Class ii vapor retarder.
Polyethelene plastic sheeting 01 perms.
For instance 1 mil to 6 mil construction grade polyethylene sheeting in the construction aisle is the lowest grade of polyethylene sheeting available on the market.
A perm rating of 1 0 for any material is defined as follows.
Polyethylene plastic sheet 4 or 6 thou 0 10 or 0 15 mm 0 03 us perm 1 7 si perm.
Perm is a quantitative value that measures the relative ease with which moisture water vapor will pass through a material.
10 mil plastic.
These membranes have a permeance level that equals between 0 1 perm and 1 perm.
Construction sheeting poly america s construction sheeting is made from polyethylene which provides for optimum in economy and performance.
A true 20 mil will weigh in at about 109 msf thats about 5 pounds of plastic per mil.
It is made from up to 25 post consumer recycled goods reground resins and the absolute least expensive resins that can be bought from any source in any location across the globe.
Pure virgin polyethylene resin has nearly the same perm rating for the same thickness of plastic film from one product to another.
1 grain of water vapor will pass through 1 square foot of the material when the moisture vapor pressure difference between the colder side and the warmer side of the material is equal to 1 inch of mercury 1 in.
Because of its good weatherability chemical inertness and toughness poly america s polyethylene sheeting has successfully been used for over 20 years in a wide variety of applications.
8 mil plastic sheeting.
1 0 perm or less and greater than 0 1 perm.
Some examples to consider here are polyethylene film glass sheet metal foil faced insulated sheathing and nonperforated aluminum foil.
As such they are considered as semi impermeable products.
Plastic sheets made into tarps are available on a custom basis.
The one exception to this statement is the labor intensive process of laminating multiple layers more than 6 in a plywood style stacking to get a lower perm rating.
In the polyethylene film industry the weight is measured in pounds per 1000 square feet or msf.
Advanced polyethylene vapor retarders that pass the astm e 1745 standard tests 0 3 us perm 17 si perm.
Astm e 1745 currently specifies the maximum permeance rating of a vapor retarder to be 0 1 perms and that it be measured by either e 96 or f 1249 standard test method for water vapor transmission rate through plastic film and sheeting using a modulated infrared sensor.
The best way to identify a true thickness 20 mil vapor barrier is to look at the products weight.
3 mil plastic sheeting 6 mil plastic sheeting.
