Both frame materials are used on excellent greenhouses, and the choice between them is genuinely a matter of what you want the building to be. 🪵 Aluminum asks nothing of you and looks contemporary. Wood asks for a weekend every few years and gives back warmth no metal produces.
That is the honest headline. Here is everything underneath it, with the drawbacks of each stated as plainly as the advantages. ⚖️
🪞 Aluminum frames
What they genuinely do well
- 🛡️ No maintenance, ever. Aluminum forms its own oxide skin and then stops changing. Anodized or powder-coated, it neither rusts nor rots. Expect twenty-five years and up, with the finish dating before the metal does, as we set out in how long does a greenhouse last.
- 🔆 Slim sections, more glass. Aluminum extrusion can be thin and still strong, so the glazing bars are narrow. On the same footprint you get noticeably more glazed area, which means more light and a lighter-feeling interior.
- 💨 Straightforward to engineer for wind. Extruded profiles are consistent and predictable, which is why aluminum structures carry high published wind ratings, ours at 115 mph.
- 🔩 Integrated glazing channels. The profile itself holds the glass, so assembly is faster and panes are simpler to replace.
- 🏗️ Lighter to handle during a build, which matters more than people expect on day two.
Where it genuinely loses
- 🧊 It conducts heat. Metal glazing bars are thermal bridges, so an aluminum frame loses more heat per linear foot than wood. On a heated structure this is a real running cost.
- 💧 Condensation on the bars. Cold metal in a humid greenhouse drips. Good profiles include condensation channels; cheap ones drip onto whatever is below.
- 🏛️ It reads as equipment, not architecture. This is a matter of taste rather than a defect, but if you want a garden building that looks like it belongs beside a period house, aluminum has to work harder.
- 🔧 It cannot be repaired. A damaged extrusion is replaced, not mended, and it can only be modified in ways the profile allows.
- ⚠️ Thin gauge is a real weakness. Aluminum is less stiff than steel for the same section, so a cheap thin-wall aluminum frame is genuinely flimsy. Most of the price variation within aluminum is gauge.
🪵 Wood frames
What they genuinely do well
- 🌡️ Wood insulates. It is a poor conductor, so the frame is not a thermal bridge. A wooden greenhouse holds heat better than an aluminum one of the same glazed area, and the bars do not stream with condensation.
- 🏡 It looks like a building. This is the actual reason most people choose it. A wood frame reads as garden architecture, sits comfortably next to older houses, and is far more likely to pass an HOA materials clause.
- 🔨 It is repairable. A rotted sill can be cut out and replaced with a saw and a weekend. Nothing in aluminum works that way.
- 🔩 You can screw into it anywhere. Shelves, hooks, benching, a hanging basket. On aluminum every fastener needs a channel or a bracket.
- 🧱 Substantial sections feel solid in wind and dampen noise in a way thin metal does not.
Where it genuinely loses
- 🖌️ It needs treating, and this is not negotiable. Every two to four years depending on climate and finish. Skip it for a decade and the decade is what costs you.
- 💪 Thicker bars, less glass. Wood needs more section to carry the same load, so glazed area on the same footprint is lower. A little less light, a slightly heavier-feeling interior.
- 💧 It fails at the bottom. Almost always where the wood meets a damp base. Detailing the sill above standing water matters more than the species.
- 💰 It usually costs more for a comparable structure, and the shorter warranty terms across the industry reflect the maintenance dependency rather than a quality gap.
- ⏳ Lead times run longer. Our wood-framed range takes roughly ten to twelve weeks against four to six for polycarbonate models.
🌲 Which species, and why it matters
"Wood" covers a wide range of outcomes. 🪵
- 🌲 Spruce and pine. The common choice, affordable and strong, and entirely dependent on treatment. Untreated softwood in contact with damp ground can be finished in eight years.
- 🌳 Cedar and redwood. Naturally durable oils resist rot without preservative. More expensive, and they still benefit from a finish if you want to keep the color rather than let it silver.
