Basement Vapor Barrier: Yes or No?

Basement vapor barrier, yes, or no? It’s a question that homeowners have asked for decades. Every homeowner wants their house to be a safe, happy place for themselves and their family. One way to ensure that is by properly maintaining your home’s insulation. 

When it comes to basement insulation, there are two main options: installing a vapor barrier or not installing one at all. In this article, we’ll explore the pros and cons of each option so you can make an informed decision on which route is best for you and your home!

What is a Basement Vapor Barrier?

A vapor barrier in a home is a material that prevents moisture from entering or exiting through your basement walls. The most common vapor barrier types are plastic sheeting and polyethylene film, which you can easily purchase at hardware stores.

How Does It Work?

The purpose of a basement insulation system is to reduce moisture levels within the walls and floors of the basement. Walls are made of cement, which is porous. This means that moisture can quickly move through the walls, leading to mold and mildew growth.

A vapor barrier will prevent this by creating a physical barrier between the wall and the environment.

Classification of Vapor Barriers

Vapor barriers are classified into three classes depending on permeability. Class I vapor barriers are the best at preventing moisture from entering or exiting walls, but they also cost more than Class II and III. 

Class I

A Class I vapor barrier typically has a permeability of 0.1 perms. This type of barrier is impermeable to water vapor and is the most effective at preventing moisture from entering or exiting walls. They include the following materials;

  • Polyethylene sheet
  • Sheet metal
  • Rubber membrane

Class II

A Class II vapor barrier typically has a permeability greater than 0.01 perms. This class is semi-permeable, meaning it is not entirely impermeable to water vapor. These include the following materials;

  • Bitumen coated Kraft paper
  • Thirty-pound asphalt coated paper
  • Unfaced expanded polystyrene

Class III

A Class III vapor barrier has a permeability of greater than 1.0 perms and is considered permeable to water vapor. Materials that fall into this category are typically less expensive but don’t provide the same level of protection as a Class I barrier. 

Materials that can act as a Class III vapor barrier include;

Fiberglass insulation with kraft paper facing.

Gypsum board.

Board lumber.

Fiberglass insulation (unfaced).

Cellulose insulation.

House wrap

Basement Vapor Barrier Yes or No

Having a basement barrier is extremely important and should be a significant focus during the construction of any new home. The vapor barrier will not only reduce moisture levels that can lead to mold, but it will also protect your belongings from water damage and keep you safe by reducing carbon monoxide emissions.

Benefits of having basement vapor barrier in your home

Below are some of the benefits of having a basement vapor barrier:

  • It prevents moisture from entering and exiting the walls, leading to mold and mildew growth. The Growth of mold and mildew can cause a health hazard for your family. If left to grow unchecked, mold can cause respiratory problems. 
  • Basements are often used as living spaces, which means that you and your family are constantly exposed to carbon monoxide emissions. These emissions can cause severe health problems over time if left untreated.
  • The basement vapor barrier prevents water damage to belongings and the basement itself. Water damage can be a costly issue to repair. A vapor barrier will protect your belongings and the structure of your home from water damage.
  • Basement can have less musty odors due to a reduction in humidity levels. Most smells are caused by excess moisture that enters through the floor or wall cracks and travels into the air within your home.
  • Easy to Install. Vapor barriers are easy to install and can be done by the homeowner. With the correct tools and skillset, you can install your basement barrier within a few hours.
  • Saves on energy cost; the barrier will reduce the amount of moisture in your home, making it easier for your heater to warm up and maintain a comfortable temperature.
  • Increases the lifespan of the pipes; moisture leads to corrosion and rusting, which can lead to your pipes breaking, leaking, or bursting.

Cons of having basement vapor barrier in your home

Below are some disadvantages to installing a basement vapor barrier:

1. Installation cost.

 Although installing a vapor barrier is cheaper than repairing the damage from mold and mildew growth, it can still be expensive. Depending on the size of your basement, you may need to purchase additional materials or have multiple barriers installed for it to work correctly.

In addition, barrier clogs easily with hair and dirt particles which will cause water leaks over time. Not a big deal if you have a sump pump, but it cannot be easy to cleanout.

2. Only one option for basement insulation. 

If you choose not to install a vapor barrier in your home, the only other option is to allow moisture into your basement and flooring with no protection whatsoever! 

3. Requires experts for installation

It can be challenging for unskilled homeowners to properly install the vapor barriers without getting them wrong, which will lead to further problems down the road. If you do not know what you’re doing, it’s best to hire a professional.

4. Increased humidity

Vapor barriers can trap moisture within your basement walls, leading to increased humidity levels and poor air quality. A buildup of condensation on the exterior side of the vapor barrier can cause musty smells similar to those caused by high humidity levels in general. For this not to happen, you can wall mount the best dehumidifier to control the humidity levels within your home.

5. Prone to damage

Some vapor barriers are susceptible to damage during installation; if the barrier is punctured during installation, the barrier can negate its ability to protect you. Once this happens, you will need to cover the barrier with a secondary layer of protection, adding up to the cost.

6. Most installations are limited to new buildings

If your home is already built, you will not be able to install a vapor barrier without tearing down walls and doing some extensive reworking.

  1. Basement Vapor Barrier; No

Choosing not to install a vapor barrier in your home is choosing to do nothing about the moisture problems in your basement. Failure to install a vapor barrier comes with more discomforts and higher expenses than having a barrier installed in the first place.

Cons related to not having basement vapor barrier in your home

  • House smells musty; there is nothing worse than living with a home that has an unpleasant odor! You can expect to have your basement smell like mildew by not installing a vapor barrier within months after moving in. This will be particularly noticeable during the warmer months of summer.
  • Water damage; moisture and humidity levels will increase over time, leading to water damage. Water damage is one of the leading causes of mold growth within homes. Without a barrier, you’re putting your health at risk as well as endangering those living in your home.
  • Increased moisture; Health problems such as asthma attacks or allergies that often affect people with respiratory issues like bronchitis can worsen with excessive moisture in the air. These health problems are usually caused by high humidity levels and improper air ventilation.
  • Pipe corrosion and rusting; water leads to corrosion and rusting, which can lead to your pipes breaking, leaking, or bursting. This will cause extensive damage not only to the pipes but also to your floors and walls.
  • High energy consumption; if the humidity levels in your home are too high, your air conditioning unit will need to work overtime to try and combat the extra moisture in the air. This will lead to an increase in your energy consumption bill each month.
  • Damage to basement foundation; over time, the water that leaks in and accumulates on your basement floor will cause damage to the foundation of your home. This can be a costly repair that will require professional help.


Basement Vapor Barrier; Yes!

Installing a vapor barrier is the best way to protect your basement from moisture and humidity damage. By choosing not to install a vapor barrier, you decide to do nothing about the problem and risk extensive damage that will be costly to repair. As mentioned above, there are many benefits of installing a vapor barrier in your basement.


When building a new home, installing a vapor barrier should be at the top of your list. If you already live in a home and have moisture problems in your basement, installing a vapor barrier is not too late. It may require some demolition work, but it is well worth the time and money!

Installing a vapor barrier comes with many benefits mentioned in detail above. By not installing a vapor barrier, you risk extensive damage to your home that will be costly to repair.

Every homeowner needs to protect their home from moisture and humidity damage. The best way to do that is by installing a basement vapor barrier!