The Arcadia lean-to greenhouse is a Belgian-made glass greenhouse that attaches to a wall of your house, garage or shed. It comes in six standard sizes, from a slim 5' deep model for side yards to a 10' x 15' garden room. It is a beautiful, solid choice for small lots, but it is an advanced build that needs a good wall and a careful installer.
We sell and support the Arcadia, and this guide covers what the product page can't. You will learn which size fits, what your wall needs, and how much heat a lean-to really saves.
✅ Quick answer
- What it is: a glass lean-to greenhouse with 4mm tempered glass, a black aluminum frame and rubber glazing seals.
- Sizes: Arcadia 5x13 and 5x15, plus Arcadia Plus 8x10, 8x15, 10x10 and 10x15.
- Vents: 2 roof windows on every size, one with an automatic opener. Plus models add a louvered window.
- Not included: wall-mounting hardware and the weather stripping that seals the gap to your wall.
- Build: plan on a contractor or very skilled handyman, about 2 to 3 days.
What is the Arcadia lean-to greenhouse?
A lean-to greenhouse has three glass sides and a sloped roof. The fourth side is an existing wall. The Arcadia is part of the Janssens Helios line and shares the essential design of the Royal Victorian, in a half-house shape.
It is built from 17-gauge tubular aluminum with a black (RAL 9005) finish. The vertical glass is a single, full-height pane, not two overlapping pieces that trap dirt. Gutters and downspouts are included.
Here is what every Arcadia shares, according to the manufacturer's specs:
- Glazing: 4mm tempered safety glass held in rubber seals instead of metal clips.
- Roof vents: two roof windows, one with a manual opener and one with an automatic opener.
- Testing: TUV and GS tested and approved.
- Made in: Belgium.
Want the basics on lean-tos in general first? Read what a lean-to greenhouse is and why you may need one.
What sizes does the Arcadia lean-to come in?
There are two families. The standard Arcadia is about 5' deep for narrow spaces. The Arcadia Plus is 7'6" to 10' deep, with heavier roof framing and longer roof glass.
| Model | Exact size | Floor area | Door and extra vents | Price guide* |
|---|---|---|---|---|
| Arcadia 5x13 | 5'2" x 12'7" | ~65 sq ft | Single sliding; 2 push-out windows | ~$9,799 |
| Arcadia 5x15 | 5'2" x 15' | ~78 sq ft | Single sliding; 2 push-out windows | ~$10,999 |
| Arcadia Plus 8x10 | 7'6" x 10'2" | ~76 sq ft | Single sliding; 1 louver | ~$12,999 |
| Arcadia Plus 8x15 | 7'7" x 15' | ~114 sq ft | Single sliding; 1 louver; 2 push-out | ~$14,999 |
| Arcadia Plus 10x10 | 10' x 10'2" | ~102 sq ft | Double sliding; 1 louver | ~$10,999 (in-stock unit ~$7,849) |
| Arcadia Plus 10x15 | 10' x 15' | ~150 sq ft | Double hinged; 1 louver; 2 push-out | ~$18,499 |
*Prices checked in November 2026. Prices can change and sales may apply, so click the model name to see today's price. Floor areas are worked out from the exact sizes. Every size also has the 2 roof windows.
Peak heights run from 9'2" on the 5' models to 10'4" on the Plus 10x15. Side walls are about 6'7" to 6'8" tall on every size.
📌 Lead times: some Arcadia sizes are in stock. Others are built as a special order at the Janssens factory in Belgium, so they take longer. Call us to check before you plan your build date.
Arcadia or Arcadia Plus: which should you choose?
The choice usually comes down to how deep your space is, and how you want to use it.
🌿 Choose the standard Arcadia if:
- You have a narrow side yard, patio or walkway.
- You want a long shelf of herbs, seedlings and pots along one wall.
- You want the simpler delivery. Only the Plus requires a flatbed and forklift.
🏡 Choose the Arcadia Plus if:
- You want benches on both sides, or a chair and a small table.
