What is a Crawl Space Vapor Barrier? Do I Need One For My NJ Crawl Space?

crawl space vapor barrier

If your South Jersey home or business is on a crawl space with a dirt floor, a properly installed crawl space vapor barrier can be the solution to a number of common moisture related problems. You see, dirt or sand floors emit moisture or water vapors all year-round. This is especially the case if you have a high water table, which is true of most New Jersey areas. These vapors rise with normal air currents in you crawl space and eventually wind up clinging to your wood floor joists, sub-flooring and insulation.

A crawl space vapor barrier is a layer of plastic installed over the dirt floor of a crawl space. A crawl space vapor barrier controls crawl space moisture levels by slowing or preventing the evaporation of ground moisture into the crawl space air.

Signs of Excessive Moisture in Your NJ Crawl Space

It is important to check your New Jersey crawl space at least twice a year. Additional checks in between may be necessary if you experience a lot of rainfall in your South Jersey area or you live in an area will a higher water table. Look for the following signs of potential moisture problems:

  1. Standing water or mud after a heavy rain– Excessive standing water should be promptly addressed to prevent water damage and mold damage.
  2. Efflorescence on crawl space walls– Efflorescence is a crystalline deposit (often mistaken for mold) on surfaces of masonry, stucco or concrete. It is the result of salt deposits from water exposure. If you see efflorescence on the interior side of your crawl space walls, it is a sign that water is seeping through your walls and leaving behind mineral deposits.
  3. Unpleasant musty odors– A musty odor can be an indicator of water damage and serious mold contamination. If you detect musty odors, you might want to consider consulting a mold inspector in your South Jersey area. If odors are permeating through to main living spaces, mold testing may be necessary to determine the full extent of the problem.
  4. Pealing paint on exterior of home– The most common reason for peeling paint is water. If water vapor condenses underneath the primer or finish, pressure will result causing the paint to lift from the surface and crack.
  5. Insects and other pest infestations– Insects are attracted to the moist environment coupled with all the available food. Insects feed on mold growth, wood rot, and various other dead material that can be found within your crawl space.

When it comes to crawl space moisture, early detection and action can be the key to preventing serious and costly water damage and mold damage.


Problems Caused by Moisture in South Jersey Crawl Space

If you detect moisture problems in your crawl space, you need to address them right away. Unaddressed moisture will reek havoc on your crawl space and leave you with serious problems like the following:

  1. Mold development– With the right conditions, crawl space make a great environment for mold growth. Unaddressed crawl space moisture can mean serious South Jersey crawl space mold. If mold growth in the crawl space is neglected and the water problem remains unaddressed, the mold growth can easily spread and become a widespread contamination that needs to be handled by a professional crawl space mold remediation company in NJ.
  2. Water Damage– Water vapors may seem harmless at first, but given time, excessive water vapors can develop into major water damage. Moisture buildup can lead to mold development and structural damage to the property, which can compromise the structural integrity of the home and render the home unsafe.
  3. Wood Decay– With time, water vapors absorbed into the building materials in your crawl space will begin to destroy the structural integrity of the building materials. Wood decay ruins the homes support system and it lures insects to feed on the rotting material, leaving you with an unsafe and insect infested home.
  4. Low hanging insulation that can no longer properly insulate your crawl space– Moisture compromises the structural properties of insulation. Water vapors can force insulation to drop, leaving it useless for its intended purpose.


Proper Crawl Space Vapor Barrier Installation New Jersey

In order for a crawl space vapor barrier to function properly and do its job, it needs to be properly installed.

  1. A properly installed vapor barrier should be thick enough (10mm at a minimum) to prevent damage from people (and animals) crawling on it.
  2. Plumbers, electricians and even the cable company carries tools that are capable of ripping your valuable vapor barrier, so be sure to tell them to be careful when crawling around down there.
  3. “Properly installed” means that the floor should be excavated if necessary to ensure it is as flat as possible.
  4. Once the vapor barrier has been measured and cut, all the seams should be attached using a spray on adhesive that resists moisture. This should be reinforced by taping the seams with a sturdy, moisture resistant tape.
  5. If your NJ crawl space is prone to flooding, then your vapor barrier should be perforated in several areas to allow water to drain into the soil. The small drain holes may seem counter-productive, but they are necessary and will not allow enough moisture to cause a problem.
  6. If your foundation walls are seeping or sweating, then you may want to cover them too. In that case, your vapor barrier would extend up the walls and piers high enough to cover any block or masonry.
  7. Ultimately, you’ll want to have the walls inspected by a qualified contractor to make sure they are in good shape – and to make sure you don’t need a more aggressive solution like a perimeter drain.

Depending on the natural environment surrounding your South Jersey residence, you might need more than just a crawl space vapor barrier to prevent moisture issues in your crawl space. In areas that experience higher humidity levels, like most areas of New Jersey, you should consider installing a properly rated crawl space dehumidifier in addition to the crawl space vapor barrier to ensure controlled moisture levels.  Proper crawl space moisture control might require a strategic combination of tactics.

In addition, you should make it a habit to regularly check your crawl space for any maintenance opportunities and signs of problems. If your pipes and sewer lines travel through your crawl space, check them regularly to ensure they are in good condition and not at risk for leakage. Early detection of any crawl space issues can help South Jersey homeowners avoid a costly south jersey crawl space mold removal project.


  • Thomas Duff

    Thomas Duff, the visionary founder of MasterTech Environmental, brings a wealth of expertise and passion to the forefront of our mold remediation and biohazard cleanup mission. With a profound commitment to setting new industry standards, Thomas leverages his hands-on experience and innovative spirit to lead MasterTech Environmental to unparalleled success. Overseeing not only the original Blackwood, NJ location but also the thriving MasterTech Franchise Systems, Thomas champions a tight-knit family of professionals dedicated to serving communities, cultivating honorable trades, and ensuring customer satisfaction. Recognized for our presence on HGTV and DIY Network, Thomas Duff's dedication to excellence has driven our company's exceptional client ratings on Google and other review platforms. With a clear vision, unmatched passion, and a commitment to continuous improvement, Thomas Duff continues to lead MasterTech Environmental into a successful future in the restoration industry.

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