How to Encapsulate a Crawl Space?

Old Crawl Space - Crawl Space Encapsulation Near Me graphic

The crawl space under your home is more than a narrow area for running wires and pipes. It’s where your home breathes since it’s where the house releases excessive humidity and draws in fresh, clean air. However, when crawl spaces bring in warm outdoor temperatures—which increases the chance of moisture damage—it’s time to consider crawl space vapor barrier encapsulation.

What Is Crawl Space Encapsulation?

Crawl space encapsulation uses a barrier to block moisture and heat from your crawl space. The tough polyethylene barrier wraps over the edges of your crawl space floor, walls, and ceiling, preventing pest infestations, fungal buildup, and subflooring deterioration. Encapsulating crawl spaces with a vapor barrier can help protect floor joists, any spray foam insulation, and your HVAC system from mold growth.  This helps keep your living space protected from moisture problems such as mold exposure or poor air quality.

If your crawl space is becoming problematic, trust Attic Projects for crawl space sanitation and insulation.

The Crawl Space Encapsulation Process

Materials Needed

The materials you use will determine the cost and the effectiveness of your crawl space encapsulation. The thickness of the insulation material also affects quality, with the 6-mil thinner option proving less durable than the 20-mil heavy-duty option. Some popular encapsulation materials include:

  • Closed-Cell Spray Foam
  • Open-Cell Spray Foam
  • Rigid Foam Insulation

You’ll also need fasteners, quality sealing tape that holds the encapsulation barriers together, and an underground drainage system to keep water away from your home.

Additional Resource: Encapsulate Attic

Tools Needed

Creating a vapor barrier in your crawl space requires protective gear, including eye and knee shields, construction gloves, and breathing masks. To encapsulate a crawlspace, you’ll also need:

  • Headlight or Flashlight
  • Utility Knife
  • Drill
  • Measuring Tape
  • Markers
  • Trash Bag


Step 1 – Prep The Crawl Space

If you decide to encapsulate a crawl space, the first step is to have the contractor analyze the current condition of the area. The structure should be sound and clear of debris. If your crawl space needs repairs, including removing old insulation or pests, do so before laying down the barrier.

Step 2 – Cover the Vertical Walls

After deciding on the best barriers for the project, insulate the surrounding walls to keep moisture-filled air out of your home. Insulate the ceiling to protect your upper floors, and insulate your floors since the earth holds high moisture levels.

Step 3 – Seal the Pipes

The next step in “how to encapsulate a crawl space” is sealing the pipes. Spray-on insulation fills holes and cracks around pipes and vent creases that bring outdoor air indoors, jeopardizing your insulation and home’s energy efficiency.

Step 4 – Address the Columns

When encapsulating your crawl space, the columns in your crawl space need smaller barrier sections that wrap around them. A professional installation contractor uses fasteners like bolts and screws to keep the barriers connected.

Step 5 – Roll Out the Barrier and Tape the Seams

Once you’ve set up the barrier, use a vapor barrier seam tape or another sealing tape to overlap the barrier seams for added protection.

Crawl Space Encapsulation Near Me

The Do’s and Don’ts of Crawl Space Encapsulation

If you want to see the difference between before and after crawl space encapsulation, there are some do’s and don’ts to follow for optimal effects.

  • Don’t encapsulate an open area. If you seal an area ineffectively, gaps let in moisture, risking the entire crawl space encapsulation. Instead, keep the area dry by sealing off all entry points for outdoor air before laying down barriers.
  • Don’t forget a drainage system. While moisture barriers keep dampness from the earth out of your home, your encapsulation won’t stand against underground flooding. Installing a sump pump or a French drain system that moves water away from your home’s foundation is a form of foundation waterproofing with a below average cost compared to the cost of repairing foundation walls. Sump pumps can prevent water damage before it happens by preventing standing water from accumulating.
  • Don’t choose your material on a whim. For instance, while fiberglass batt insulation is a cheaper alternative, it absorbs moisture and starts to sag and create holes in the insulation. This can lead to high humidity, causing wood rot and damage to the crawl space foundation.

The Crawl Space Encapsulation Cost

If you’re wondering, “how much does it cost to encapsulate a crawl space?” it averages about $7,500. However, how much it costs to encapsulate a crawl space depends on your crawl space size and current condition, alongside the materials you prefer, extending the price to $20,000 or more.

Depending on your location and building codes, you may need a permit, and prices range between $100 and $250. Next, you may have to pay $1,500 to $15,000, depending on the extent of renovations. Finally, your choice of contractors and materials determines the remainder of the crawl space encapsulation cost.

Benefits of Crawl Space Encapsulation

Your house’s wooden frame rots with prolonged exposure to dampness, deteriorating your flooring and structure over time. What’s more, termites and other harmful pests thrive in humid and moist environments, furthering damage, but those aren’t the only problems with moisture.

Limiting moisture in your home with crawl space encapsulation reduces:

  • Mold, mildew, and other fungal buildups
  • Allergens in the air that seep in from outdoors, improving your health
  • Offputting smells from stagnant water or damp walls and floors

Frequently Asked Questions (FAQs) – The Crawl Space Encapsulation

What is the Difference between Crawl Space Encapsulation and Insulation?

Unlike insulating your foundation, professionals line the interior of the crawl space rather than outside the foundation wall. Installation of this crawl space vapor barrier blocks moisture and humidity, while the crawl spaces insulation solely keeps tile and wood floors more comfortable during cooler months.

Does an Encapsulated Crawl Space need a Dehumidifier?

After sealing your crawl space, a dehumidifier keeps the under part of your home conditioned. That way, even if moisture seeps in from the air or ground, the product reduces moisture levels to under 50%.

Is Crawl Space Encapsulation covered by Insurance?

Your standard homeowners’ insurance may not cover your crawl space encapsulation. However, as an energy-efficient project, you may receive a tax refund or rebate from your local or state government.

Crawl Space Encapsulation Near You

Before starting your crawl space encapsulation, you may have many questions, from “how much is it to encapsulate a crawl space?” to “how long does it take to encapsulate a crawl space?”

At Attic Projects, our experienced in-house team understands you want the best at competitive prices. Our insured, bonded, and licensed crawl space encapsulation pros are available 24/7 to clear out old problems while preventing new ones from forming with our encapsulation installations and replacements. Call us for a free inspection today!

Recommended Article: How To Install a Crawl Space Drainage System

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