- You want a louvered window for low airflow.
- You want heavier 17-gauge profiles in the gutter, rafters, ridge beam and gable bar.
⚠️ Delivery for the Plus: the Arcadia Plus needs a flatbed and forklift to unload, which you arrange. Without one, you need at least four people to unload the glass panels one by one.
Is a lean-to better than a freestanding greenhouse?
It depends on your yard. A lean-to trades some light for convenience, warmth and space. Here is how the two compare.
| Factor | Lean-to (Arcadia) | Freestanding |
|---|---|---|
| Yard space | Uses a wall you already have | Needs open ground plus walking room |
| Heat loss | Lower: the back wall isn't glass | Higher: glass on all sides |
| Light | From three sides and the roof | From every side |
| Access | Steps from the house; easy water and power | A walk across the yard |
| Install | Wall sealing and flashing needed | Foundation only |
General comparison. Your wall, orientation and climate make the biggest difference.
How much heat does a lean-to greenhouse save?
A greenhouse loses most of its heat through the glass. A lean-to has no glass on the back wall, so it has less glass to lose heat through. Here is a simple way to see the difference.
🧮 Formula: heat loss
Heat loss (BTU per hour) = glass area (sq ft) x U-value x temperature difference (°F)
For single-pane glass, a common rule of thumb is a U-value of about 1.1.
Worked example: Arcadia Plus 10x15. It is 10' deep and 15' long, with a 6'7" front wall and a 10'4" peak at the house wall.
- Roof: the slope is about 10.7' long, so 10.7 x 15 = about 160 sq ft.
- Front wall: 15 x 6.6 = about 99 sq ft.
- Two end walls: each is 10' wide, averaging about 8.5' tall, so about 169 sq ft together.
- Total glass: about 428 sq ft.
- To keep it 40°F inside on a 10°F night (a 30°F difference): 428 x 1.1 x 30 = about 14,100 BTU per hour.
If the back wall were glass too, it would add about 155 sq ft. The same night would then need about 19,200 BTU per hour. So the house wall cuts the heat loss by roughly a quarter. A warm masonry wall can also give back some heat at night.
These are estimates for sizing, not exact numbers. Try your own climate in our greenhouse heater calculator, or see real costs in how much it costs to heat a greenhouse in winter.
Which wall should a lean-to greenhouse face?
In the US, a south-facing wall gets the most winter sun, so it is the first choice for year-round growing. Here is how the other directions compare:
- East: gentle morning sun. A good second choice, and cooler in summer.
- West: strong afternoon sun. It can overheat in summer, so plan for shading and good airflow.
- North: little direct sun. Best for shade plants or overwintering, not for fruiting crops.
💡 Sun check: stand at the wall at noon in winter, when the sun is lowest. Note any trees, roof overhangs or neighbors' buildings that cast shade. Winter shade matters most for a year-round greenhouse.
What does your wall need before you order?
The wall is half of your greenhouse, so check it first. The product page lists what is not included: hardware for attaching to the building, and weather stripping to seal the gap.
- Height: the peak meets the wall at 9'2" to 10'4", depending on size. Leave room below eaves, gutters and windows.
- Strength: brick, block, stone or a framed wall with solid backing works best. Your installer picks the right fasteners.
- Openings: plan around dryer vents, outlets, hose bibs and doors.
- Water: make sure rain drains away from the house. Have the joint to the wall flashed and sealed.
- Permits: an attached structure often needs a permit. Ask your building office early.
Because the Arcadia is so customizable, the manufacturer can't provide structural certifications. We can put you in touch with the engineering firm that did ours.
What foundation does the Arcadia need?
The Arcadia uses the same base approach as the Royal Victorian. The manual recommends an 8" wide concrete strip foundation that goes down to your frost line. Corner brackets on the base frame reach 12" below ground.
- Leave a 4" hole at each corner so the anchors can be set in concrete.
