Codes for residential applications often cite a 6 mil (0.006-inch thick) minimum vapor barrier. However, we recommend a 10 mil or higher for crawl space applications.
It can also carry with it foul odors from the soil as well as fungi that can rot the wood structure of your home. By sticking with a thicker mil plastic, you'll have a dryer crawl space and better air quality. We recommend using a vapor barrier of 16 mil or higher.
In humid climates, 3 mil Visqueen or a 4 mil poly vapor barrier will help cool the home, but the thinner the barrier, the easier it will tear. 6 mil vapor barrier polyethylene is what you're looking for in most cases. Even for use as a simple drop cloth, it would be wise to go with a 6 mil vapor barrier minimum.
Although 6 mil is the minimum standard, the crawl space environment may require a thicker material to effectively block moisture and gases. Not every plastic sheeting that is 6 to 20 mils thick behaves as a vapor barrier.
For crawl spaces, 6 mil thick vapor barriers are generally the minimum, but if the ground is rocky or it is being placed in a high traffic area, a thicker plastic sheeting may be necessary. If you are placing a vapor barrier under concreter floors or slabs then the minimum thickness generally is 10 mil.
Vapor barriers should be at least 6 mil in thickness to effectively cover the area and create a moisture barrier.
This 8 mil thick plastic sheeting can be used in multiple applications. It can be used to cover and protect surfaces when painting or curing concrete. As a vapor barrier in interior walls or in crawl spaces. Covers up to 2000 sq ft.
Additionally your crop may be damaged or ruined. In summary, 6 mil poly will get you by for potentially four years, save you money for its purchase, but require your labor and time to recover every 3-4 years or sooner if it tears.
Clear 6 mil Greenhouse Plastic is the most commonly installed greenhouse cover since it provides a long lasting cover (4 plus years) at an affordable price.
Black barriers are more effective at stopping moisture evaporation, compared with the clear barrier. The black color hinders the growth of plant seeds that may reside beneath a home's crawlspace. Plants naturally send moisture into the air, creating more moisture.
Plastic Sheeting is a is a general-purpose plastic film for use in a variety of construction and DIY applications. This extra heavy-duty film can be used as a vapor barrier for concrete, under wood floors and even to cover crawl spaces. Commonly used between drywall and insulation.
The bigger the mil "usually" the stronger the plastic sheeting. There are exceptions to this. When you add string or scrim as it is called to the plastic a 6 mil string reinforced plastic sheeting film is stronger than a regular 6 mil plastic sheeting film.
Vapor Blockers
Vapor barriers—sheets of plastic or kraft paper—keep water vapor out of the wall cavity, so the insulation stays dry. Not every type of insulation needs a vapor barrier. But if it does, the barrier should face inside in northern, heating climates, and outside in humid southern climates.
Cons: This material is fairly flimsy and can be easily damaged during installation. It incorporates limited resistance to punctures and tears. Any penetrations, such as for an electrical junction box, must be taped and sealed in order to form an effective barrier.
A minimum 125 micron thick (500 gauge) polythene sheet.
The bigger the number of mils, the thicker the plastic sheeting. Here are some approximations with common items to help you understand. Four (4) mil plastic sheeting is about as thick as a piece of paper. Six (6) mil plastic sheeting is what your trashbags are made from in your kitchen.
Super tough, fully waterproof 4 mil plastic sheeting is wrapped on a solid core. Size is 10' x 25' with a 4 mil thickness. 10' x 25' Plastic Sheeting has a 4 mil thickness.
Clear Poly Sheeting - Heavy Duty, 6 Mil Thick Plastic Tarp – Waterproof Vapor and Dust Protective Equipment Cover - Agricultural, Construction and Industrial Use (10' x 100')
Multi-Purpose - Our 10 mil black plastic sheeting can be used as a moisture barrier, vapor barrier, protection barrier for painting, dust containment, spray barrier and more! This 4mil black sheeting plastic is great for covering and protecting lumber, equipment, and any type of machinery.
Is DuPont Tyvek a vapor barrier? No, DuPont Tyvek is not a vapor barrier. It is breathable, allowing moisture vapor to pass through it.
Beginning at one side of the crawl space, lay down 6-mil or thicker polyethylene plastic over the entire crawl space. Cut the sheets to size, allowing 6 inches or more along walls. Overlap the seams by no less than 12 inches and secure them together with the poly PVC tape.
A vapor retarder that is torn or punctured provides a pathway for moisture to enter the slab from below. The American Concrete Institute's Guide for Concrete Floor and Slab Construction recommends that the thickness of the vapor retarder be at least 10 mils.
Warm and Humid Climate
The IRC doesn't require vapor retarders or vapor barriers when homes are in a warm-humid or mixed-humid climate. However, if installing these materials, you should install them on the exterior.
Stego Wrap 15-Mil Vapor Barrier has an extremely low permeance rating, which helps mitigate the risk of water vapor accumulation and the transmission of various soil gases. This helps to maintain the integrity of the building envelope and promotes indoor air quality by avoiding serious moisture-related issues.