Though going with a thicker vapor barrier generally comes at a higher cost upfront, it'll also offer greater long-term value and durability.
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. This translates into a permeance rate of only . 0015 This is considered impermeable in American building codes.
The bigger the number the thicker the plastic. Plastic sheeting comes in ranges from 1 mil to 100 mils! A "mil" A mil is a measurement that equals one-thousandth of an inch, or 0.001 inch.
15-mil vapor barriers are slightly thicker and more durable than 6-mil, 10-mil, and 12-mil liners. However, they are not comparable to the heavier, more robust 20-mil vapor barrier.
ALUMINIUM FACED VAPOUR CONTROL LAYER
It is a great option, due to its durability, waterproof barrier and non corrosive upper and lower layers. Moreover, it offers radiant heat-resistance by up to 97%, stability and tear-resistance.
Select a vapor barrier with the appropriate permeability rating for your project. A lower perm rating is better for areas with high moisture levels, while a higher perm rating might be suitable for less critical applications.
Don't Install a New Barrier Over Old Plastic
If your home already has a plastic vapor barrier installed, don't just install a new one over the top of it.
Polyethylene Sheathing: Best For Crawl Space Floors
The best solution for a vapor barrier on your floor is polyethylene sheathing.
Why Do Builders Need an Underslab Vapor Barrier Plastic? An underslab vapor barrier protects the subfloor and, subsequently, the main floor from moisture by adding a protective layer underneath the concrete foundation before it is poured on wet. There's water in the ground underneath every building.
In most cases, crawl space vapor barriers should be at least 12 mils thick poly, but it depends on the floor, how often the crawl space will be entered along with if the crawl space will be used for storage.
HEAVY DUTY OUTDOOR TARP: This 10mil thick tarp is sure to endure the test of time. Made from premium polyethylene material for durability and strength.
Wear layers are commonly 6, 12, 20, or 22 mils thick, and their thickness is measured in mils. As you would have imagined, the flooring will be more durable the thicker the wear layer. The 20-22 mil thickness can actually withstand commercial environments.
Extend vapor retarder at least 6 inches up walls, columns, and footings. Use physical attachments where practical and necessary for long-term adhesion of vapor barrier to vertical surfaces. Overlap all seams at least 12 inches using a reverse or upslope lapping technique.
It should remain tight in winter when humidity in the cavity is low to prevent moisture from entering but also needs to increase permeability in summer to let moisture escape, helping to keep the wall dry.
Through research and testing, top experts have determined clear plastic is not optimal, as it exposes the soil to sunlight and can be conducive for plant growth under your home. If your home has a clear vapor barrier, consider replacing it with a black 6mm one.
Because a vapor barrier is a low permeable barrier, it keeps moisture from passing through. This is beneficial to keep moisture away from a dry surface but will trap moisture behind it if installed on a water-damaged concrete wall, causing the wall to fail further.
Materials such as rigid foam insulation, reinforced plastics, aluminum, and stainless steel are relatively resistant to water vapor diffusion. These types of vapor retarders are usually mechanically fastened and sealed at the joints.
Vapor barriers should be at least 6 mil in thickness to effectively cover the area and create a moisture barrier.
Tara liners one of the leading pool liner manufacturers in the world recommends only 20 mils. They actually state on their website “Although, 27, 30 even 40mil liners are available, we do not recommend using anything thicker than 20mil. A thicker liner may not conform to the shape as well.
The most basic option available, the Class 1, 6-mil polyethylene sheeting often found in hardware stores, boasts a perm rating of approximately 0.06. This vapor barrier represents the minimum mil thickness accepted by building codes for crawl space ground cover.
However, if not installed correctly or if damaged, vapor barriers can actually contribute to mold growth.
A high-quality crawl space vapor barrier can be an effective solution for many years, as long as it is not damaged or punctured along the way. Generally, a crawl space vapor barrier that has been correctly installed by a professional and made of high-quality materials can have a lifespan of 20 years or more.
Yes, double vapor barriers are counter-intuitive but they do work – within the limits noted above – especially the points about humidified and pressurized buildings and control of condensing surface temperatures6.