A professional laying on his chest investigates a crawl space with a flashlight

A 2014 survey by Eye On Housing confirms that about 15% of homes in the United States have crawl spaces. 

Crawl spaces are beautiful and offer some utility, but they hugely affect your energy bills. Air from outside enters the crawl space, affecting relative humidity and, in turn, heating and cooling systems. 

Encapsulating crawl spaces is not cheap, but when you think of the benefits, it’s apparent that the expenses are worth it. 

This article will explain how crawl space encapsulation reduces energy bills, its other benefits, and how to go about it. 

How Much Energy Do You Save by Encapsulating Your Crawl Space?

You can save up to 20% on your energy bills by encapsulating crawl spaces in your home. Crawl space encapsulation ensures the air in that area doesn’t seep into the main areas of the house from underneath. That way, your heating or cooling system doesn’t need to work as hard. 

How Does Crawl Space Encapsulation Work?

If your home has a crawl space, there is a high chance you have moisture problems

These challenges occur for several reasons, including:

  • Openings like doors and windows
  • Ducts pass through the crawl space
  • The space is close to the earth’s temperature

Crawl space moisture problems affect the heating and cooling systems, both running on energy. 

When the air within your home is hot, it gathers momentum and disperses into different parts of the house, but some of it escapes. The air usually escapes from the upper part of your building, causing pressure on the lower parts. 

Unlike the basement, crawl spaces have vents, so air comes in to deal with the increased pressure in that space. If you think about it, it is more like heating or cooling the home at one point, then bringing in some hot or cold air through another point. 

Encapsulating that space will completely block the areas where air is seeping into the crawl space. Depending on the professional you hire for the job, there are different materials used for crawl space encapsulation. 

However, the process of crawl space encapsulation is usually the same.

Steps for crawl space encapsulation include:

  • Inspection – the first step any encapsulation expert will take is to visit your home to inspect the crawl space. The situation of your crawl space is vital to the decisions they make on your encapsulation. 
  • Interior cleaning – crawl spaces are usually dirty, and with mold growing, it will become worse. The expert needs to have the area cleaned to make more informed decisions. Messy crawl spaces usually have a lot of blind seepage spots. 
An immaculate crawl space in a home
  • Exterior cleaning – dirt and other contaminants on the outside of the space may make their way toward it. It is better to clear this dirt to ensure that the expert isn’t missing anything—ensuring that the surrounding soil is on the same level is enough. 
  • Insulation removal – we tend to mistake insulation for encapsulation in crawl spaces. Insulation covers cold floors alone, while encapsulation deals with general moisture and humidity problems. Hence, if you have an existing crawl space insulation, the expert will most likely remove it. 
  • Adding new insulation – insulation is still necessary for a crawl space, but the focus is on sealing this time. Experts know the insulation type that will work best with the encapsulating material, so they add it. 
  • Encapsulating material decision – this is the most crucial part of crawl space encapsulation. You can use different materials, but an expert will help you pick based on the functionality, effectiveness, and budget. 
  • Encapsulation location – generally, it is best to encapsulate every point of your crawl space for the best result if you can afford it. However, the cost can be high, so the expert will pick some prime locations based on their experience and your crawl space situation. 
  • Sealing encapsulation – most materials that encapsulate properly will not sit without some form of a seal. Hence, the expert will need to seal up this point.
  • Mold treatmentmold is a stubborn contaminant that doesn’t leave by simple cleaning; you need to treat it. Of course, the expert will have effective treatment methods to care for mold.
  • Blocking every entry or opening new ones – this step is peculiar to the needs of your crawl space. In some cases, the expert will add a new door for ventilation; sometimes, they may close the existing ventilation. You need to trust your pro on this decision. 
A professional outside a home inspects the vent leading to the crawl space as he prepares for crawl space encapsulation
  • Choosing a dehumidifier or humidifier – the expert will advise you to add a humidifier or dehumidifier based on the crawl space situation. Whichever one you buy should have a thermometer set to stop working when the room has reached the optimal recommended humidity levels. 

