Greenhouse plastic film: galgas, microns and which one to choose

In Spain, greenhouse film thickness is expressed in galgas, which equal microns multiplied by 4: 800 galgas are 200 microns, the usual thickness of a greenhouse cover. Besides thickness, look at whether it is thermal (it retains more heat at night), its colour and the warranty in months. In winter a thin second-roof film of 100 to 150 galgas is added under the cover.

What are galgas and how do they convert to microns?

The galga is a commercial convention of the Spanish market, not an SI unit: the thickness in microns multiplied by 4. So 800 galgas = 200 microns, 150 galgas ≈ 38 microns and 100 galgas = 25 microns. In other countries the same film is sold directly in microns: a 200-micron film is an 800-galga film.

Cover film: thermal or non-thermal

Cover film protects the greenhouse and also influences the light, temperature and humidity the crop receives. These are the Grupo Criado y López cover references:

Source: Criado y López cover film datasheet (November 2026). Depending on the type, the film includes properties such as thermal effect or anti-drip.

How to read the table: at the same thickness, what changes is the thermal effect (how much heat it retains at night) and the warranty. If the crop spends cold nights under cover, a thermal film is worth considering; we help you choose according to the area and the growing cycle.

Second roof: the thin winter film

The second-roof film is a thin plastic installed under the cover, mainly in winter, to retain heat during the night. It also protects the cover from the chemicals applied inside the greenhouse.

• 120-150 galgas (30-38 microns), natural, thermal or non-thermal, anti-fog; single use.
• 100 galgas (25 microns), natural, high-transparency thermal and anti-fog (Powerlux); single use.

And the vents?

The film closes the roof; the roof and side vents are protected with insect netting so the greenhouse ventilates without letting pests in. We explain it in Anti-thrips netting 10x16, 10x20 or 13x31: which to choose.

Who supplies it

Cover film and second-roof film are made by Grupo Criado y López, which Novafrut is part of, in El Ejido (Almería). Ask us for a quote with the greenhouse dimensions, the area and the crop, and we will recommend the right reference.