Timber looks better on the day it goes up, and for a couple of years after that. Then the maintenance starts, and the two materials go their separate ways. Aluminum does not rot, does not split along the grain and does not feed termites, and a powder-coated frame holds its finish through years of sun. The honest caveats run the other way too: aluminum gets hot to touch, rain on it is loud, and it will never give you the warm look of a timber beam with something climbing over it.
See our aluminum louvered pergola
The first two years
If you judge on year one alone, timber wins and it is not close. A hardwood beam has a depth to it that painted metal does not, it suits older houses and planted gardens, and it feels good under a hand. Aluminum reads clean and modern. In the right setting that is exactly what people want, and in the wrong setting it looks like office landscaping.
By year two or three the timber has started to grey, or it has started to need you. Which of those happens depends on whether you oiled it, and how much sun and rain it takes.
What actually fails on a timber pergola
The post bases. Ground contact and splashback wick moisture up into the end grain, and rot starts where you cannot see it. This is the single most common reason a timber pergola gets replaced.
Then the top surfaces. Horizontal rails and rafters take the full force of the sun, and timber splits along the grain as it dries and wets in cycles. Beams twist. Once they twist, joints that were tight are no longer tight and the structure starts to look tired.
In warm states you also have insects. Termites and carpenter bees are both real and neither is a warranty conversation.
On top of that is the recurring work: cleaning, sanding, and restaining or oiling every couple of years. Some owners enjoy that. Most of them stop doing it around year four, which is when the decline becomes visible.
What ages on an aluminum frame
Powder coating is a hard, baked-on finish, and it holds up well against UV. Over a long time it will chalk slightly and lose a little of its gloss, more so in intense sun. It will not peel the way paint does, and it does not need redoing on a schedule.
What does need attention is mechanical rather than material. The drainage channels inside the beams collect leaves, and blocked channels cause overflow. Fittings should be checked once a year. A scratch through the coating near the coast can start corrosion underneath, so rinse the frame more often if you are within a few miles of salt air. And blades will dent if something heavy falls on them, which timber shrugs off better.
Aluminum is not maintenance free. The list is just much shorter than the timber one, and nothing on it involves a sander.
Heat, sound and how each feels to sit under
Aluminum conducts heat. Blades in direct summer sun get hot enough that you would not want to rest a hand on them, and a closed roof radiates some of that downward, which is why airflow through partly open blades matters so much. Timber does not behave that way. It stays closer to air temperature and feels better to touch.
Rain is the other difference you notice immediately. Water on aluminum is a drum. Water on a timber slat roof is closer to nothing. Under a bedroom window, or in a courtyard where sound bounces, the metal roof is the one you will hear.
Repair and modification
Timber can be cut, drilled, notched and scribed on site. If a post is 20 mm out of place, someone with a saw fixes it in an afternoon. That flexibility saves a lot of installations.
Aluminum cannot be modified meaningfully on site. Dimensions are set at the factory, which is why measuring carefully matters so much more, and why we ask for your site numbers before anything goes into production. The flip side is that a factory-built frame arrives square and stays square.
At end of life, aluminum is straightforwardly recyclable. Preservative-treated timber cannot be burned and often cannot be easily disposed of.
Which one fits your house
Pick timber if you want a garden structure, you like the material, and you are willing to maintain it or accept that it will weather. Pick aluminum if you want a shelter that behaves the same way in year ten as it did in year one, and you do not want a recurring weekend job.
Matching the house matters more than people admit. A contemporary aluminum frame against a brick Edwardian terrace is a fight you will lose.
Frequently Asked Questions
Does an aluminum pergola get too hot to sit under? The blades do get hot in direct sun, yes, and a closed roof radiates some of it. Leaving the blades partly open lets hot air escape through the gaps, which is what most owners do in summer. Full closure is for rain.
Does powder coating fade? It holds colour well under UV and will slowly lose gloss rather than fade in patches. It does not need repainting on a schedule the way stained timber needs redoing.
Is timber a bad idea near a pool? Chlorine and constant splashing are hard on it, and so is the humidity. Aluminum handles both better. Rinse the frame more often if you are close to the coast, where salt air does the same kind of work.
Can I paint an aluminum pergola later? You can, but powder coating is a factory finish and paint over it rarely bonds as well. Choose the colour at order time, since it is a custom frame and not something you repaint on a whim.
Does an aluminum pergola need a stronger footing because it is lighter? Not stronger, but anchoring matters more. A light structure resists wind by being tied down rather than by its own weight, so the fixings into the base are what hold it.
Is aluminum maintenance free? No. Rinse the blades, clear the drainage channels when the trees drop, and check the fittings once a year. What it is free of is sanding, staining, sealing and termite inspections.