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"Visqueen" Vapor Barrier  as a Vapor Retarder

Posted by The Plastic Sheeting Gurus! on Wed, Jul 06, 2016 @ 04:49

 

So often people are looking for a  "Visqueen" vapor barrier.  What they are really asking for is some sort of plastic sheeting to use as a vapor barrier/retarder to slow water from coming up through the slab. The term "Visqueen" is actually a brand of plastic sheeting just like "Kleenex" is a brand of tissue. People will ask for a "Kleenex" when really they want a tissue. The same goes for "Visqueen".  It is a brand. 

Why are vapor barriers used under concrete you ask...Moisture that is in the ground slowly rises to the surface. This is problematic if you are putting tile or carpeting on top of the concrete in the way of flooring.  Vapor barriers AKA vapor retarders are a sheet of plastic that blocks the water from reaching the concrete slab. The key to selecting a vapor barrier is understanding the function of a well made vapor barrier. A vapor barrier designed specifically to slow moisture or act as a barrier from water rising up has to meet the ASTM E 1745 "Standard Specification for Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill Under Concrete Slabs"  testing specifications. This test measures how pourous the plastic sheeting/ vapor barrier material is.  "Visqueen" type plastic as of this writing has not been tested to the specs that insure you can depend on the vapor barrier to slow water transmission.

Vapor barrier for concrete

"Visqueen" is also referred to as a "Construction and Agricultural" film C&A film.  It may contain up to 25% post consumer recycled content, and is made from the least expensive resins available at any given time. While it is excellent for use in many projects, it is not ideal for any use that requires sustained strength such as a tarp or for use as a vapor/moisture barrier or retarder. People will often do a search for "visqueen vapor retarder", or fire retardant visqueen" when they may be looking for an engineered plastic. An engineered plastic is one that is intentionally designed to meet certain measurable criteria to insure its suitability for the job it is intended for. 

When looking for a vapor retarder/barrier, we recommend  an engineered film. C&A films often completely breaks down within a couple of years. Have you ever dug up some old black plastic? Remember how torn and crusty it was? It's important that today's vapor/moisture barriers or retarders should pass the ASTM E 96 Class A, B and C (standard for under-slab vapor retarders in contact with soil or granular fill).  ASTM E 96 measures in part the "permeance" or how much water can pass through the vapor barrier.  You need a liner that is 0.3 perms or less. In terms of thickness, 10 mils and above will offer much better protection and resistance to moisture transmission.   If you need to over-lap the vapor retarder, 6 inches at the seams, taped and sealed around column and the like.

The bottom line is doing your due diligence regarding vapor barriers and selecting one that is not a "visqueen vapor barrier" and go with  liner that is engineered and tested to do the best job for the application. The last thing you want is to notice your carpeting is moist, or the laminent is coming un-glued from the floor!

Tags: film

The History of Polyethylene

Posted by Nana Hinsley on Fri, Feb 13, 2015 @ 10:19

On March 27, 1933, two organic chemists working for the Imperial Chemical Industries Research Laboratory were testing various chemicals. To  R.O Gibson and E.W. Fawcett's surprise the white, waxy substance they were testing would become a revolutionary substance that would change the world. Polyethylene was born!

 polethylene resin for plastic sheeting

The researchers set off a reaction between ethylene and benzaldehyde, in an autoclave. It seems their testing container sprang a leak and all of the pressure escaped. There was the white, waxy substance that greatly resembled plastic. Upon carefully repeating and analyzing the experiment, the scientists discovered that the loss of pressure was only partly due to a leak; the major reason was the polymerization process that had occurred leaving behind polyethylene. The first patents for polythene were registered in 1936 by Imperial Chemical Industries.  A year later the first practical use for the material, as a film, was discovered. In 1953 Karl Ziegler of the Kaiser Wilhelm Institute and Erhard Holzkamp invented HDPE (High Density Polyethylene). From there, two years later, in 1955, HDPE was produced as pipe.  Ziegler was awarded the 1963 Nobel Prize for Chemistry.

Did you know that polyethylene played a key supporting role during World War II? It was first  used as an underwater cable coating and then as a critical insulating material for  vital military applications as radar insulation. This is because it was so light and thin that it made placing radar onto airplanes possible thus vastly reducing the weigh. The substance was a highly guarded secret.

After the war, polyethylene became a tremendous hit with consumers It became the first plastic in the United States to sell more than a billion pounds a year. It is currently the largest volume plastic in the world.

 Today, Polyethylene has the advantages of excellent moisture-vapor, chemical, and electrical resistance. It is widely used for making containers, wire cable insulation, pipe, linings, coatings, and engineered films. It is used to power transmission, consumer goods, packaging, electronics household good and more. Its principal disadvantage is poor mechanical strength, unless it has a little help from scrim reinforcement! Developments in technology continues to improve its functionality making it the most efficient use of natural resources petroleum and natural gas. We applaud these scientists for creating polyethylene that is used in a variety of plastic sheeting products today.

Polyethylene is the largest volume polymer produced globally, with over 90 million metric tons per year!


Tags: plastic sheeting, polyethylene, film, history of polyethylene