Thickness is the easiest number to compare, so it is the one most buyers focus on. It is also the one most likely to be misunderstood.
A thicker cover is not automatically a longer-lasting one. Answering how thick should plastic be for a greenhouse means knowing what thickness actually controls, and what it has almost nothing to do with.
Mil and Micron Measure the Same Thing
Two systems are in circulation and they cause regular confusion.
Mil is a thousandth of an inch, used mainly in the United States. Micron is a thousandth of a millimetre, used almost everywhere else.
The conversion is straightforward: one mil equals roughly 25 micron.
That gives the common sizes in both systems. Four mil is about 100 micron, six mil about 150 micron, and eight mil about 200 micron.
So a listing for 6 mil greenhouse plastic uv resistant film and one for 150 micron UV-stabilised film describe the same thickness in different units. Worth knowing before you pay extra for what you already have, and worth confirming which unit a quote uses. Urban Plastic can confirm the equivalent figure for any thickness you are comparing.
Why 6 Mil Became the Standard
Six mil, or around 150 micron, is the most widely used greenhouse covering thickness, and that is not an accident.
It sits at the point where the film is strong enough to survive being stretched over a frame, handle normal wind loading, and resist the occasional knock, while staying light enough for two people to manage a large sheet and cheap enough to cover a big area.
Thinner films save money but tear more readily during installation, which is when most damage happens. Thicker films handle abuse better but become heavy, stiff, and awkward to pull tight over curved hoops.
For most production greenhouses, this is the sensible starting point, and you move away from it only for a specific reason.
What Thickness Actually Controls
- Tear and puncture resistance. This is the main thing. A thicker film survives a dropped tool, a branch blown against it, or a careless step on the frame.
- Wind performance. Film in wind flexes constantly. Thicker material tolerates that flexing longer before failing at the fixing points.
- Handling during installation. Thicker film resists being nicked on frame edges and bolt heads while being pulled into place.
- Tear propagation. Once a small tear starts, thicker material slows its spread, which buys time to patch before the hole becomes a tear across a whole bay.
What Thickness Does Not Control
This is where most of the money gets wasted.
Lifespan under sunlight. Thickness does almost nothing here. The additive package determines how long a film survives ultraviolet exposure. An unstabilised 8 mil film will turn brittle and yellow long before a 6 mil greenhouse plastic uv resistant film does.
Put plainly, a thicker film without proper UV protection fails just as surely as a thin one. It simply takes slightly longer to tear once it has gone brittle.
Light transmission. Thickness has only a marginal effect. Clarity, diffusion and surface condition matter far more than the extra fraction of a millimetre.
Condensation behaviour. Entirely down to anti-drip treatment, not thickness.
Heat retention. Determined by the polymer and infrared additives, not by how thick the sheet is.
When to Go Thicker Than 6 Mil
A few situations justify the extra cost and weight.
- Exposed sites with strong or gusty wind, where constant flexing shortens film life at the fixings.
- Structures with wide spans between supports, where the film carries more unsupported area.
- Houses in heavy use, where people, trolleys and equipment regularly brush against the walls.
- Long replacement cycles, where the cover will stay up as long as possible and physical damage over time is the main worry.
Note that going thicker means checking your frame. A heavier cover puts more load on hoops and fixings, and stretching stiffer film tight demands a structure that will not flex.
When Thinner Is Reasonable
- Low tunnels and small hobby structures with short spans, where wind loading on any single panel is small.
- Seasonal covers taken down after each crop and not expected to last years.
- Nursery shading and propagation areas inside a larger protected structure, where the film is already sheltered.
For anything that must stand through a full monsoon season unattended, thin film is a false economy.
Thickness Is One Number Among Several
So how thick should plastic be for a greenhouse? For most production structures, a 6 mil greenhouse plastic uv resistant film at around 150 micron, moving up to eight mil where wind, span or heavy use justify it, and down to four mil only for small sheltered or seasonal structures.
But the number on its own tells you very little. Thickness governs how well a cover survives physical stress. It says almost nothing about how long that cover survives sunlight, and sunlight is what ends the life of most greenhouse films.
So when comparing two quotes, check the thickness first to make sure the units match, then stop comparing thickness and start comparing stabiliser packages. That is where the real difference in working life sits.
For more information about Greenhouse Plastic UV please contact: Whatsapp/Mobile Phone: +62 811 1721 338 (Ms. Ais) or Email : info@urbanplastic.id