Riga 4 Greenhouse Kit | 135 sq. ft.

What's Included?

Every Riga 4 Greenhouse Kit ships as a complete kit:

• All polycarbonate panels (8mm sides, 10mm gable ends)
• Complete aluminum frame with all extrusions and connectors
• Barn-style hinged door with upgraded handle and key lock (30" W x 79" H)
• 2 roof ventilation windows with automatic openers
• 1 large rear wall window
• Heavy-duty rubber seals throughout
• All hardware and fasteners
• Detailed assembly guide

Ships in 3 boxes. Free curbside delivery to the lower 48. The carrier will call to schedule your delivery appointment.

Important delivery note: The Riga 4 ships via freight on an 18-wheeler truck. Please ensure the delivery truck can access your property before ordering. If access is limited, contact us before placing your order and we'll discuss options.

Why Buy from South Table Sheds

We're an authorized Exaco dealer based in Golden, Colorado, with 17 years of experience with outdoor structures. When you buy from us, you're not just dealing with an online store, you're working with people who've assembled these greenhouses, know how they perform through Colorado winters, and are available to answer real questions before and after your purchase.

• Free shipping to the continental US
• Secure checkout with Shop Pay installments available
• Authorized Exaco retailer, purchase fully protected
• Professional assembly available across the Denver metro
• Call us directly: 720-656-7313

The Riga 4 — The Dedicated Grower's Greenhouse

The Riga 4 is where gardeners land when they're ready to start growing.  At 135 square feet 9'8" wide by 14' long and 7'7" at the peak,  this is a greenhouse with real working space. Two full growing benches with a generous center aisle, enough floor space for raised beds and containers, and two automatic roof vents that keep temperatures consistent across the full length of the structure.

The 9'8" width gives you 2 full feet more interior space than the S series, and that extra width changes how the space works. You can run wider benches, move around more freely, and bring in larger plants without maneuvering around tight corners. The taller 79" door makes that even easier.

This is the greenhouse dedicated growers across Colorado buy when they're done compromising on space. If you're growing vegetables year-round through a Front Range winter, starting hundreds of seedlings, or overwintering a serious collection of plants, the Riga 4 gives you the room to do it right.

Denver Area? Add Professional Assembly

South Table Sheds has been building and assembling outdoor structures across Colorado since 2008. If you'd rather spend your time growing than reading instruction manuals, we'll handle the entire assembly — from site prep through final inspection.

Get a free assembly quote →

Assembly available throughout the Denver metro, Golden, Boulder, Lakewood, Arvada, Littleton, Centennial, Aurora, and surrounding Front Range communities.

Why Choose the Riga 4 Greenhouse Kit?

The Riga 4 greenhouse is designed around one principle: the minimum insulation needed to grow plants year-round without excessive heating costs. Here's what that means in practice.

Most budget greenhouse kits use 4–6mm single-wall polycarbonate panels. A single-wall panel has no insulating air gap.  Heat escapes as fast as it's generated, and heating costs reflect that. The Riga 4 uses 8mm twin-wall panels on the side walls and 10mm twin-wall on the gable ends. The air gap between the two walls creates an insulating barrier that retains heat significantly longer than single-wall alternatives.

For Colorado gardeners running a heater through our cold nights, this difference shows up in your energy bill every month from October through April. The Riga 4 costs more upfront than a budget kit, and costs less to operate every year you own it.

Beyond insulation, the Riga 4 is engineered for the conditions that matter most on the Front Range:

• Hail resistance  twin-wall panels absorb impact rather than shattering
• Wind performance aerodynamic curved roof redirects wind rather than catching it
• Snow shedding curved profile sheds snow naturally rather than accumulating loads
• UV protection  10-year panel warranty against UV degradation at altitude
• Frame longevity  13-gauge anodized aluminum with 15-year warranty

Riga 4 vs. Riga 3 - What's the Difference?

Both are Large series greenhouses sharing the same 9'8" width and 7'7" peak height. The difference is length, growing area, and number of roof vents:

The Riga 4 costs $1,200 more than the Riga 3 and gives you 33 additional square feet, 3.5 more feet of length, and a second automatic roof vent. For dedicated growers who want maximum working space in the Large series, the Riga 4 is the natural step up.

Why the Riga 4 Outperforms Every Other Greenhouse in Its Class

8mm + 10mm Twin-Wall Polycarbonate: Not All Panels Are Equal

The Riga 4 uses 8mm twin-wall polycarbonate on the side walls and 10mm panels on the gable ends. Most competing greenhouses use uniform 4–6mm single-wall panels throughout. The difference in heat retention, hail resistance, and UV protection is significant, especially at Colorado's elevation where UV intensity is considerably higher than at sea level.

Aerodynamic Curved Roof: Engineered for Snow Country

The distinctive bell-shaped curved roof isn't just a design choice,  it's engineering. Snow slides off rather than accumulating into dangerous loads. Wind rolls over rather than pushing against flat surfaces. This matters everywhere, but especially on the Front Range where March can deliver 2 feet of wet spring snow overnight.

Two Automatic Roof Vents: Consistent Temperature Control

At 14' long, two automatic roof vents are essential for even temperature distribution. Both vents respond to temperature independently,  no electricity required. Combined with the large rear wall window and the tall 79" barn-style door, cross-ventilation across the full length of the Riga 4 is excellent even during Colorado's most intense summer afternoons.

Taller Dutch Door with Upgraded Handle

The Riga 4's door stands 79" tall with an upgraded handle. Moving large plants in and out is significantly easier, and the upgraded hardware is more durable for daily use over many seasons.

