Weatherboard cladding does more than just make your home look good. It serves as the primary defense against the elements for your home, protecting it from whatever type of weather your area experiences throughout the year. If you choose the wrong cladding material for the conditions in your area, the consequences can be expensive to remedy.
Moisture and Coastal Exposure
If your house is in a high-rainfall region or near the coast, the risk factor embedded in timber weatherboards is real. And wood’s natural porosity also makes it a potential victim of moisture as the fibers soak up the rain, causing the boards to swell, and ultimately developing the sort of fungal decay that hollow-sounds when you tap it. Salt-air conditions wreak even more havoc. The tiniest imperfection in the factory finishes of timber weatherboards across your whole home, and you’re looking at salt air carrying that directly into the timber then breaking its skin. Salt and moisture, as good as we think we seal them in, are brutal on any substrate. And paint or stain maintenance is not a job you want to double down on in a marine environment.
Fiber cement, because it doesn’t absorb water, is less affected by all this, though the product is heavy, and if not expertly painted in the first place, can become a maintenance nightmare and prone to cracking at the fixings if it does move.
uPVC resists all these problems. It’s entirely without porosity, so moisture can’t penetrate the surface, and as a result, it’s extremely resistant to all kinds of decay including salt damage. uPVC doesn’t and won’t rot, it’s not appreciably degraded by salt spray or UV, and its color is ‘through’ the product (i.e., it’s the same all the way through, not a thin surface veneer), so minimal maintenance is required over its long lifespan. For coastal builds especially the material choice here isn’t really a style preference. It’s a structural decision.
UV Exposure and Color Retention
Sunlight is a major degrader of external building products. The more constant, direct, and high the sun the more stress materials are put under. UV radiation is the major cause of and accelerator of surface degradation. With the southern hemisphere having the strongest UV conditions, products must be resistant, or they will degrade rapidly, especially in the hottest, sunniest locations in our country. Many cheaper synthetic cladding products can degrade rapidly in high-sun conditions becoming brittle and losing color in only a few years.
Many cheaper synthetic cladding products do not have enough, or have the wrong sort of UV stabilizers in them. UV stabilizers work by either absorbing the UV radiation that breaks down the chemical chains in the polymers, or by reflecting the UV radiation. Some artificial claddings are designed to perform in European conditions and have not been designed to resist the harsh Australian conditions.
The lack of proper UV stabilizers can be seen after the product has been in the sun for a few years, often by the product losing its glossy finish and becoming chalky to the touch. UV stabilizers are not an optional extra; no reputable manufacturer uses less than the optimum levels. UV stabilisation can reduce the impact of UV radiation by 90% but only the right type of UV stabilisation can give you long life. UV stabilised Formplex cladding products have proven durability in real high UV building conditions.
Thermal Performance in Extreme Climates
Heating and cooling systems contribute to about 40% of the average energy use in a household (Australian Government YourHome guide). With that information, you’ll see how important cladding can be. If your wall assembly allows all that expensive climate-controlled air to escape, or hot outside air to rush in, you’ve got a problem. Energy savings from installing or upgrading your house cladding can be quite significant. If you’re building new, a design that incorporates a cladding material’s natural insulation properties means you can choose smaller, cheaper heating and cooling systems.
The R-value of cladding, that’s its resistance to heat flow, can vary drastically depending on the material and the installation. For instance, uPVC cladding is a hollow profile containing an amount of trapped air that provides a small amount of built-in insulation. Many uPVC products are also available with foam backing, yielding higher thermal performance. For installations where you face freezing winters and/or searing summers, the insulation backer contributes to lower loads on your heating and cooling systems. Lower input loads translate to cheaper ongoing energy costs which, of course, increase with every energy price hike.
Bushfire Rating Compliance
If your property is located in a fire-prone area, the Bushfire Attack Level (BAL) rating of your home will determine which materials you can and can’t use. You don’t get to decide whether or not you pay attention to this rating. It’s not your call. Flouting it forces you to assume the risk of making your home more dangerous and potentially take on more liability if something goes wrong.
Higher BAL rating automatically exclude or severely limit the use of untreated timber, and also set out minimum performance requirements for the entire cladding assembly. There are fire-rated fiber cement options available that qualify for use in some of the most stringent situations, and depending on the specific formulation and construction of the wall assembly, some uPVC cladding products may also meet the standards. But you need to reference the actual product certification for the design, not just the material type. This can be different from one manufacturer to the next, even within the same product line.
The Real Cost of Maintenance Over Time
More affordable materials are rarely if ever cheaper over the lifetime of your home. Timber weatherboard cladding may look like a purse-pleaser per square meter, but when it needs repainting or resealing every five to seven years (or more frequently in areas of high exposure), the costs of scaffolding, labor, and resurfacing add up. Synthetic products will rarely demand more than a hose-down to look their best. The carbon footprint of both manufacturing and maintenance is also considerably lower.
