Greenhouse Film Specs Explained: UVI, IR/AC, Thickness & Warranty

Feb 1st 2026

Greenhouse film labels can look like a string of abbreviations that only make sense to manufacturers. UVI. IR/AC. 6 mil. 4-year. Anti-drip. Diffusion. Warranty terms. The problem is that each of those specs affects crop performance, heating costs, condensation behavior, and how long your cover actually lasts.

This article explains what the common greenhouse film specs mean, why they matter, and how to choose the right combination for your structure and growing goals.

Start here: how to read a greenhouse film label

Most greenhouse poly film “codes” are trying to tell you four things:

  1. How long the film is expected to resist UV breakdown (UVI and the year rating)
  2. Whether the film is designed to reduce night heat loss (IR)
  3. Whether the film is designed to control condensation behavior (AC, anti-drip, anti-fog)
  4. The film’s thickness and build (mil, layers, reinforced, diffusion)

A few examples of what you might see printed on a roll:

  • 6 mil, 4-year, UVI, IR/AC
    Typical greenhouse-grade film with UV stabilizers, infrared heat retention, and anti-condensation surface treatment.
  • 6 mil, 1-year, UVI, no IR/AC
    A short-term film, often used for seasonal tunnels or overwintering where you plan to replace it soon.
  • 9 mil or 12 mil, reinforced, condensation control, longer life
    A heavier-duty option aimed at tougher weather, longer service life, and fewer puncture failures.

If you know what each part means, you can match a film to a real problem you are trying to solve, instead of buying based on price alone.

UVI explained: what “UV inhibitors” actually do

UVI generally refers to UV inhibitors or UV stabilizers added during manufacturing. Polyethylene film breaks down under sunlight over time. UV stabilizers slow that process, which is why greenhouse-grade film lasts years while cheap plastic can fail quickly.

What UVI does for you in practical terms

When the film is UV-stabilized:

  • It stays flexible longer instead of turning brittle
  • It resists cracking and premature tearing from normal temperature cycling
  • It maintains usable light transmission longer before yellowing and haze reduce performance

HALS and other stabilizers: why some films last longer than others

Many long-life greenhouse films use stabilizer systems such as HALS (hindered amine light stabilizers). You do not need to memorize the chemistry to benefit from it. What matters is that higher-quality stabilizer packages typically mean better long-term durability under sun exposure.

Why UVI “years” is not a universal number

A “4-year” UVI rating is not a guarantee that every greenhouse in every climate will get four perfect years. Sun intensity, elevation, and exposure conditions vary. Chemical exposure also matters. Some pesticides, disinfectants, and fumes can accelerate degradation. If your greenhouse environment includes high chemical use or you run sulfur burners, your film choice needs to account for that.

What to ask before you buy

If you are choosing film based on UVI, ask for:

  • The UV rating in years and what the manufacturer considers “normal” exposure
  • Whether the film is intended for single layer or double layer inflated systems
  • Any chemical sensitivity warnings that could apply to your operation

IR explained: how “thermal” films reduce night heat loss

In greenhouse film specs, IR usually refers to an additive designed to reduce radiant heat loss at night. Even if your structure is well sealed, clear polyethylene can still allow infrared radiation to escape. IR-treated film helps hold more of that heat inside.

When IR film makes a noticeable difference

IR film is most valuable when:

  • You heat the greenhouse and fuel cost matters
  • Nights are cold and skies are clear, which increases radiative heat loss
  • You want more stable night temperatures for crop quality and timing

Many growers describe it as a film that helps the greenhouse “coast” longer at night, reducing heater run time and smoothing temperature drops.

Where IR film belongs in a double layer inflated system

If you run double poly, IR film is typically used as the inner layer so it can reflect long-wave radiation back into the greenhouse. This is one of those details that affects performance more than people expect.

What IR does not do

IR is not a substitute for:

  • Double-layer inflation
  • Tight end walls and good sealing
  • Proper heater sizing
  • Ventilation strategy

It is a film feature that can support an energy plan, not replace one.

AC explained: anti-condensate, anti-drip, and why it matters for crops

Condensation is not just annoying. It affects light, humidity, and disease pressure. When warm, humid interior air contacts a colder film surface, moisture condenses. Standard film tends to form droplets that hang, merge, and drip.

Anti-condensate treatments change the surface behavior of water so it sheets into a thin layer and runs off instead of forming large droplets.

What anti-drip changes inside the greenhouse

When anti-condensate works as intended, you usually see:

  • Less random dripping onto foliage and blooms
  • Fewer “lens” droplets that can concentrate light and create hot spots
  • Cleaner film appearance and more consistent light distribution through the day

It does not eliminate humidity. It changes the way water behaves once it condenses.

Why anti-condensate is especially valuable in certain houses

AC film tends to matter most when:

  • You have high plant transpiration and frequent condensation cycles
  • Nights are cold, and mornings warm quickly
  • Ventilation is limited during certain seasons
  • You grow crops sensitive to leaf wetness and drip injury

A detail many people miss: drainage path

Anti-drip works best when water has a path to move down the film and off into gutters or edges. If the film is sagging, poorly tensioned, or installed with low spots, water can still pool.

Thickness: 4 mil, 6 mil, 9 mil, 12 mil and what “stronger” really means

Thickness is easy to compare, so people fixate on it. Thickness matters, but it is not the only driver of lifespan.

