A pergola is a very simple outdoor structure made up of four legs and slats that create a roof. These structures are a good choice for use over an outdoor seating area, where you might need some protection from the sun, but don't want to have full shade over that space.
Pergolas can also be purely decorative, adding some visual interest to an otherwise "dead" corner or space of your yard. Before you choose a pergola for your property, however, note a few simple but very important details you'll want to consider, so you opt for the right materials and style for this structure, and are happy with the piece once it's erected.
Wood is very attractive and natural and may be the best-looking material for a pergola, but wood also requires the most maintenance, as it will absorb moisture and then expand and shrink, and also fade over time. You might need to reseal or otherwise treat a wood pergola more than any other material, so consider this maintenance work if you're thinking of wood. Opt for aluminium if you want something more durable and that needs virtually no maintenance over time.
On the other hand, if you want to plant climbing vines around the pergola so that they grow and fill out the walls or ceiling space, wood might be the best host for them. A metal pergola might get overly warm during the summer, and then also bitterly cold during winter, which could be damaging to your greenery. Wood also provides some moisture for those vines, keeping them hydrated and healthy. While climbing vines may actually cause indentations on the wood over time, they may not grow very well on a metal framework, so choose wood if you want to add vines on the pergola itself.
If you're having a pergola built to provide shade for a patio area, you might want something very large and expansive. However, a larger structure may need deeper anchors for the posts, and may be more difficult to put together yourself, so be prepared to use a pergola builder for a large structure.
For smaller structures, you also need to consider those climbing vines, mentioned above. Very full greenery, such as grape leaves, can easily close off the structure and make the space under the pergola seem a bit claustrophobic. Either expand the framework of the pergola, or opt for smaller vines that aren't so full, such as morning glory or black-eyed Susan.