All About Vapor Barriers

A vapor barrier is an impervious membrane that prevents the flow of moisture through a building envelope. The main purpose is to block the passage of water vapor contained in the air. It is installed together with insulation as they affect each other and need to be installed properly on order to interact beneficially.

The vapor gets into the building cavities through diffusion through materials, air currents and heat transfer. However, the air movement contributes to the highest percentage of the water vapor.

The specific functions of vapor barriers include:

  • · Protection of the envelope structure and insulation from condensation damage. This is because most of the wall materials are permeable to the water flow from the inside to outside and vice versa. On a cold day, the water vapor from the inside of the building moves outward via the wall thus encountering increasingly lower temperature. The vapor starts to condense damaging all the types of envelope structures. Furthermore, steel structural members rust, wood structures rot and freeze cracking of any masonry. Vapor barriers block the water vapor thus preventing condensation.
  • · Prevent air leakage through the envelope. A proper-installed vapor barrier greatly reduces or prevents air leakage via the envelope surfaces. This is important even though the air current inside the envelope itself is not reduced.
  • · Maintain interior humidification. In case where humidification is used, vapor barriers reduce the amount of water and energy needed to maintain the preferred level of humidity.

Crawlsapce 1800 pic

The common vapor barrier material is 6-mil polyethylene plastic film. This material is easy to handle, inexpensive and available in wide widths . It is easily attached by mastic, stapling or other means. Many commercial installers will use an engineered plastic sheeting vapor retarder that is thicker, and tested to withstand degradation.   In areas where there is radon- a leading cause of lung cancer, installers will use vapor barriers that will essentially block the radon from coming up through the liner. These tried, tested and true vapor barriers can be found from plastic sheeting companies that specialize in engineered vapor retarders. These methane blocking liners are utilized in crawl spaces.  Other materials used include paper-backed aluminum, aluminum foil (0.05 US perm), asphalt coated Kraft paper (0.40 US perm), metalized film and other new materials. The vapor barriers are attached to permeable insulation such as blankets or glass fiber batts.

Vapor barriers should be installed on the warm side of the insulation; condensation occurs as water vapor circulates from the warm side to the cold side of the wall. If installed on the cold side, moisture is trapped inside the envelope worsening the moisture problems.

Today, improper use and design of vapor retarders leads to moisture-related problems in buildings. When designing water vapors, develop a thermal section of exterior roof or wall, determine the dew point for the inside environment and locate the dew point in the wall.

The vapor retarder continuity should be checked for corners, penetrations and junctions at the interior plane around the building envelope. Laps and penetrations should be sealed continuously.

When used for floor, the polyolefin membranes should be used other the polyethylene. It should be placed under the slabs and the slabs covered with damp burlap to reduce any curling risk when drying and curing.

For awkward and hard to reach areas, spray foam insulation should be used. Additional spray is used to provide a smoke or fire seal. Additionally, double vapor barriers should be used where they can be perfected such as roofing, curtain wall construction and gazing. This is because; damaging moisture may mount up between faulty vapor barriers.

Why Does Your House Need Crawl Space Vapor Barrier?

Almost in each and every house there are crawl spaces having vapor barrier on the grounds. This is certainly not the best way to do it. Few amount of moisture come from the ground but mostly they are borne in air. To overcome this moisture problem, a particular number of vents are specified for Crawling Space Vapor Barrier, but there are a large number of shortcomings of all kinds. These not only cover the ground with the vapor barrier but they also seal the walls of crawl space.

About Crawl Space Vapor Barrier

If you don’t have ventilation in your house then it might be a bad idea to seal the crawl space. This is because by doing that the sealed space becomes a stagnant and close area which can’t be cleaned. But if the ventilation is there then by sealing, after a heavy rain it can have standing water and the ground will stay dry forever unless the vapor barrier is not installed there.

Related: Why Crawl Space Vapor Barrier is The Best

How Crawl Space Vapor Barrier Works?

Absolute humidity is the real mass of vapor which is present inside the air water vapor mixture. Hence sometimes when the Crawling Space Vapor Barrier has good ventilation, no vapor barrier and standing water after each heavy rain it is always observed that the water vanishes after few days. No mold whatever is seen and ground becomes dry. So it produces these advantages-

  • Air quality of living room space improves.
  • Elevated appearance value of the house may grow up.
  • Comfort level is raised as opposed to the slab.
  • Foundation’s piers, post and support pilings can become dry now.

There are so many reasons to use Crawling Space Vapor Barrier. It gives a plus to your house in all round formats such as attraction, plumbing, electrical, air conditioning and many more.

How To Install Crawl Space Vapor Barrier?

Hello, I am a 39 year old sales person from Minnesota and I specialize in installing crawl space vapor barrier in various places as per my company’s wishes and chores. As my job description goes, I am responsible for installing this equipment along with my team of workers, and make sure that it is completely accessible as well as completely operational. 

Installing a quality vapor barrier is the prime concern of my job. Now, having spent almost 18 years at my job, I have become quite experienced as to determine how to successfully install a vapor barrier, without much hassle or any such problems. Let me tell you something, installing a vapor barrier is not a physical difficulty at all. It just requires precision as well as finesse while setting up the job.

