Greenhouse kits and what they cost: polycarbonate vs glass, kit vs DIY
Greenhouse pricing looks chaotic until you break it into 2 numbers: the glazing (the clear walls and roof) and everything that holds it up. Get the glazing choice right and the rest follows. The headline figure is that building a greenhouse runs roughly $5 to $35 per square foot, a 7-fold spread that comes down almost entirely to whether you glaze in film, polycarbonate, or glass and whether you buy a kit or build it. This guide puts real prices on each path – a polycarbonate greenhouse kit versus a glass one, a kit versus a DIY build – and gives you a per-square-foot budget you can size to your own plan. If you have not settled on a shape yet, start with the greenhouse style that fits your site; if you mean to grow through winter, the cold-climate build in a four-season greenhouse changes the glazing math.
Polycarbonate vs glass: the glazing decision
The glazing is the single biggest driver of both cost and warmth, and for a home greenhouse the choice is really twin-wall polycarbonate against glass. They trade off on 4 things: light, heat, durability, and price.
Light and heat
Glass passes the most light – around 85% to 90% – and stays optically clear for decades, which is why it still defines the classic glasshouse look. Polycarbonate is close behind at about 87% for a twin-wall sheet, per University of Georgia data, and it scatters that light evenly so plants get fewer hot spots. On heat the gap flips hard in polycarbonate’s favor: a single pane of glass runs about R-0.9, while a 4-wall polycarbonate panel reaches roughly R-2.1 – so the glass loses heat about 2.3 times faster. The hollow air channels that make polycarbonate look cloudy up close are exactly what make it the warmer wall, and on a winter heating bill that difference compounds night after night.
Durability and price
Here the materials split on character. Glass lasts 25-plus years, often 40 with care, but it is heavy and shatters – a hailstone or a thrown ball can take out a pane, and a broken pane means falling shards over the beds. Polycarbonate carries roughly 300 times the impact resistance of glass and will flex or dent rather than break, though its panels cloud and yellow over a 7-to-20-year life and eventually need replacing. On price, polycarbonate is the value pick: about $1.60 to $3 per square foot against $2.50 to $3.50 for glass – roughly half the cost for the warmer material. For a grower weighing a tight budget against decades of service, that split is usually the whole decision.
| Factor | Twin-wall polycarbonate | Glass |
|---|---|---|
| Light transmission | About 87%, diffuse | 85% to 90%, clear |
| Insulation | R~1.5 (twin) to R~2.1 (4-wall) | R~0.9 single pane |
| Impact / safety | ~300x glass, no shards | Shatters into shards |
| Lifespan | 7 to 20 years | 25-plus, often 40 |
| Glazing cost / sq ft | $1.60 to $3 | $2.50 to $3.50 |
What it actually costs, per square foot
Glazing chosen, the next question is the all-in number. Cost per square foot is the honest way to compare greenhouses across sizes, and it ranges widely because it bundles the frame, covering, foundation, and any heating or venting.
The working range is $5 to $35 per square foot, with most backyard builds landing in the lower half. A bare-bones plastic-film hoop sits at the bottom; a glass house with a foundation, heat, and automation sits at the top. UGA notes the structural reason the cheap end is so cheap: a plastic-covered greenhouse’s “construction cost per square foot is generally one-sixth to one-tenth the cost of glass greenhouses.” Multiply the rate by your footprint and the totals fall out: a 100 sq ft house runs about $500 to $3,500, a 200 sq ft house $1,000 to $7,000, and a 500 sq ft house $2,500 to $17,500. The lesson in those numbers is that size and glazing move the bill far more than brand does – doubling the footprint roughly doubles the cost, and stepping from film to glass can triple the per-foot rate.
| Greenhouse size | Typical total cost | Notes |
|---|---|---|
| 50 sq ft (e.g. 5×10) | $250 to $1,750 | Small kit or hoop |
| 100 sq ft (e.g. 10×10) | $500 to $3,500 | Most popular backyard size |
| 200 sq ft (e.g. 10×20) | $1,000 to $7,000 | Family-scale production |
| 500 sq ft | $2,500 to $17,500 | Approaches small-commercial |
Kit or DIY: which is actually cheaper
With a target size and budget in hand, the last fork is buy a kit or build from scratch. On raw materials DIY usually wins, but the gap is smaller than it looks once tools and rework are counted.
