When selecting plastic sheeting for construction, gardening, or protective projects, thickness is a primary specification. The term “mil” is often confused with the metric unit “millimeter,” leading to misunderstandings about the material’s actual durability. Accurate measurement is necessary because the thickness of the plastic directly determines its strength, puncture resistance, and suitability for applications like vapor barriers or heavy-duty ground cover.
Understanding the Mil Unit
The unit known as a “mil” is a measurement of length within the imperial system, specifically used to describe the thickness of thin materials like plastic film, wire, and coatings. A single mil is precisely defined as one-thousandth of an inch, or 0.001 inches. This unit has been standardized in the manufacturing world, particularly in the United States, for its convenience in specifying material tolerances with high precision.
It is easy to see why the name creates confusion, as a millimeter is also a common unit of thickness, but the two are vastly different in scale. One millimeter is approximately 39.37 mils, meaning a millimeter is nearly 40 times thicker than a single mil. For perspective, a typical human hair strand measures between 2 and 5 mils in diameter. The mil unit provides a fine-grained scale for distinguishing between light-duty and much heavier-duty sheeting.
The Conversion: 6 Mil to Millimeters
Six mil plastic sheeting is 0.1524 millimeters thick. This numerical conversion is derived by applying the internationally recognized conversion factor between the imperial and metric systems. Since one mil equals 0.001 inches, and one inch is equivalent to exactly 25.4 millimeters, the calculation is straightforward.
The formula involves multiplying the mil thickness by the metric conversion factor for a single mil (0.0254 millimeters). Therefore, 6 mils multiplied by 0.0254 millimeters per mil results in the precise thickness of 0.1524 millimeters. This precision is fundamental for ensuring compliance in building codes and engineering specifications.
Common Uses for 6 Mil Plastic Sheeting
The 6 mil thickness is a standard for many heavy-duty applications, balancing durability and flexibility. In residential and commercial construction, 6 mil polyethylene sheeting is frequently used as a vapor barrier beneath concrete slabs or within wall assemblies. Building codes often specify this thickness as the minimum requirement for preventing moisture intrusion from the soil or ambient air.
The material’s enhanced puncture resistance makes it suitable for use as a temporary cover on construction sites to protect equipment and materials from adverse weather. Its ability to withstand moderate wear and tear also makes it a popular choice for heavy-duty drop cloths during painting and renovation projects.
Beyond construction, 6 mil sheeting is widely employed in agricultural settings, particularly for greenhouse coverings, providing durability against wind and hail. When formulated with ultraviolet (UV) inhibitors, the plastic maintains its physical properties despite continuous sun exposure. This thickness is also utilized for lining trenches, creating temporary containment zones, and serving as a robust ground cover in landscaping.