13-Gauge Aluminum Frame:  Built to Last Decades

Every extrusion is substantial anodized aluminum, not the thin-wall tubing found in budget structures. Hoklartherm backs the frame with a 15-year warranty. The polycarbonate panels carry a 10-year warranty against UV degradation. This is the kind of structure you're still using when your kids are grown.

Precision German Manufacturing

Hoklartherm has been building greenhouses in Germany for over 30 years. Every hole lines up. Every panel fits. Every connector seats properly. The unique channel design of the aluminum components allows for simple slide-and-fit assembly, saving time and reducing the frustration common with lesser-made kits.

Optional Add-Ons

Foundation Frame (+$1,499) The aluminum foundation frame provides a level perimeter base when mounting to a prepared surface. Buries in a shallow trench around the perimeter for a solid, level anchor. Strongly recommended for Colorado's freeze-thaw soil conditions.

Shelf System Purpose-built shelving that hangs from the frame rather than the walls, preserving floor space and light penetration:

• Top Shelf — 10" wide x 13'10" long (+$439)
• Bottom Shelf — 25" wide x 13'10" long (+$624)

The suspended shelf system is one of the Riga 4's most distinctive features. It adds usable growing space without compromising structural integrity or blocking light.

The Riga Large Series:  Find Your Size

• Riga 3 — 102 sq. ft. (9'8" x 10'6") — The entry point. Perfect balance of space and footprint. $6,899
• Riga 4 — 135 sq. ft. (9'8" x 14') — You are here. Two automatic roof vents, serious working space.
• Riga 5 — 165 sq. ft. (9'8" x 17'6") — Maximum Large series space, four automatic roof vents. $9,199

Looking for a narrower footprint? The Riga S series starts at 54 sq. ft. with a 7'8" width, from $5,999.

Need a professional-grade structure? The Riga XL 6 steps up to 14' wide with 16mm triple-wall glazing.

Resources and Manuals

Download the Riga 4 Assembly Guide (PDF)

Watch the Riga Assembly Video on YouTube

Frequently Asked Questions

How does the Riga 4 hold up in Colorado hailstorms?

Better than most greenhouse kits on the market. The Riga 4 uses 10mm twin-wall polycarbonate on the gable ends and 8mm twin-wall on the side walls, both significantly thicker than the 4–6mm single-wall panels found on budget greenhouses. The twin-wall construction absorbs impact rather than shattering, and the polycarbonate itself is far more impact-resistant than glass. Colorado's Front Range sees some of the most intense hail in the country, and the Riga 4's panel thickness and curved roof profile,  which deflects rather than catches impact, making it one of the better-suited greenhouse kits for our climate.

How wind-resistant is the Riga 4?

The Riga 4's aerodynamic bell-shaped curved roof is specifically engineered to perform in high-wind conditions. Rather than presenting flat surfaces for wind to push against, the curved profile redirects airflow up and over the structure. Customers in high-wind regions,  including the Sierra Nevada, coastal New England, and the Great Plains,  regularly report the Riga holding up through extreme wind events. On Colorado's Front Range, where chinook winds can gust well above 60 mph along the foothills, the Riga 4's frame and panel system is engineered to handle the load. For maximum wind resistance, we recommend anchoring to a solid foundation,  either a concrete pad or the optional aluminum foundation frame.

How much does it cost to heat a Riga 4 greenhouse in Colorado?

Significantly less than heating a single-wall greenhouse of the same size. The 8mm and 10mm twin-wall polycarbonate panels create an insulating air barrier that retains heat much longer than single-wall alternatives. Most Colorado gardeners maintain above-freezing temps overnight with a small 1,500-watt electric heater or a compact propane unit. Running costs depend on your target temperature and how cold it gets,  but the Riga 4's insulation advantage is meaningful from October through April on the Front Range.

What foundation does the Riga 4 need?

Three solid options: a concrete pad for maximum permanence, a level bed of compacted gravel or pavers for drainage and accessibility, or the optional aluminum foundation frame directly in soil. For a structure this size, a concrete pad or the foundation frame is strongly recommended for long-term stability in Colorado's freeze-thaw soil conditions.

Do I need a building permit in Colorado for a greenhouse this size?

At 135 square feet, the Riga 4 may fall close to or above permit exemption thresholds in some Front Range municipalities. Rules vary significantly by city and HOA,  Jefferson County, Arapahoe County, Denver, and surrounding cities each have their own thresholds. We've navigated these requirements for 17 years. For a full overview, see our guide on Colorado building permits for sheds, greenhouses, and saunas.

What's the difference between the Riga 4 and Riga 4s?

The Riga 4s is 7'8" wide with a 72" door. The Riga 4 is 9'8" wide with a 79" door and upgraded handle. Both are 14' long with 2 automatic roof vents. The Riga 4 gives you significantly more interior width, better headroom, and a taller door, a meaningful upgrade for gardeners who want maximum working space.

Does South Table Sheds offer greenhouse assembly services?

Yes. Our team offers professional greenhouse assembly throughout the Denver metro and Front Range. Contact us for a quote — we're typically booked 2–4 weeks out during peak season, so reach out early.

What's the advantage of two roof vents over one?

On a 14' long greenhouse, a single roof vent concentrated at one end creates uneven temperature distribution. Two vents positioned along the length allow heat to escape more evenly, keeping temperatures consistent across the full growing space. On Colorado's intense summer afternoons this makes a real difference in plant health.