Crawl Space Encapsulation Materials

Installing crawl space encapsulation is not something you should try on your own. We know how cool and satisfying it is to do things yourself,  but sit this one out. Even the encapsulation expert will come with other professionals, including cleaners and gas testers. 

Three groups of materials are necessary for proper crawl space encapsulation, including:

  • Insulation materials
  • Sealing materials
  • Encapsulating materials

As we’ve explained, insulation is necessary before encapsulating the crawl space, as it helps its effectiveness. 

Different types of materials you can use for the insulation include: 

  • Rigid foam insulation 
  • Open-cell spray foam insulation
  • Closed-cell spray foam insulation 
A man in full protective gear is sitting on the attic floor while he sprays spray foam insulation on the underside of the attic ceiling.
Spray foam insulation is effective for crawl space encapsulation

We advise you not to choose fiberglass because of its reaction when it is wet. Fiberglass has a bad thermal performance when wet, which goes against the need for insulation. 

Sealing materials stop exterior air from getting into the crawl space and help hold the encapsulating material in place. Many people make the mistake of considering crawl space sealing as encapsulation.

We have written an extensive article on air sealing a home so you can better understand what air sealing is, and you’ll see how it differs from encapsulating a crawl space. Sealing deals with the lower parts of your crawl space, leaving the top at risk, while encapsulation protects the whole area while still sealing it. 

The most common encapsulating material used for crawl spaces is a plastic vapor barrier, also known as a polyethylene vapor barrier. Mostly, the plastic vapor barriers have a polyester cord, earning them the name heavy-duty plastic vapor barrier.

This material is generally used for encapsulation but has different types and corresponding features and specifications. The main difference between all types of plastic vapor barriers is their thickness. These materials come in thicknesses of between 6-20 mil

The lower the thickness of the plastic vapor barrier, the weaker it is at encapsulating the crawl space. The plastic vapor barrier with a 20 mil thickness offers you the best protection against all odds. This material resists puncturing, prevents pests, and controls moisture. 

Some of the factors you should consider when choosing the encapsulating material thickness include: 

  • The crawl space use – this consideration will determine how many times you visit the place and how much moisture will be in there. If you don’t do much there, between 10-mil and 20-mil encapsulating material is acceptable. 
  • Preferred timeline – you may be moving out of the home, requiring only a short-term solution. In this case, the 6-mil thick encapsulating material is okay. 
  • Floor-type – if you have a floor type that absorbs moisture like a rug, it invites pests, mold, and others. The 20-mil vapor material is necessary for such situations. 
  • Budget – 20-mil is the most opulent plastic vapor barrier—it’s the most efficient but also most expensive. If you’re on a budget, you can choose a vapor barrier of around 15-mil thickness to save costs. 
A vapor barrier roll, staple gun, and some staples resting atop a piece of plywood

Crawl Space Encapsulation: Time and Cost

Cost is the leading cause of people shying away from crawl space encapsulation. Encapsulation can cost anything between $1,500 and $15,000. This price may be high initially, but it saves you more over time if installed correctly. 

Some factors are essential in determining how much you will pay for your crawl space encapsulation. 

These variables include:

  • Present crawl space condition – how bad your crawl space is will affect the time and cost of clearing it. In turn, it will affect the total cost. 
  • Crawl space size – the bigger your crawl space is, the more materials you will require for the encapsulation, raising the costs eventually. 
  • The materials. Buying the insulation, sealing, and encapsulating materials come at varying costs. Quality materials usually have a higher price. 
  • Labor costs – first, hiring an experienced professional for the job is vital, but they come at a cost. Sometimes, they may need more hands to quicken the job, which adds to the price. 

Crawl space encapsulation is a job for professionals. A professional will not only do the job correctly but also save you time because of their available tools. It will take a professional less than three days to fix but can take you weeks or even months, with risks of mistakes. 


The vents installed in crawl spaces are the primary cause of moisture problems and high energy loss. 

If you already live in a building with a vented crawl space, encapsulation will help you solve the problem and save energy bills. It is not cheap, but it will prevent unnecessary energy costs in the future. 


Leave a Reply

Your email address will not be published. Required fields are marked *