Take a common 10 by 6 ft footprint. Building it yourself in steel or aluminum with polycarbonate runs about $900 to $1,200, while a comparable mid-range kit in the same size falls around $1,300 to $1,700, plus $100 to $300 shipping. On paper the DIY route looks roughly $700 cheaper. The narrowing comes from what a kit bundles that a builder pays for separately: if you have to hire help or buy tools, those “DIY savings can shrink quickly,” and the biggest hidden cost is “tools and do-overs” – a miscut panel or a poorly sealed seam that leaks heat all winter. A kit ships with labeled parts and clear manuals, so the trade is money for time and certainty. DIY also wins when your site is awkward: a custom frame can step around a tree, hug a south wall, or fit a 7 ft gap that no boxed kit is sold to match.
| Path | 10×6 ft example cost | Best for |
|---|---|---|
| DIY build | $900 to $1,200 in materials | Hands-on builders with tools |
| Mid-range kit | $1,300 to $1,700 + shipping | Most buyers; speed and support |
| Premium / large kit | $3,000 to $7,000-plus | Big footprints, pro-grade frames |
Get the greenhouse parts that fit your build
Twin-wall polycarbonate panels, frame hardware, vent openers, and the bits a kit leaves out – for a build or a kit upgrade.
For most home growers the kit wins on everything but raw price: it removes the design risk, ships every part, and usually carries a warranty against UV damage and breakage. Build it yourself only if you already own the tools and enjoy the work. Either way, set the structure on a level, well-drained spot – the same siting logic that governs the raised beds you will grow in inside it.
Putting a budget together
A greenhouse budget comes together in 4 lines, and the glazing decision sets the tone for all of them. Pick polycarbonate for value and warmth or glass for looks and longevity. Size the structure and multiply by $5 to $35 per square foot – expect a 100 sq ft house around $500 to $3,500. Decide kit or DIY: a kit for speed and support at a few hundred dollars more, a DIY build to save on materials if you own the tools. Then add the hidden third – foundation, ventilation, and a permit at $100 to $600 – that the sticker leaves off. Run those 4 lines and the chaotic range collapses into a number you can plan around. When you are ready to hold heat through the cold months, the four-season design is where the glazing and insulation choices pay off.
Frequently asked questions
Is a polycarbonate or glass greenhouse better?
For most home growers, polycarbonate. Twin-wall polycarbonate costs about half what glass does per square foot ($1.60 to $3 versus $2.50 to $3.50), passes a comparable 87% of light, and insulates far better – a 4-wall panel loses heat roughly 2.3 times slower than single-pane glass, and it will not shatter. Glass wins on optical clarity and a 25-plus-year lifespan, so choose it when looks and longevity outweigh cost and the heating bill.
How much does it cost to build a greenhouse?
Roughly $5 to $35 per square foot all in, depending on glazing, frame, and finish. That puts a 100-square-foot backyard greenhouse around $500 to $3,500, a 200-square-foot house at $1,000 to $7,000, and a 500-square-foot structure at $2,500 to $17,500. A bare plastic-film hoop sits at the bottom of the range; a glass house with a foundation, heating, and automation sits at the top.
Is it cheaper to build a greenhouse or buy a kit?
Building it yourself is usually cheaper on materials – a 10-by-6-foot DIY runs about $900 to $1,200 versus $1,300 to $1,700 for a comparable kit, roughly $700 less on paper. But that gap narrows fast once you count tools, shipping, and the cost of mistakes like miscut panels or leaky seams. A kit ships every part with instructions and often a warranty, so it trades a few hundred dollars for speed and certainty.
What is a polycarbonate greenhouse kit?
A flat-pack greenhouse that ships as a frame (usually aluminum or steel) plus twin-wall polycarbonate panels, hardware, and assembly instructions. Small 6-by-8-foot kits start around $800 to $1,500, a mid-size polycarbonate-and-wood kit averages about $2,000, and large professional-grade kits run $3,000 to $7,000-plus. The polycarbonate makes them lighter, warmer, and far more impact-resistant than glass kits.
How long do polycarbonate greenhouse panels last?
Typically 7 to 20 years, depending on the grade and UV protection. Polycarbonate gradually clouds and yellows as UV exposure degrades the surface, which lowers light transmission over time, so panels are eventually replaced. Glass, by contrast, stays optically clear for 25-plus years and often 40 with maintenance – the trade for its higher cost, weight, and tendency to shatter.
What hidden costs come with a greenhouse?
Beyond the frame and glazing, budget for a foundation or level base, ventilation (automatic vent openers and an exhaust fan), and often a building permit, which typically runs $100 to $600. Heating, a watering system, and benching add more if you want year-round use. Together these routinely add 10% to 30% on top of the structure price, so factor them in before committing to a size.
References
- University of Georgia Extension. “Hobby Greenhouses” (Bulletin 910). fieldreport.caes.uga.edu
- Fixr. “Cost to Build a Greenhouse” (per-square-foot and glazing price data). fixr.com
- Backyard Discovery. “Polycarbonate Greenhouse Panels vs. Glass: The Complete Comparison.” backyarddiscovery.com
- Sunlight Gardens. “Is it Cheaper to Build a Greenhouse or Buy a Kit?” sunlightgreenhouses.com
- University of Georgia Extension. “Constructing a Passive Solar Greenhouse for Season Extension” (Bulletin 1566). fieldreport.caes.uga.edu