Does Roxul Need A Vapor Barrier In Attic

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.

Does roxul need a vapor barrier in attic.

In this moisture prone space you don t want water vapor from the ground drying to the inside of your home. Such a location works both as a vapor barrier as well as an air barrier and eliminates the need for an external air barrier not a easy application on a multi storried building as well as any special electrical pans and their sealing. It is important to note that air control is more important than vapor control. Do not add a vapor barrier on top of the insulation in your attic since the paper facing on the existing insulation is the vapor barrier.

I install my vapor barrier in the middle of the wall system between the two walls. In some cases the vapor barrier also acts as the primary material in the air barrier system. Moisture transport by air is significantly higher 100x than moisture transport by diffusion. Not every wall does.

Whether or not you need a vapor retarder hinges on three main factors. You have loose fill insulation in the attic which doesn t have a vapor barrier. For a chart of vapor retarders by climate zone see the naima s insulation and vapor retarders in crawl spaces install a class i vapor barrier such as a vinyl liner on walls and floor. Attic vapor barrier detail for cold climates the best approach for a vented attic in a cold climate is installing a layer of drywall with a good coat of latex paint the paint creates a semi permeable vapor barrier.

This is primarily due to the kerdi board or wedi. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. The theory is that part of the moisture vapor in the house is actually blocked by the drywall and paint on the. The vapor barrier does not need to be sealed to function adequately.

The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. Youll see that i mention roxul a lot in that tutorial but roxul is exactly the same as rockwool. Vapor barriers installed on the interior side of assemblies impede them from drying toward the interior this is a problem for air conditioned spaces and can be an issue when there is also a vapor impermeable material installed on the assembly s exterior creating a double vapor barrier wall assembly.