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Steps to Install Vapor Barrier to Seal Out Moisture

Installing a plastic vapor barrier is a logical way to protect your home's foundation. Get a step-by-step guide to installing a vapor barrier system in your home.

Crew carrying wall seal roll

Your crawl space is commonly a place you never go. It’s damp, dusty, and all around dirty. But what if that wasn’t the case? What if you could seal the outside dirt and grime out using a vapor barrier and create a clean, dry usable space for storage?   

It is possible, but installing a vapor barrier is only part of the solution needed for a transformed crawl space. The repair takes a large amount of preparation and a lot of hard work.  In this article, we’ll explore why installing a vapor barrier is beneficial, but encapsulating your crawl space is the best and only permanent solution.  

Why Installing a Vapor Barrier is Important? 

With around 15 percent of the homes built since 2013 having been constructed over crawl space, it’s important to understand why installing a vapor barrier in your home is important.   

Moisture is your home’s largest enemy. Water, or water vapor, seeping from your untreated crawl space to the wooden structural supports of your home can mean serious problems like mold, wood rot, and loss of structural integrity. A wet, damp crawl space is also an ideal breeding ground for insects and rodents.   

Sealing your crawl space and incorporating it into the envelope of your home is the only way to be sure your family is breathing clean, conditioned air and the wooden supports of your home are safe.   

That being said, installing a vapor barrier alone isn’t enough. Encapsulation, which includes addressing any water problems, insulating crawl space walls and possibly dehumidifying the air is the only way to see a permanent solution.  

How a Vapor Barrier Works? 

A vapor barrier is a simple way to seal out moisture in your crawl space. According to the US Department of Energy, controlling the moisture in your home can make your home more energy-efficient and less costly to heat and cool.   

A vapor barrier does just this. When this plastic sheeting is installed properly, it prevents moisture from entering the crawl space and causing problems.   

It is important to note that in order to gain the full benefits of a vapor barrier, the crawl space must be sealed completely, meaning no outside air can enter from the walls, vents, or floor.  This is where encapsulation from a trusted foundation company like Groundworks comes in.  

Is Mold Removal Necessary First?  

One of the common crawl space red flags is mold. Mold is often the first indication of a problem. So, is it important to remove the mold before installing a vapor barrier?  

Maybe. The answer depends on how long the problem has been festering and how much mold is present at the time of installation. The United States Environmental Protection Agency says if mold is less than 10 square feet (or a 3ft. by 3ft. area), the mold can be cleaned yourself. They suggest a mold remediation company to address the issue if the area with mold is larger.   

Mold commonly needs three things to survive, water, food, and oxygen. Without these three elements, mold will cease to exist. Since oxygen and food, dead organic materials like wood, aren’t going anywhere inside your crawl space, if you remove the water element, mold will die.   

Installing a vapor barrier during encapsulation removes water from the equation, still, if your crawl space has a large amount of mold, it’s a good idea to have it removed by a professional before moving forward with a vapor barrier installation.   

How to Install a Crawl Space Vapor Barrier Step by Step

As mentioned, installing a vapor barrier is one step in the overall encapsulation process.  Below you’ll learn the grueling steps of encapsulation installation and see why it’s essential to keep outside air out.  Your local Groundworks team has repaired nearly ten thousand crawl spaces this year alone. Avoid the dirty work, our experienced team is in and out of your home, leaving your crawl space, clean, dry and ready for storage.  

Before installing a vapor barrier, it’s important to do a full foundation inspection and determine the cause of the crawl space problem. Is groundwater entering from the floor or walls? Are open vents trapping humid air inside? Is a plumbing leak dripping into the space? Ensuring the solution matches the root problem goes a long way to preventing future problems.  

Your local Groundworks inspector will consider your neighborhood’s unique soil type, the typography of your home, and the weather conditions before making repair suggestions. 

Depending on the condition of the crawl space, this step may look different for everyone. If your crawl space is wet, it’s beneficial to dry it out with a submersible pump, fans, or a dehumidifier. This process may take a while. Consider mold remediation if needed.  

All fallen insulation and scrap building material should be bagged and removed. 

The floor of the crawl space should be clear of large rocks and debris. The soil should be raked to establish a rough grade.   

Depending on the amount of water in your crawl space, consider installing a specially designed crawl space sump pump or other drainage options to remove any water that would remain beneath the vapor barrier.   

The climate and the amount of energy saving you wish to see will determine the proper wall insulation needed at your home. Regardless, all vents should be sealed completely, and either a ridged wall board insulation or high-quality vapor barrier should be attached to the crawl space walls using a masonry fastener.   

All seams that allow air to enter the crawl space should be sealed using quality polyurethane foam.   

To prevent cold air from entering the crawl space, install R30 Fiberglass insulation into the bond cavity.  

Measure and cut a high-quality vapor barrier to fit the crawl space and allow several inches to run along the walls. Be sure to overlap seams for taping.   

Use a two-sided butyl tape to create an airtight seal on all seams. Finishing tape should be used to provide a clean finish on the walls, floor, and support columns.   

Now that your crawl space has been sealed, you need to establish a positive airflow. This can be accomplished by tapping into your HVAC unit or installing an energy-efficient dehumidifier.   

Groundworks: Vapor Barrier Experts  

While the solution to install a vapor barrier in your crawl space is fairly straightforward, the job can be exhausting, back-breaking work. With crawl spaces often being tight, small places, it’s not uncommon to be working on your back or stomach during the duration of the work. This doesn’t mention the numerous trips through the crawl space access point, which can be difficult.  

The experts at Groundworks install vapor barriers and encapsulate crawl spaces every day. In fact, in the first eight months of 2022 alone, we have repaired nearly 8,000 crawl spaces nationwide. This has allowed us to establish the best products and procedures to make installation as simple and effective as possible.  Our 20 mil CrawlSealTM liner locks out moisture and soil gases and comes with a nationally backed, long-term warranty.  

If you’re noticing sagging floors or high energy bills, your crawl space problem won’t get better with time. Let Groundworks install a vapor barrier and encapsulation system to seal and eliminate your crawl space problems.  

Let us do the hard work. Call to schedule your free inspection today or book online. Schedule a time and date to have an inspector put eyes on your problem and suggest solutions that don’t involve you losing your weekend beneath your home. 

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