- 🧪 Modified woods such as Accoya. Softwood chemically modified to be dimensionally stable and rot-resistant, with very long service expectations. Expensive, and the reason it appears as an option rather than a standard.
The other variable is the finish. A penetrating oil is easy to refresh and never peels but needs doing more often. A film-forming paint or stain lasts longer between coats but must be stripped when it eventually fails. Neither is wrong; pick the maintenance rhythm you will actually keep. 🖌️
🧭 Choosing between them
- 🏢 You want zero maintenance: aluminum, without hesitation.
- 🏡 The building has to look right next to an older house: wood, and it is usually not close.
- 🔥 You intend to heat it: wood has a real thermal advantage, though glazing choice matters more than frame material here.
- 🔆 Maximum light on a constrained footprint: aluminum, for the slimmer bars.
- 💨 Very exposed, high-wind site: check the published rating rather than the material. Both can be engineered for it, and only the number tells you which one was.
- 📋 Strict HOA materials clause: wood passes review more often, which we went through in our HOA guide.
- 🗓️ You are honest that you will never treat it: aluminum. A neglected wooden greenhouse is a worse outcome than a metal one you never think about.
That last point is the one we would press hardest. The right question is not which material is better but which maintenance profile matches how you actually live. 🤝
🧾 What the warranties tell you
For a benchmark you can compare against: our aluminum-framed glass range carries a 12 year warranty and the wood-framed range 5 years. 📄
That gap is not a quality ranking. It reflects the fact that a wooden structure's life depends on an owner action nobody can guarantee, while an aluminum frame's does not. A maintained wooden greenhouse comfortably passes twenty-five years. An unmaintained one does not reach ten. The warranty is priced against that uncertainty. ⏳
🔍 And the third option nobody puts in this comparison
Galvanized steel, which frames most polycarbonate structures. It is stiffer than aluminum per section, cheaper for the same strength, and effectively maintenance-free apart from touching up scratches with cold galvanizing paint. 🧱
It is not usually compared here because it belongs to the growing-tool category rather than the garden-room one. If your priority is floor area per dollar and season extension rather than how the building looks, that is the family to be looking at, and the difference is set out in our polycarbonate versus glass guide. 🌱
❓ FAQ: aluminum and wood greenhouse frames
Which lasts longer?
Aluminum, if nobody does anything. Twenty-five years and up with no intervention, against eight to twenty-five for wood depending entirely on treatment. Maintained wood closes the gap almost completely. ⏳
Is a wooden greenhouse warmer?
Yes, measurably. Wood does not conduct heat the way metal glazing bars do, so there is no thermal bridge and much less condensation on the frame. Glazing type still matters more overall. 🌡️
How often does a wooden greenhouse need treating?
Every two to four years, depending on climate and finish, and before it looks like it needs it. Oils are quicker to refresh, film finishes last longer but eventually need stripping. 🖌️
Do aluminum frames rust?
No. They can suffer galvanic corrosion where dissimilar metals touch, which good structures avoid by isolating them, but aluminum itself does not rust. 🛡️
Which is better for a small yard?
Usually wood, and for an unexpected reason: in a small yard the greenhouse becomes the main visual event, so how it looks matters more than in a large one. 🏡
Can I paint an aluminum frame?
Yes, with the right preparation and a suitable primer, though a factory powder coat will always outlast a repaint. Choosing the finish at purchase is the better route. 🎨
🌿 Our summary
Neither material is the compromise. Aluminum is the correct answer for people who want the building to be invisible in their maintenance calendar and maximally glazed. Wood is the correct answer for people who want a garden building with presence and are content to give it a weekend every few years. 🧭
If wood appeals, a structure like The Homestead shows what solid wood and tempered glass look like at scale.
Whichever way you lean, compare the published numbers rather than the photographs. Every model in the Prime Greenhouses range states frame material, glazing type, wind rating and warranty term on the page. 📊