Choosing the right frame for a greenhouse is really important if your greenhouse is to provide you with the growing facility and life span you are looking for. Before deciding on a greenhouse frame material you should also consider where you are planning to erect it and what you are hoping to grow in it.
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The main types of material used for greenhouse frames are wood, aluminium, steel and plastic/ PVC. Here we look at each frame material and what you should consider before choosing one.
The traditional option for a greenhouse frame is wood. Wooden frames are affordable and relatively easy to maintain.
If you’re looking for a sturdy frame that will last for many years, wood is a good choice. However it is important to make sure that the wood is pressure treated and sealed with a waterproof sealant or paint to protect it from the elements.
Steel frames are the most durable option, but they’re also the heaviest and most expensive. They are a good choice if you live in a cold climate, as steel which is usually galvanised is not affected by extremely cold temperatures.
As steel frames are so strong you will need fewer beams to support your structure. One of the benefits of fewer beams and frame structure is that you can have more clear panels and therefore more light.
Additionally galvanized steel is thermally conductive and so heat is transferred quickly and evenly throughout the frame, which helps keep your plants warm in the winter.
The main drawback you will find when using a steel greenhouse frame is that often they are made to be used with polyethylene film rather than glass or polycarbonate. If you are serious about growing plants this option usually in the form of a poly tunnel may be a good option. But if you are looking for a more decorative structure a frame for a traditional glass or PVC panel option may be better.
Aluminium frames are a good option if you’re looking for a lightweight but durable frame.
Aluminium is less expensive than both steel and wood frames so the most budget friendly choice. Aluminium is also corrosion resistant and so doesn’t rust, making it a good choice for coastal climates.
Aluminium greenhouse frames have a number of benefits that make them a popular choice for greenhouse owners.
In addition to not corroding they are very lightweight, which makes them easy to move around. They are also good at conducting heat, which means that they can transfer heat from the sun or a heating unit, quickly and evenly throughout the frame, keeping plants warmer in cold weather.
One of the downsides of an aluminium frame is that it can be difficult to find much choice in frame sizes.
Plastic PVC are A low cost, lightweight option for a greenhouse frame and are usually easy to assemble. Plastic frames also have the advantage of allowing less heat loss than aluminium or steel.
Greenhouses with plastic frames do tend to be smaller and usually have polyethylene walls. Most hobby greenhouses sold in kit form now have PVC frames. So if you plan to use your greenhouse for serious growing this may not be the right option.
Perhaps the main disadvantage of a plastic greenhouse frame is that sunlight can deteriorate them. So you should always choose a PVC frame that is UV protected with this protection they should last for at least 20 years.
The frames also tend to be wider which is necessary to compensate for their reduced strength. This means a reduction in the size of the clear panels and therefore less light potentially.
However It’s not as durable as the other greenhouse frame materials we’ve discussed in this guide, but it’s a good choice for hobbyists or people who only plan to use their greenhouse occasionally.