Why 6 mil is the common baseline

6 mil greenhouse film is widely used because it balances:

  • Strength and handling
  • Flexibility in temperature swings
  • Compatibility with most common greenhouse attachment systems
  • Cost relative to expected service life

It is often paired with a multi-year UV rating and optional additives like IR and AC.

When thicker film is the smart move

Stepping up to thicker or reinforced options can make sense when you deal with:

  • High wind exposure and repeated flap damage
  • Abrasion risk from frame contact or netting
  • Hail events that would shred standard film
  • Longer planned service life where change-outs are disruptive

Reinforced film is a different category

Reinforced greenhouse plastic is not just “thicker poly.” Reinforced films are designed to resist catastrophic tearing when punctured. For growers who have dealt with one small hole turning into a long rip overnight, reinforced film is often about risk reduction as much as lifespan.

The practical tradeoff

As thickness increases:

  • Handling and installation can require more care
  • Cost increases
  • The right attachment and tensioning become even more important

If the structure has sharp edges or corrosion points, thicker film will still fail. The film is only as safe as the surface it touches.

Warranty explained: what is usually covered, and what is usually excluded

Film warranties can be misunderstood because the word “warranty” feels like full coverage. In reality, greenhouse film warranties are commonly focused on UV degradation and manufacturing defects. Many things growers experience as “failure” are excluded.

What many warranties cover

Common coverage areas include:

  • Premature UV degradation, often defined by a measurable loss of tensile strength
  • Manufacturing defects such as splits on folds or incorrect roll dimensions
  • A defined exposure period tied to the film’s rated life

Some warranties are prorated or offered as a discount on replacement film instead of a refund.

What many warranties exclude

Common exclusions often include:

  • Wind, hail, snow, or extreme weather damage
  • Mechanical damage from puncture, abrasion, or sharp frame contact
  • Improper installation or single-layer use when the film is designed for double-layer
  • Chemical contamination or exposure beyond specified limits
  • Overheating from heaters or hot air directed at the film
  • Contact with certain materials or accessories that accelerate degradation

This is why “how you install and operate” is part of the film decision. A film may be rated for multiple years, but your greenhouse environment can shorten that life if certain conditions are present.

How to protect your warranty claim, if you ever need it

Most manufacturers want the same documentation:

  • The full printed code on the film
  • Delivery date and install date
  • A description of the structure and installation method
  • Chemical usage details and frequency
  • Photos and a sample from the affected area

If you keep those records from day one, you are in a better position if you ever need support.

Putting it together: choosing film specs by your growing situation

Instead of trying to chase the “best” film, choose the film that addresses your limiting factor.

If your main problem is heating cost and cold nights

Start with:

  • Double-layer inflated setup
  • IR-treated inner layer
  • UVI rating that matches your replacement schedule
  • Condensation control if drip and leaf wetness are recurring issues

This combination targets fuel use and night temperature stability first, then solves the moisture behavior that often comes with heated houses.

If your main problem is condensation drip and humidity swings

Prioritize:

  • Anti-condensate (AC) or dedicated condensation control film
  • Good tension and proper drainage to avoid pooling
  • Ventilation strategy that prevents chronic leaf wetness cycles

In many houses, film choice improves condensation behavior, but airflow and temperature management determine whether humidity stays in the safe zone.

If your main problem is wind damage and puncture failures

Look at:

  • Better tensioning and attachment method first
  • Thicker or reinforced film if failures continue
  • Higher durability film options when replacement downtime is expensive

When wind damage is the driver, installation quality often produces the biggest improvement. Film upgrades are the second step, not the first.

If your greenhouse is seasonal and you replace film often

A short-term UVI-rated film can be a smart choice when:

  • You truly plan to replace it within a season or year
  • You want the lowest cost option that still performs predictably
  • IR features would not pay back because you are not heating much

Pro-Tect greenhouse film options you can match to these specs

If you want to map these specs to real products, here are examples available through Pro-Tect Plastics:

If you are not sure which combination fits your crop and structure, the fastest path is to decide what problem you are solving first, then choose specs that target that problem without creating a new one.

FAQs

Does IR film reduce light transmission?

Some reduction can happen with any added layer or treatment, especially in double-layer systems. The tradeoff is often worthwhile in heated houses where energy savings and warmer night tissue temperature support crop performance. If you rely on winter light to drive production, treat light as a spec you confirm, not an assumption.

Does anti-condensate treatment wear out?

Anti-drip performance can change over time due to environmental conditions and film aging. Proper ventilation, correct tension, and keeping the film clean can help the film perform closer to how it was designed.

Should IR film be on the inside or outside layer in double poly?

IR film is typically used as the inner layer in a double-layer inflated system so it can reduce radiative heat loss from the interior environment.

What does “4-year UVI” really mean?

It is usually a UV resistance rating tied to defined exposure conditions and warranty terms. Real-world life depends on sun intensity, installation quality, chemical exposure, weather events, and the condition of the structure.

What can shorten greenhouse film life the fastest?

Chemical exposure and mechanical stress are two major causes. Corrosion points, sharp edges, flapping from poor tension, and certain chemicals or fumes can all accelerate degradation even when the film is technically rated for multiple years.