Information You Have To Be Informed About Concrete Vapor Barrier

· 3 min read
Information You Have To Be Informed About Concrete Vapor Barrier




What is a concrete vapor barrier?
A concrete vapor barrier is any material that prevents moisture from entering a concrete slab. Vapor barriers are utilized because while fresh concrete is poured wet, it’s not supposed to stay doing this. It needs to dry and then stay dry to avoid flooring problems.




If you’ve ever endured a problem with a basement floor (or any concrete floor), you understand the type of damage this too much moisture may cause. Moisture enters concrete in a number of ways, including via the ground, from humidity via a flight, via leaky plumbing that passes through a slab. Needless to say, there’s even the moisture that was from the original concrete mixture.

There’s only one-way moisture leaves concrete, though, and that’s via its surface. When you have a concrete floor that’s in continuous exposure to a source of moisture, you’re gonna have problems. For this reason a vapor barrier under concrete is vital. Vapor barriers are a good way to maintain moisture from getting yourself into the concrete.

Note: A vapor barrier isn't identical to an underlayment. However, you can find underlayments that act as vapor barriers.

Vapor barrier permeability is expressed in perms.
Vapor barriers have varying numbers of permeability, expressed in perms. The greater the number, the harder permeable the information. Impermeable vapor barriers are those with a rating of 0.1 perm or less while class II vapor retarders are the types which has a rating higher than 0.1 perm much less than 1.0 perm.

You’ll hear people while using terms ‘vapor barrier’ and ‘vapor retarder’ interchangeably. However, strictly speaking, they aren’t the same thing. Vapor barriers are less permeable than vapor retarders. In the following paragraphs, i will be with all the term ‘vapor barrier’.

Exactly why is excessive moisture in concrete a challenge?
One word: adhesives. An excessive amount of moisture in concrete is a dilemma given it might cause pH changes that destroy adhesives. Here’s what happens.

As moisture makes its approach to the counter of the concrete slab, soluble alkalies come along for your ride and lift its surface pH above those of flooring adhesives. This will cause the adhesives to breakdown and you end up having flooring failures like swelling, bulging, or cupping.

Do you need a vapor barrier with a concrete slab?
In a word, yes. Here’s why.

There’s more often than not water underneath a structure site. It may not be close to the surface, but that doesn’t mean it’s not there. This water can progress over the soil and come into experience of the bottom of a concrete floor via capillary action. Capillary action could be stopped by installing something called a capillary break, a layer of crushed rock which goes between the subgrade along with the slab.

Capillary breaks do a passable job of stopping water rolling around in its liquid state from reaching a slab. However, they can’t stop water in vapor form from reaching and entering a layer of concrete. Therefore, there must be something underneath the slab that prevents vapor moisture from entering.

You might also need a vapor barrier for liability reasons since most manufacturers of flooring include vapor barriers or retarders inside their installation guidelines.

How thick should a plastic vapor barrier be?
According to the Self-help guide to Concrete Floor and Slab Construction published by the American Concrete Institute, a vapor retarder mustn't be under 10 mils thick. You will need a much thicker barrier though if you’re covering material with sharp angles.

Net profit: Vapor barriers have to be sufficiently strong enough enough so that they don’t easily puncture. Whenever they do, moisture can get in and that’s what you’re always keeping out.


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