The first step

Such jobs of installing a vapor barrier may include other implications as well. This may include additional jobs to install a crawl space vapor barrier or encapsulating an entire crawlspace area. Time is not a very big factor here, and if the job is done right, it only takes a little time. The first and foremost thing that one needs to do is to get or purchase a vapor barrier. There are many places from where one can buy one.

In today’s age, even some internet sites also sell such items in their websites, and purchasing off the internet is very easy and amiable as well. Products in such sites may vary from cheap ones, to rather posh and expensive ones as well, according to the needs of the customer. Cheap and inexpensive ones can also be purchased from any local hardware stores as well. Other than that, retail options regarding types of crawl space vapor barrier are also available.
If you ask for my opinion, I would ask you to go with moderately priced vapor barriers, because the inexpensive ones are easily subjected to wear and tear. The fitting standards are also questionable, and they become brittle and crack. Moderately priced options have considerable warranty periods that range approximately to 25 years, so there is no question regarding the credibility of those items.

Installation of vapors

After those vapors have been purchased, the next step involved is to provide the base for appropriate installation. One should cover those floors, and seal them off. In addition to that, some water-proof tape is also required to seal those seams of vapor barrier. A crawl space vapor barrier installation involves sealing those floor materials as well around foundation places.

Then, those plastic sheeting piers that are present should be adequately wrapped with any appropriate material. Proper construction tools should be used so that labor can be minimized. After those piers have been sealed off successfully, the final step involves sealing those crawl space walls to those floor materials. For most of these sealing methods, a combinational adhesive consisting of mechanical fastener is used.

Advantages

In case of a complete encapsulation, labor associated is a bit more. In case of an encapsulation, that entire wall area should be sealed so that effective pest control measures should be undertaken. Along with that, a wall liner is also used. Following are then advantages of installing your own crawl space vapor barrier. They are:

  • Saves labor and time.
  • Assists in financial restraints.
  • Provides self-dependence for future prospects.
  • Makes proper arrangements of the house.

Having said that, I would like to say that being a construction and installation worker, I would suggest that prior research should be done before one actually tries his hand at this job. Knowing about the infrastructure can surely help the concerned to do a much better work in installing a crawl space vapor barrier.

Why Crawl Space Vapor Barrier Is Better Than Other Installation Methods?

As just because of my job concerned I shifted from my old house to new place as it was near to my office. I wanted a house with less expensive that fits under my budget. I brought house with crawl space basement from house broker by doing some compromises, because it fit to my budget. My neighbor was too friendly, he told me to apply crawl space vapor barrier as he did, to avoid the damage it would cause; explaining the reasons that might arise.

Reasons that arise for crawl space:

  • The vents being left open
  • Floor having Fiberglass insulation on it
  • Wet areas or standing water
  • Metal rusted surfaces
  • Damp or dirty insulation
  • Mold that are visible and smells bad in rotted wood or crawl space
  • In winter floors getting cold above crawl space
  • Rodent pests or insect

I have already heard about some of the reasons about crawl space vapor barrier, but if my neighbor would have not reminded me, I would have ignored it. And later I would have got in trouble; that’s for sure. As mostly the symptoms are seen in summer and humid spring seasons. Later, I read it about the problem that could persist in crawl space basements as I am also one of those living in such house.

Problems that persist in crawl space:

  • In crawl space vapor barrier, due to heavy rainfall, the floor might get filled with mud dirt and standing water.
  • Musty odor forms unpleasant smells in living area.
  • Rust and rot occurs.
  • A level of radon gets higher.
  • Exterior house paint might get peeled.
  • Health problems like headaches, discomfort, illness, respiratory kind of allergies and asthma may exist.
  • The closets of first floors wall and floor may get damaged with mildew and mold.

The conventional wisdom and building codes have permitted ventilation as primary moisture control method, but it’s not a good idea the problem may get worse. Various different methods are there to manage and maintain the house foundation, but I found crawl space vapor barrier perfect for mine.

Solutions:

These are the solutions to crawl space vapor barrier problems.

  1. Ventilation covers: It helps to keep excess amount of moisture out, so as to build healthier environment.
  2. Insulation: The foam insulation allows improving comfort and is energy efficient. The rigid foam is installed against the crawl space wall which does not fall out of place or looses R-value. Also they don’t get damaged by moisture.
  3. Drainage pipe system: It depends on condition which kind of component to be used. During rainy days or when leakage from ground water, the standing water and dirty floor creates muddy mess. This drainage system helps to end crawl space moisturizing problems.
  4. Access door: These are meant for below grade crawl space door to protect from pests and unwanted moisture.
  5. Vapor barrier: It does consist of an anti microbial agent that is blended on its liner that helps to kill bacteria and mold. It blocks most of harmful gas movements known as radon from soil.

Crawl space sealing is the best way treatment to turnover dirty, moldy, damp surface into clean and dry space to avoid mold’s to get grown. If insulating crawl space then I think Fiberglass insulation is not the right choice material as it absorbs moisture which may be the reason to attract mold and promotes wood rot. Damp surface having Airborne mold spores and dust mites in it, is also among the one common reason to pollute indoor air and allergens.
To keep house and environment safer especially first floor living people, when staying in such crawl space foundation basement area, crawl space vapor barrier must be installed to protect it from harmful gases, small species and animals like; termites, rats, insects and also fungus that damage the base of house.