What is a concrete vapor barrier?

A concrete vapor barrier is any material that forestalls moisture from entering a layer of concrete. Vapor barriers are employed because while fresh concrete is poured wet, it’s not meant to stay this way. It has 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 know the sort of damage that as well much moisture can cause. Moisture enters concrete in several ways, including using the ground, from humidity in the air, and thru leaky plumbing that goes through a slab. Needless to say, there’s the moisture which was within the original concrete mixture.

There’s only one-way moisture leaves concrete, though, and that’s via its surface. In case you have a concrete floor that’s in continuous connection with a source of moisture, you’re planning to have problems. That is why a vapor barrier under concrete is important. Vapor barriers are a great way to maintain moisture from stepping into the concrete.

Note: A vapor barrier is not the same as an underlayment. However, there are underlayments that work as vapor barriers.

Vapor barrier permeability is expressed in perms.

Vapor barriers have varying levels of permeability, expressed in perms. The higher the number, the more permeable the material. Impermeable vapor barriers are the type which has a rating of 0.1 perm or less while class II vapor retarders are the ones using a rating greater than 0.1 perm and much less than 1.0 perm.

You’ll hear people while using the terms ‘vapor barrier’ and ‘vapor retarder’ interchangeably. However, as it happens, they aren’t a similar thing. Vapor barriers are less permeable than vapor retarders. On this page, we are using the term ‘vapor barrier’.

How come excessive moisture in concrete a difficulty?

A word: adhesives. An excessive amount of moisture in concrete is a problem because it might cause pH changes that destroy adhesives. Here’s what are the results.

As moisture makes its way to the counter of the concrete slab, soluble alkalies appear to the ride and lift its surface pH above that relating to flooring adhesives. This leads to the adhesives to breakdown and also you end up having flooring failures for example swelling, bulging, or cupping.

Do you need a vapor barrier with a layer of concrete?

In short, yes. Here’s why.

There’s more often than not water underneath a building site. It might not be near the surface, but that doesn’t mean it’s not there. This water can progress up through the soil and are available into exposure to the foot of a concrete floor via capillary action. Capillary action can be stopped by installing something referred to as a capillary break, a layer of crushed rock that goes involving the subgrade along with the slab.

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

There is also a vapor barrier for liability reasons since the majority manufacturers of flooring include vapor barriers or retarders in their installation guidelines.

How thick should a plastic vapor barrier be?

Based on the Guide to Concrete Floor and Slab Construction created by the American Concrete Institute, a vapor retarder shouldn’t be below 10 mils thick. You will need a level thicker barrier though if you’re covering material with sharp angles.

Important thing: Vapor barriers must be sufficiently strong enough so they don’t easily puncture. If they do, moisture will get in and that’s what you’re always keeping out.

To read more about nilon lot san be tong have a look at the best webpage