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What are the Best Polycarbonate Greenhouse Kits?

Mont Polycarbonate Greenhouse

Polycarbonate greenhouse kits are extremely popular.  Many people prefer polycarbonate greenhouse kits because of the favorable light transmission, strong insulation, lightweight durable design, and shatter resistant profile of the material.  

This article will explain why polycarbonate greenhouse kits are popular and highlight the best options currently available on the market. 

Polycarbonate Greenhouse Pros 

  • Polycarbonate panels are stronger and weigh less than glass panels.
  • Shatter resistant yet flexible and easy to work with.
  • Protective against UV solar radiation.
  • Favorable light transmission
  • Energy cost savings compared with glass panels.
  • Multi Wall design offers significant insulation benefits. 

Polycarbonate Greenhouse Cons

  • Polycarbonate panels have a higher relative cost compared with other material.
  • Requires additional cleaning to maintain the appearance.
  • Slightly less light transmission than glass.

Polycarbonate Heat Retention in Greenhouses 

The relative value of building insulation is determined by calculating an R-Value and a U-Factor which evaluates a material’s relative resistance to heat transfer.  

  • R-Value is a calculated value of heat retention.
  • U-Factor is a calculated value of heat loss. 

When evaluating the insulation of greenhouse material, you want to look for lower U-values and higher R-values. 

  • A higher R-value indicates better heat retention.
  • A lower U-value indicates lower heat loss.

Benefits of Twin Walled Polycarbonate 

Twin wall Polycarbonate offers significant improvements in greenhouse insulation compared with single wall polycarbonate and single pane glass.

A twin wall design increases insulation by increasing the density of the surface through which heat must transfer to exit the greenhouse.  

Insulation Values of Polycarbonate

  • Corrugated Polycarbonate: R-Value: .88 / U-value: 1.14
  • 3mm Single Pane Glass: R-Value: .95 / U-Value: 1.05
  • 4mm Twin Wall Polycarbonate: R-value: 1.54 / U-Value: .70
  • 8mm Twin Wall Polycarbonate: R-Value: 1.60 / U-Value: .63

As highlighted by the insulation values, 8mm twin wall polycarbonate offers a substantial improvement in overall insulation ability compared with glass and single wall corrugated polycarbonate.

Light Transmission

Light transmission represents the quantity of light passing through the greenhouse window panels. Depending on the material, the light can fully pass through the greenhouse panel or light can be partially absorbed or fully reflected. 

Light transmission is reflected as a percentage.  100% represents full transmission and any percentage less than 100% represents partial light transmission. 

  • Single pane of glass light transmission: 95%
  • Polycarbonate 6mm twin wall light transmission: 82%
  • Single wall polycarbonate light transmission: 76%

In terms of light diffusion, clear and white colored panels provide more light diffusion whereas darker colors provide less light diffusion. 


If you live in a climate with harsh winter weather, it is very important to select a greenhouse kit that can withstand heavy snow and wind.  Durability is evaluated based on the strength of the greenhouse’s frame. 

Greenhouse kits with high rated snow load capacity and high rated wind load capacity are key indicators of the ability of a greenhouse to hold up in challenging winter conditions. 

Snow load is measured in pounds per square foot and wind load is measured in miles per hour.

Polycarbonate based greenhouse kits perform very well in harsh winter conditions.  The flexible and shatter resistant profile of the window panels performs very well in strong winds and heavy snow fall. 

Additionally, the high R-Values and low U-Values of twin wall polycarbonate provides substantial insulation benefits in cold weather climates. 

Site Preparation & Assembly

All outdoor greenhouse kits require adequate space and flat leveled ground. 

  • The greenhouse can be placed on a lawn, bare ground, a gravel base, over a wood deck, a concrete slab, or a brick patio.
  • We recommend using a gravel base with smaller to mid-sized greenhouse kits.
  • Cover the compacted gravel with landscape fabric. The key is to have a water permeable surface so that water can drain from the greenhouse floor.
  • Larger sized greenhouse kits work best with a more sturdy and permanent foundation like concrete or brick.
  • Make sure the ground is flat and level before starting assembly.

Expect to spend a full weekend assembling the greenhouse.  Ideally two or more people will be available to help with the setup.  

If you are not comfortable with basic assembly, we recommend contacting a local contractor or handyman service to help with the assembly.

Top Polycarbonate Greenhouse Kits

We evaluated polycarbonate greenhouse kits on the basis of visual appeal, value, insulation rating, and durability.

Mont Greenhouse

Mont Greenhouse 

  • Click Here to Purchase Mont Greenhouse Base Model

The Mont Greenhouse is a commercial grade greenhouse that is designed for both new and experienced gardener’s. The greenhouse is designed with high quality extruded aluminum and 8mm twin wall polycarbonate. 

This means the Mont Greenhouse provides substantial insulation benefits (1.60 R-Value & .63 U-Value) which is almost double the insulation values provided by single pane glass and single wall polycarbonate greenhouse glazing.

The Mont Greenhouse is available in five primary sizes:

  • 8 feet long x 8 feet wide x 7.8 feet high
  • 8 feet long x 12 feet wide x 7.8 feet high
  • 8 feet long x 16 feet wide x 7.8 feet high
  • 8 feet long x 20 feet wide x 7.8 feet high
  • 8 feet long x 24 feet wide x 7.8 feet high
  • Click here to see all Available Mont Greenhouse Sizes 

You also have a choice of getting a base level package or a premium package.  The premium package includes the following additional accessories: 

  • Commercial work bench
  • Interior Shade system
  • Programmable watering system
  • Greenhouse sink system

Additional Benefits of the Mont Greenhouse include:

  • Large lockable double door included
  • Expandable in 4 foot increments if you run out of space.
  • Snow load capacity of 24 pounds per square foot
  • Wind load capacity of 65 miles per hour.
  • 10 year warranty
  • Estimated average annual energy cost of $125 to $175 with incremental energy cost increases of approx. $25 to $50 with the largest sizes models.

Best Polycarbonate Greenhouse for Hot Climates

Mont Mojave

Mont Mojave

The Mont Mojave is also designed with an extremely durable polycarbonate glazing, but also includes a full solar ventilation system with tinted roof and ventilation panels.

  • Click Here to See all Available Sizes of the Mont Mojave

Greenhouses located in areas with very high temperatures will benefit from reduced energy costs with the solar panels. 

The Mojave is designed with the same high quality aluminum frame and polycarbonate glazing included with the base Mont model, but also includes the following: 

  • Solar Ventilation system
  • Commercial bench system
  • Tinted roof and ventilation panels
  • Programmable watering system
  • Greenhouse sink
  • Vegi-bee mechanical pollinator system