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Greenhouses are designed for one purpose, and that is to provide a protected environment for plants to grow. But apparently, the material used to build one can make a difference in terms of thermal efficiency and maintenance.
In this guide, we’ll look at how wood and metal differ and see which stands out best. This could be useful if you’re thinking of investing in one soon, so keep reading!
Wooden Greenhouse Features
Wood on its own is a fantastic building material for garden structures, including greenhouses. It has a great strength-to-weight ratio—better than steel, in fact. Not to mention its insulating properties.
Below are some of the wooden greenhouse’s key features, along with a few quirks to consider. This should help you decide if one could be the right choice for you.
Thermal efficiency of a wooden greenhouse
Wood is a natural insulator with a lower thermal conductivity. That’s because of its cellular structure, with air pockets that keep heat from escaping so quickly and slow down how quickly it transfers. This allows the temperature inside the greenhouses to be warmer than the air surrounding them. This keeps them warm in winter and reduces excessive heat build-up in summer.
The need for extra insulation won’t be as crucial as it is for poor insulators like metal (we’ll get to that later). However, simple additions like bubble wrap or shade cloth can help in extreme weather if you want to improve efficiency further.
Maintenance of a wooden greenhouse
Wood is strong but can be vulnerable to rot and decay if left untreated or not given much TLC. That’s where pressure-treated options come in—it’s a treatment that outperforms untreated ones. It works by infusing the wood with chemical preservatives, resulting in wood that’s resistant to insect damage, moisture, and rot.
Luckily, wooden greenhouses come pressure-treated as standard or offered as an upgrade at a worthwhile cost. It’s worth it because it saves you the hassle of treating the wood yourself. Even better, it comes with an extended guarantee for up to 15 years.
What this means for you is that you won’t need to apply treatments as often, and the structure will last longer with minimal upkeep.
Metal Greenhouse Features
Metal, especially aluminium and galvanised steel, is great at handling harsh weather like strong winds and heavy snow. But like any material, it has its drawbacks, too. Here’s what you need to know:
Maintenance of a metal greenhouse
Aluminium doesn’t rust, which is a huge benefit for greenhouses that receive constant moisture and humidity. It is also resistant to rot and pests and does not need to be painted or sealed like wood. In fact, little to no maintenance required!
The same applies to steel greenhouses, particularly those with frames coated in zinc (galvanised steel). This coating makes them resistant to corrosion and rust, making them even easier to maintain.
Thermal efficiency of a metal greenhouse
On the downside, metal has poor thermal efficiency due to being highly conductive. When used as framing in a greenhouse, the structure quickly transfers heat, causing the internal temperature to fluctuate more than in a wooden greenhouse.
The good thing is that this can be remedied by adding insulation or installing a thermal break. For the latter, apply it between the metal frame and glazing to slow heat transfer. If the structure has roof vents, simply open them to improve ventilation and prevent overheating. Keep in mind, though, that these upgrades may add to the overall cost.
Moreover, some units are designed not to be fully metal-framed or glass-panelled. Instead, they feature aluminium framing with polycarbonate panels. Why is this an improvement, you ask? Polycarbonate panels provide better insulation than glass. While aluminium is still a conductor, these panels also help minimise the rapid temperature fluctuations that occur with glass. These panels are also harder to break than glass.
An excellent example is the BillyOh Rosette Hobby Aluminium Polycarbonate Greenhouse. It’s designed with a tough aluminium frame and twin-wall polycarbonate glazing panels to make the most of the sun. The opening roof vents ensure great air circulation throughout the year.
The Verdict
A wooden greenhouse has the upper hand when it comes to thermal efficiency. In contrast, a metal greenhouse conducts heat more readily, leading to greater temperature fluctuations. However, polycarbonate panels can help improve insulation.
In terms of maintenance, those made of metal require less upkeep. Timber-made ones, meanwhile, need regular care, but pressure-treated options help reduce upkeep needs.
Both options can be great as long as you’re willing to invest a little extra. A wooden greenhouse offers better insulation, but you may need to pay for pressure treatment or apply treatments yourself to keep it in top shape. A metal greenhouse requires less maintenance, but adding insulation can help manage temperature fluctuations.
FAQs
Why does thermal efficiency matter in a greenhouse?
Keeping a steady temperature is key for healthy plant growth. A well-insulated greenhouse helps with this, meaning less need for extra heating or cooling, which can also save on costs.
How does maintenance affect how you use your greenhouse?
The more upkeep it needs, the less time you have for planting. A low-maintenance greenhouse lets you focus on growing, while a higher-maintenance one means more time spent on repairs and treatments.
Does pressure treatment affect a wooden greenhouse’s insulation?
No, pressure treatment protects the wood from rot and pests but doesn’t change its ability to keep heat in or regulate temperature.
