What is the best material to use for a vapor barrier?
You can make a vapor barrier out of any unbroken surface that’s impermeable to water vapor. Polyethylene plastic is a good material to use, in a thickness between 0.002 and 0.008 inches (0.05 to 0.2 millimeters).
What is a good perm rating for vapor barrier?
A perm rating of less than 0.1 is considered a Class I impermeable vapor retarder (which is also considered a vapor barrier); perm rating between 0.1 and 1 is considered a Class II semi-permeable vapor retarder; a perm rating between 1 and 10 is a Class III permeable vapor retarder; and a perm rating greater than 10 is …
What can I use for vapor barrier?
What can I use as a vapour barrier?
- Elastomeric coatings.
- Aluminum foil.
- Paper-backed aluminum.
- Polyethylene plastic sheet.
- Asphalt-coated Kraft paper.
- Metallized film.
- Vapour retarder paints.
- Extruded polystyrene or foil-faced foam board insulation.
What is considered a Class 1 vapor retarder?
A Class I vapor retarder is a material with a permeance less than 0.1. crawl space, with a liner of 0.1 perms allows over 4 gallons of moisture vapor to pass through in a year.
Is Tyvek a vapor barrier?
No, DuPont™ Tyvek® is not a vapor barrier. It is made with unique material science to keep air and bulk water out while allowing moisture vapor inside walls to escape.
Should you put plastic over insulation before drywall?
Normally interior walls do not require a vapor barrier, but there are some situations where it is highly recommended. A continuous plastic vapor barrier behind the drywall will protect the interior walls of these areas from water damage.
What is a Class 3 vapor retarder?
Class III – Medium permeability vapor retarders – rated greater than 1.0 perms and less than or equal to 10 perms. Latex or enamel paint qualify as Class III vapor retarders.
What is a Class 2 vapor retarder?
Class II vapor retarders are typically Kraft paper (Kraft-faced insulation). The permeance of Kraft paper increases to Class III levels at higher relative humidity (from 0.3 up to 3 perms). Typical perm ratings for common building materials are shown in Table 2. Permeance typically decreases with increasing thickness.
Is drywall a vapor barrier?
The permeance of unpainted drywall is very high, generally between 20 and 90, so it’s not a vapor retarder at all. Nearly 100 times as much water vapor goes through the hole in the drywall by air leakage than goes through by diffusion.
Is 15 felt a vapor barrier?
A vapor barrier is a product that would stop all water vapor from passing through it. It’s better to use the term vapor retarder as there are many products that slow down the passage of water vapor through them. A technical white paper produced in 2011 shows that #15 felt paper has a vapor permeance rating of 7.
Is house wrap a vapor retarder?
For example, House wrap by itself is not an air barrier, it is a vapor barrier. However, IF installed properly, which is rare, with taped seams, bottom, top edges, and no tears, it acts as an air barrier. So primarily it acts as a vapor barrier, but installed properly can do both; vapor barrier and air barrier.
Does vapor barrier cause mold?
The Problem With Vapor Barriers This can lead to significant moisture problems and mold; problems occur when walls get wet during construction or more often throughout the home’s life.
What is a vapor retarder?
Now, a vapor retarder is defined by the International Residential Code (IRC) as “a vapor-resistant material, membrane, or covering with a perm rating of 1 or less.” That definition might not make things any clearer to you, frankly.
Is Visqueen a Class 1 vapor retarder?
Sheet polyethylene (visqueen) or unperforated aluminum foil (FSK) are Class I vapor retarders. Class II – Low permeability vapor retarders – rated greater than 0.1 perms and less than or equal to 1.0 perms.
Are vapor retarders required in all climate zones?
The IRC does not require or prohibit the use of vapor retarders in climate zones 1, 2, 3, and 4. NAIMA recommends using either a Class II or III vapor retarder in these warmer climate zones and avoid the use of Class I (very low perm) vapor retarders. Kraft-faced batts can be installed in all climate zones.
Do I need a vapor retarder on my frame walls?
The International Residential Code (IRC) requires either a Class I or II vapor retarder on the interior side of frame walls in climate zones: 5, 6, 7, 8 and marine 4 (see climate zone map).