Vapor Barrier?

By Nick Rollo

If you think the terms Vapor Barrier and Vapor Retarder are the same, then you may be making the wrong product choices.

Trapped moisture is bad for buildings, we all know that. What you may not know is how permeability ratings affect a product's ability to resist diffusion of moisture through walls, ceilings, flooring, concrete slabs, beams and more. Permeability, which is the amount of moisture that can pass through a material, is measured in perms. The lower the number, the less permeable the material, and the more moisture it will block. A Vapor Barrier or Vapor Retarder is any material used for damp proofing, typically a plastic or foil sheet. A Vapor Barrier will stop all moisture and gas from passing through, whereas a Vapor Retarder will allow some moisture and gas to pass through.

There are three distinct types of Vapor Barriers and Vapor Retarders all with varying perm ratings.

Class I: Perm level of 0.1 perm or less. This is considered impermeable and is what qualifies as a Vapor Barrier.

Class II: Perm between 0.1 perm and 1 perm. This is considered semi-impermeable and is a Vapor Retarder.

Class III: Perm between 1 perm and 10 perms. This is considered semi-permeable and is a Vapor Retarder.

Class I vapor retarders are also called vapor barriers because they stop the movement of water vapor almost entirely. If the perm rating is greater than 10, it's not considered a vapor retarder. It's a permeable material.

Knowing the difference between these terms will help you make good product choices that will ultimately help protect a building from significant rotting and decay. If you want to stop moisture, you want a Vapor Barrier and a tape that meets the same standards to seal all of your seams. You’ve heard it said that “A chain is only as strong as its weakest link” but the same applies for Vapor Barriers: a barrier is only as strong as its weakest seam. Yellow Guard makes their own tape to ensure you’re compliance, but whatever brand of tape you use, make sure you’re using the appropriate vapor barrier tape or you may be creating an expense that can turn your project upside down

Yellow Guard® Vapor Barriers are offered in 10, 15 or 20 mil thickness and all have 0.1 perms or less, making them all Class I Vapor Barriers. Husky® Yellow Guard premium vapor barriers are manufactured using top-quality 100% pure polyethylene resins, and not only are they durable, puncture-resistant, and able to withstand cold temperatures but they also have perm levels that are up to 10 times lower than industry standards. Husky® Yellow Guard® is manufactured in the USA by Poly-America with state-of-the-art manufacturing. It is manufactured to be in contact with soil and even restrict the migration of soil gasses such as radon and methane.

Now that you know the definition of a Vapor Barrier and what Yellow Guard® Vapor Barriers offer, it’s clear that not only do they meet the definition of barrier but they significantly exceed it, making it the clear choice for moisture protection.