- Set the anchors only after the frame is built and confirmed level and square.
- Going on a knee wall? The manual notes a hinged door can be easier to work with.
A foundation drawing for the Arcadia is linked on the product page. For step-by-step help, our Royal Victorian foundation, anchoring and flooring guide covers the same methods.
How hard is the Arcadia to install?
This is not a weekend kit. The product page calls the Arcadia and Arcadia Plus advanced builds for a contractor or highly skilled handyman.
- Heavy roof glass: the roof panels are very large and heavy. Extra scaffolding may be needed.
- Time: about 2 to 3 days, depending on the crew.
- Wall work: fastening and sealing to the building is part of the job.
- Tools: the manual lists a metric tape, a 10mm socket, a level, a drill, an impact driver and a stable 6' ladder.
We are not affiliated with any crew, but our Assembly Crews page lists independent installers. Email us and we will share names other customers have used.
What can you grow in an Arcadia lean-to?
With tall side walls and a high back wall, a lean-to is great for growing up as well as out. Our customers often use theirs for:
- Herbs and greens: basil, lettuce and kale on shelves along the glass.
- Seed starting: trays of spring seedlings, steps from the kitchen door.
- Tall crops: tomatoes or cucumbers trained up the back wall.
- Overwintering: potted citrus, geraniums and tender perennials.
💡 Winter care: the glass is single pane, so expect some condensation inside. Clear snow from the roof. The manual also suggests bracing the ridge beam with a 2x4 at the center if heavy snow is coming.
What does the Arcadia cost, and what else should you budget?
When we wrote this in November 2026, the Arcadia ranged from about $9,799 for the 5x13 to about $18,499 for the Plus 10x15. Shipping is free to the continental US by curbside freight. Also plan for:
- A concrete strip foundation.
- Wall-mounting hardware, flashing and weather stripping.
- Professional installation and any permit fees.
- A heater, shelving and shading, if you want them.
📌 About prices: manufacturers update their prices during the year, and we often run sales and promotions. The price on the product page is always the current one. Prices in this article are a guide from when we wrote it (November 2026), not a quote or guarantee. Found a lower price for the same model at an authorized retailer? We offer a Price Match Guarantee - please check the rules first. Call us and we will confirm today's price and any current deals.
Need a size or color that isn't listed? Custom Arcadia models are available through our custom greenhouses page. For a bigger glass room against the house, also look at the Hoklartherm Berlin Solarveranda.
Frequently asked questions
Can I attach a lean-to greenhouse to my house?
Yes. That is what the Arcadia is designed for. It can attach to a house, garage, shed or other building. The mounting hardware and weather stripping are not included, so your installer supplies them.
What is the difference between the Arcadia and Arcadia Plus?
The Plus is deeper, from 7'6" to 10'. It has heavier roof framing, longer roof glass and a louvered window. It also needs a flatbed and forklift to unload.
Do I need a permit for a lean-to greenhouse?
Often, yes, because it attaches to a building. Rules vary by town, so ask your building office before you order. The manufacturer can't certify custom Arcadia setups, but we can connect you with an engineering firm.
Is a lean-to greenhouse warmer than a freestanding one?
Usually, yes. The back wall isn't glass, so less heat escapes. In our example, the Arcadia Plus 10x15 loses roughly a quarter less heat than it would with a glass back wall.
What warranty does the Arcadia have?
The Janssens warranty covers the aluminum frame and stainless hardware for up to 15 years, and other defects for up to 10 years. Tempered glass, opener pistons and snow damage are not covered.
Can I install the Arcadia myself?
Only if you are a very skilled builder. The roof glass is large and heavy, and the wall connection must be sealed well. Most customers hire a contractor or an experienced crew.
Thinking about an Arcadia lean-to?
We are a small, woman-owned business in Georgia, and we answer every question personally. Send us a photo of your wall, its direction and its height. We will help you pick the right size, check stock and lead times, and find an assembly crew. Shipping is free to the continental US.
