What Is 6 Mil Plastic Sheeting Made Of? | Material Facts

6 mil plastic sheeting is made of polyethylene, most commonly low-density polyethylene (LDPE), though some products use recycled or reinforced polyethylene.

Whether you’re laying a vapor barrier in a crawl space or protecting materials from weather, knowing what 6 mil plastic sheeting is made of matters more than you’d think. The short answer is polyethylene, but the details vary by product. Some rolls are plain LDPE, others are recycled polyethylene, and a few are reinforced with a scrim layer for extra strength. That difference affects durability, permeability, and where you can safely use it.

The Core Material: Low-Density Polyethylene

The most common material in 6 mil plastic sheeting is low-density polyethylene, or LDPE. This is the same flexible plastic family used in grocery bags, shrink wrap, and squeeze bottles, but in sheet form it’s extruded to a controlled thickness. Clear poly sheeting marketed for construction is explicitly labeled as LDPE and meets ASTM D2103, a standard covering polyethylene film for general-purpose use.

LDPE is popular for this application because it’s cheap to produce, flexible enough to drape over irregular surfaces, and resistant to water, chemicals, and tearing under normal conditions. It’s also lightweight relative to its strength, which makes large rolls manageable for one person to handle.

Not All 6 Mil Sheeting Is the Same

Just because two rolls both say “6 mil” doesn’t mean they perform identically. Here’s what differs between products on the market:

• Standard LDPE film — the most common type; inexpensive and adequate for short-term moisture control.
• Recycled polyethylene — several 10 x 100 ft. and 10 x 50 ft. construction-grade rolls are made largely from recycled material; they work fine for most jobs but can be less consistent in appearance.
• Reinforced polyethylene — Pro Line Products makes a version with an extrusion-laminated scrim layer embedded in the film, giving it noticeably higher tear resistance for demanding applications.

Reinforced sheeting costs more, but the added strength is worth the difference when you’re covering sharp edges or rough surfaces that would puncture standard film.

If you’re weighing options for an upcoming project, our roundup of the best 6 mil plastic sheeting picks compares top-rated rolls for different budgets.

Thickness and Performance Limits

Six mil equals 0.006 inches, which puts this sheeting in the medium-duty range. It’s heavier than the 1–2 mil films used for painting drop cloths, but thinner than the 10–20 mil films used for heavy pond liners and industrial containment.

The standard references for 6 mil polyethylene film are ASTM D2103 and ASTM D4397, which cover polyethylene sheeting used in construction, industrial, and agricultural settings. Pro Line Products lists these along with A-A-3174 for its construction-grade rolls.

What 6 Mil Plastic Sheeting Is (and Isn’t) For

6 mil plastic sheeting is built for construction and utility work, not food storage. Common uses include vapor barriers under concrete slabs, crawl space moisture barriers, temporary weather protection, drop cloths, and weed control under mulch or gravel.

Three limitations matter for most buyers. First, standard 6 mil is not UV treated, so Pro Line’s 6 mil poly construction sheeting data sheet confirms prolonged outdoor exposure will break it down. Second, it is not flame retardant and should never be used near ignition sources. Third, despite what the name suggests, it’s not truly impermeable — one product’s data sheet lists an average water vapor transmission rate of 0.13 perms, meaning moisture can slowly pass through over time.

For interior moisture control, that permeability is usually fine. For food-contact surfaces or long-term outdoor use, you need a different material entirely.