Leon Chen
Mar 7, 2019
New Zealand, an island nation in the southwestern Pacific Ocean, has a predominantly temperate maritime climate with mild temperatures year-round. The main functions of exterior walls are rain protection, sound insulation, heat insulation, and aesthetics. Which exterior wall material is more advantageous in New Zealand's relatively humid climate? And which material is more durable and cost-effective to maintain? Today, we'll discuss exterior wall materials for houses in New Zealand. Generally speaking, there are five main types of exterior wall materials used in New Zealand: Weatherboard, Cedar, Brick, Fibre Cement, and Plaster.
Weatherboard is a type of wood panel. Its advantages include affordability, availability in various sizes, low leakage risk, and decent insulation. However, with the increasing scale of building development and housing demand, and the slow-growing nature of the wood used for weatherboard, supply has fallen short of demand, leading to a shortage and rising prices. Furthermore, the insulation performance of weatherboard is not as outstanding as other exterior wall materials. Among the many misconceptions about weatherboard, the "leak-proof myth" is most likely to mislead buyers. While weatherboard does offer better water resistance than older materials, wood is prone to rot and is susceptible to damage from dark paint. Dark-painted wood exteriors are prone to warping after exposure to sunlight, leading to leaks. Significant disadvantages of weatherboard include its lack of fire resistance and its relatively soft texture. It also requires frequent maintenance, potentially increasing property upkeep costs. In the past, weatherboard was sourced from mature, dense trees. Today, it is often made from fast-growing, porous wood, making it highly susceptible to mold growth in humid environments. If the wood paneling cracks, you'll need to hire someone to repair it, and considering New Zealand's high labor costs, you can imagine how expensive repairs can be. Take Mr. Wan, a Chinese buyer in Albany, for example: the wood paneling needs maintenance approximately every 4-5 years. City regulations stipulate that for two-story houses (over 1.9 meters high), scaffolding must be rented for maintenance. Including labor costs, a single maintenance appointment could conservatively cost 5,000-6,000 New Zealand dollars.
Redwood (Cedar) is also known as cedar. Redwoods are fast-growing, have a high survival rate, straight trunks, thick bark, and strong insect and fire resistance, making them recognized as one of the most economically valuable tree species in the world. Due to its ease of cutting, nailing, and gluing, it was commonly used by builders in the early 1920s for exterior walls, decks, fences, etc. Although it has gradually fallen to a secondary role due to the emergence of new materials, using redwood for exterior walls still reflects the homeowner's refined taste and financial status. Redwood's advantages include its natural anti-corrosion properties, making it one of the few wood materials that can be used without processing, and its excellent sound insulation and heat insulation properties. However, like weatherboard, cedar needs maintenance every 5 years. It requires thorough cleaning and application of a special protective coating for wood, especially in areas close to the ground or vegetation, and in shady areas of the house. Wood is prone to becoming brittle, moldy, corroded, or damaged when exposed to moisture for extended periods, which can affect the appearance and stability of the house.
Brick | It's easy to imagine that brick is a favorite exterior wall material among Chinese people. Firstly, it looks very sturdy; secondly, brick has excellent thermal insulation properties, an advantage that is even more pronounced in damp, cold winters. Additionally, if brick is damaged, it's very easy to replace the damaged part. Of course, brick also has limitations. For example, when calculating the area of a house, the brick must be included. Therefore, for a house of the same size, if brick is used for the exterior walls, its interior area will be at least 5% smaller than if other materials were used. The disadvantages are also obvious: the labor cost for installing brick is higher, and the construction time is longer. The style selection is also more conservative.
Fiber cement board is a new type of cement material suitable for both interior and exterior building applications. It boasts excellent impact resistance, moisture resistance, and fire resistance, while maintaining low maintenance costs. Suitable for various indoor or semi-outdoor building uses, it maintains high stability even under repeated exposure to damp environments. Furthermore, although it's cement, fiber cement doesn't have the monotonous color of traditional cement, bringing a bright and simple design to buildings. However, fiber cement boards have a very long lifespan, and considering future maintenance costs, they may be a more economical choice. Many fiber cement boards can typically last around 12 years with minimal maintenance. Therefore, in the long run, the overall cost of fiber cement boards is definitely lower. As a high-tech composite material, fiber cement boards also have significant advantages in other aspects. For example, in terms of fire resistance, fiber cement boards can withstand open flames for an astonishing 60 minutes. Many consumers believe that bricks are the cheapest option, but compared to fiber cement boards, bricks still have high maintenance costs. Because bricks contain a large amount of salt during the firing process, after the rainy season and exposure to sunlight, all the salt will seep into the wall. In fact, each exterior wall material has its own characteristics and advantages. When choosing, you should select the material that best suits your needs. However, overall, fiber cement board is probably the best exterior wall material, unmatched in the entire New Zealand building materials market.
Plasterboard | Plaster Finally, let's talk about plaster walls, which many people avoid. When it's mentioned, most people immediately think of leaky houses. The reason plaster walls cause such panic has historical reasons. From the early 1990s to 2003, the New Zealand government considered untreated wood more environmentally friendly, allowing the use of untreated wood for timber frames. This building code led James Hardiest, a major plaster manufacturer at the time, to produce a new plaster material—HardiTex. This material was widely used due to its simple installation process and modern appearance. However, plaster is completely waterproof. Once water gets into the joints, it's difficult for it to escape. Over time, the wood inside begins to breed insects and mold, and begins to rot. Furthermore, the timber frames at the time were not treated with preservatives, making them even more susceptible to decay and deterioration when combined with this wall material. Additionally, because plaster is relatively hard and does not easily expand and contract with temperature changes, cracks easily appear at the joints. Without regular maintenance to seal the cracks and repaint, leaks are very likely to occur. Another point to note is the balcony of a house with this type of exterior wall. If there's a metal handrail directly inserted into the plaster, there's almost certain to be a risk of leaks. However, it's important to emphasize that there's no need to completely avoid plaster exteriors. Since 2004, due to new building regulations introduced by the New Zealand government, all plasters are required to have a cavity system and use preservative-treated wood. Therefore, plaster houses built after 2004 don't have as many problems.