown colour and will turn green over time. Some combinations of different metals and/or timbers can lead to corrosion that reduces the durability of metal cladding, so it is important to take care to ensure that metal cladding is compatible with everything it is in contact with, including fixings and even water runoff from other materials.
Powdercoated finishes are a good way of achieving a coloured coating that is much more durable than a paint finish, and we often use such cladding on upper levels as an alternative to painted board cladding to eliminate regular maintenance where access is restricted.
Aside from its use as concrete blockwork, concrete can also be used in precast panels as both the structure and cladding of external walls. This sort of system is used extensively in commercial buildings, but there are a range of finish and colour options that can be used to create a refined appearance for residential architecture. For example, the surface can be acid etched or sandblasted to soften the texture, or there are pigments that can be added to the concrete mix to achieve darker colours or brighter whites.
There are a few options for achieving insulation when using precast panel walls. The simplest way is to line the inside with framing and insulation to keep the cold concrete on the outside. If you like the appearance of solid concrete on the inside of the walls as well the concrete panels can be formed with a layer of insulation in the middle to separate the outer and inner layers of concrete, this allows you to take advantage of the thermal mass to help make the most of thermal gain during the day in winter months, or to help the house stay cool in summer.
The cost of concrete panels can vary widely depending on factors such as surface finish, modular construction (i.e. is the same panel shape used repeatedly or is every panel different?), and ease of access to crane panels into place. It’s not suited to every location, but can be a great option for the right project.
Stonework can be one of the most expensive claddings to use, largely due to it requiring skilled craftspeople and lots of time to assemble. There are many different types of stone available for use, so we’ve described some of the different installation methods below along with some of the different stone types that may be suitable for each.
The simplest way to install stone is when it is cut into regular blocks and installed using a similar method to bricks or concrete block over timber framing. You’ve probably seen plenty of Oamaru stone installed in this way – this is a limestone with a creamy white colour. We have also used Hinuera Stone cladding installed in the same way, this is a volcanic stone from the Waikato region that gives some other options for colour and texture.
The same regular block look can also be achieved using thinner stones, for example Timaru Bluestone can be installed on a free-draining clip system.
If you are after a more traditional or random finish then the stones are usually installed against either a solid concrete backing or a solid panel with a drained cavity behind it. There are plenty of options available – schist has always been popular, though it is worth speaking to a stonemason to find out what local stones are available as these may suit your site better than a stone that has been shipped in from other parts of the country. Canterbury has a great source of river and volcanic stone that can be put to great use in the hands of a skilled craftsperson.
Stone is generally a very low maintenance cladding. Occasionally you will see stonework that is stained by efflorescence, which is when salts leach out of the mortar that is used to hold the stones together. While this can be cleaned off with a stiff brush and/or chemical treatments, it’s best to prevent the problem from occurring in the first place by using appropriate flashings and sealant coats to prevent the mortar from getting wet.
Trying to find the best cladding for your new home but aren’t sure where to begin? Give Chaplin Crooks Architects a call and discuss your cladding and construction materials today.