Greenhouse: which polycarbonate thickness to choose, 4 or 6 mm?

By the AtmoSerre team

Introduction

The choice of polycarbonate thickness is one of the most important decisions for your greenhouse. Choosing a 4mm or 6mm polycarbonate sheet directly influences the protection of your plants, heat retention, and the longevity of your structure.

In this article, we will guide you to choose the best option and provide practical advice on polycarbonate sheets for greenhouses, to maximize your harvests and secure your crops all year round.

Why Polycarbonate Sheet Thickness is Essential

Not all polycarbonate sheets for greenhouses are created equal. The thickness of multiwall polycarbonate (4 mm or 6 mm) plays a decisive role in the overall performance of your garden greenhouse, whether in terms of thermal insulation, weather resistance, durability, or protection of your crops under glass.

Choosing the right thickness is not just a matter of budget: it is a strategic choice to optimize your harvests and secure your plants all year round.

🌡️ Thermal insulation: a key factor for your crops

One of the main advantages of double-wall polycarbonate is its thermal insulation capacity. The thicker the sheet, the more heat it retains during the day.

• A 4 mm polycarbonate sheet already offers good insulation for a seasonal greenhouse or use in spring and summer.

• A 6 mm polycarbonate sheet significantly improves heat retention, which is crucial for winter crops, early seedlings, or year-round greenhouse use.

Thanks to better insulation, you:

• Reduce heat loss at night.

• Limit the need for auxiliary heating.

• Maintain a stable microclimate favorable to photosynthesis and consistent plant growth.

For polycarbonate garden greenhouses, the 6 mm thickness is therefore a real asset in cold regions or those exposed to temperature variations.

💨 Weather resistance: wind, snow, and hail

The thickness of the sheets directly influences the mechanical resistance of your greenhouse. A thicker sheet is:

• More resistant to strong winds and gusts.

• Stronger against winter snowfall.

• More robust against hail impacts or minor shocks.

A 6 mm polycarbonate greenhouse is particularly recommended in windy or mountainous areas, where the structure must withstand more demanding climatic conditions.

The 4 mm remains effective for a small garden greenhouse installed in a mild climate region, but the 6 mm offers an additional safety margin to durably protect your crops.

🛡️ Durability and longevity of the greenhouse

The thickness of the polycarbonate also influences the lifespan of your greenhouse.

• 4 mm polycarbonate is lightweight, easy to handle, and perfectly suited for auxiliary greenhouses or seasonal use.

• 6 mm polycarbonate, being more rigid and thicker, limits the risk of deformation over time and better resists thermal stresses (expansion due to temperature variations).

By choosing a 6 mm double-wall garden greenhouse, you are investing in a more durable structure, designed for intensive and prolonged use, year after year.

💡 Important tip:
If you only use your greenhouse in spring and summer, a 4 mm polycarbonate sheet may be sufficient. However, for a permanent greenhouse, winter crops, or if you live in a cold or windy region, 6 mm is highly recommended to ensure better thermal insulation, increased weather resistance, and optimal longevity of your installation.

In summary, polycarbonate thickness is a central element in the performance of a polycarbonate garden greenhouse. It directly impacts the protection of your plants, the stability of the internal microclimate, and the success of your crops all year round. 🌱

4 mm vs 6 mm: advantages and disadvantages

Detailed analysis: which thickness to choose for your greenhouse?

🔹 4 mm: simplicity and efficiency for seasonal use

4 mm polycarbonate is particularly suitable for small to medium-sized garden greenhouses used from spring to autumn.

It offers effective protection against rain, moderate wind, and temperature variations while remaining economical.

It is an excellent option for:

• early seedlings,

• summer crops (tomatoes, cucumbers, herbs),

• a greenhouse project in a temperate climate region.

Its main asset remains its quality-price ratio and ease of installation.

🔹 6 mm: thermal performance and durability

6 mm polycarbonate is designed for more demanding and prolonged use.

Thanks to its greater thickness, it better retains the heat accumulated during the day, which:

• limits sudden temperature drops at night,

• protects sensitive crops in winter,

• reduces the need for supplementary heating.

It is particularly recommended for:

• a greenhouse used all year round,

• regions exposed to wind or snowfall,

• gardeners seeking a durable and high-performing installation.

✅ Expert advice

• 🌿 Seasonal use + mild climate → 4 mm sufficient

• ❄️ Annual use + cold or windy climate → 6 mm recommended

Investing in the appropriate thickness means securing your crops, optimizing your harvests, and extending the lifespan of your greenhouse.

The importance of double-wall: a decisive factor for your greenhouse's performance

Beyond the simple choice between 4 mm and 6 mm, one criterion is absolutely essential: the double-wall structure of polycarbonate.

Unlike a single sheet, multiwall polycarbonate consists of two walls connected by internal cells forming insulating air chambers. This design is not insignificant: it literally transforms the thermal and mechanical performance of your greenhouse.

🌡️ Naturally enhanced thermal insulation

The internal cells create an insulating air layer between the two walls.
Air is one of the best natural insulators.

Result:

• The heat accumulated during the day is better retained at night.

• Temperature variations are buffered.

• The internal microclimate remains more stable.

This thermal stability is crucial for:

• early seedlings,

• sensitive young plants,

• winter crops,

• reducing supplementary heating needs.

Even in 4 mm, a double-wall sheet already offers better performance than a single-layer panel.

💧 Significant reduction in condensation

Condensation is one of the most common problems in greenhouses.
A sudden difference between indoor and outdoor temperatures causes droplet formation.

Thanks to its multiwall structure, the double wall:

• limits thermal shocks,

• reduces excessive condensation formation,

• prevents direct runoff onto plants.

Less condensation means:

• fewer fungal diseases,

• healthier foliage,

• a more controlled environment.

It's a technical detail… but a real agronomic advantage.

☀️ Homogeneous light diffusion

Unlike glass or simple materials, twin-wall polycarbonate diffuses light instead of letting it pass directly and aggressively.

It ensures even light distribution inside the greenhouse, which:

• reduces shade areas,

• limits leaf burn,

• promotes more consistent photosynthesis.

Your plants thus benefit from balanced light, essential for harmonious growth.

💨 Improved structural resistance

The twin wall does not only play a thermal role.
It also reinforces the overall rigidity of the panel.

This means:

• better resistance to gusts,

• increased resistance to shocks,

• less deformation over time.

Combined with a quality aluminum structure, it guarantees a more stable and durable greenhouse.

A high-performance greenhouse is not just about thickness

We often focus on the choice between 4 mm and 6 mm, but the essential is elsewhere:

✔️ twin-wall
✔️ anti-UV treatment
✔️ assembly quality
✔️ structural rigidity

A well-designed greenhouse relies on a coherent set of materials and finishes, not just on the panel thickness.

By choosing a greenhouse equipped with twin-wall polycarbonate panels, you opt for:

• better crop protection,

• optimized thermal performance,

• superior durability,

• a more stable microclimate all year round.

And it is precisely this stability that makes the difference between a temporary greenhouse... and a truly productive and efficient greenhouse. 🌱

👉 Our polycarbonate garden greenhouses are all equipped with high-quality twin walls and are available in 4 mm and 6 mm, to adapt to both seasonal projects and permanent installations.

Thus, you choose not only an appropriate thickness, but also a structure designed to last and optimize your harvests year after year. 🌱

Installation and maintenance of polycarbonate panels for greenhouses

For your polycarbonate panels for greenhouses to last long and remain effective:

1. Installation

   • Follow the manufacturer's instructions according to the chosen thickness.

   • Ensure good overlapping of panels to prevent air or water infiltration.

   • Avoid mechanical stress: polycarbonate expands with heat.

2. Maintenance

   • Clean the panels regularly to maximize light.

   • Check fasteners and seals, especially after winter.

   • Avoid abrasive products to prevent scratching or weakening the polycarbonate.

FAQ on polycarbonate panels for greenhouses

1. Question: Can 4mm and 6mm be mixed on the same greenhouse?
   Answer: In theory, it is possible to mix 4mm and 6mm, but we recommend choosing a single thickness for the entire greenhouse. This helps avoid temperature variations inside and ensures uniform thermal insulation for all your crops.
2. Question: Do polycarbonate panels for greenhouses resist snow?
   Answer: 4mm panels already resist snow very well, but 6mm panels offer even more robust protection and are recommended for cold or winter regions, where snowfall can be significant.
3. Question: What is the lifespan of a polycarbonate panel for a greenhouse?
   Answer: On average, 4mm lasts 10-12 years, 6mm can exceed 15 years if well maintained.

Conclusion: 4mm or 6mm, a strategic choice for your crops

The choice between 4mm and 6mm polycarbonate should not be limited to a question of price. It primarily depends on your climate, your frequency of use, and your growing ambitions.

• 🌿 For seasonal use in temperate regions, 4mm offers an excellent compromise between lightness, efficiency, and controlled budget.

• ❄️ For a greenhouse used year-round, exposed to cold, wind, or snow, 6mm provides reinforced insulation, better thermal stability, and superior durability.

Beyond thickness, the quality of the twin wall, the robustness of the structure, and the overall design of the greenhouse play a decisive role in its actual performance.

A well-chosen greenhouse, adapted to your environment and objectives, becomes a true controlled production space. It protects your plants, secures your harvests, and allows you to cultivate with serenity season after season.

Ultimately, investing in the appropriate thickness is investing in the stability of the microclimate... and in the lasting success of your vegetable garden. 🌱