Does Roxul Need A Vapor Barrier In Attic

Sup 2 sup and the need to install a separate vapor barrier.

Does roxul need a vapor barrier in attic.

Roxul would be my choice for a batt insulation. And by the way if you re remodeling a shower and use rockwool with kerdi board or wedi s shower system there s no need for a vapor barrier. If your climate does not meet these conditions a vapor retarder like latex ceiling paint will work well for your house if you are in all other climates except the hot dry and hot humid. By the time you paint the drywall though you ve brought it into the class iii vapor retarder range between 1 and 10 perms and even less water vapor will diffuse through.

Not every wall does. Moisture transport by air is significantly higher 100x than moisture transport by diffusion. I ve read that i need to use a vapor barrier but i ve also read that vapor barriers can cause houses to be moldy or can cause rot inside the walls because the walls cannot dry out properly. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

The downsides are the higher cost per ft. It is important to note that air control is more important than vapor control. Whether or not you need a vapor retarder hinges on three main factors. I am in zone 4 right on the edge of zone 5 in long island ny.

The vapor barrier does not need to be sealed to function adequately. Seal the air leakage pathways. 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. This is primarily due to the kerdi board or wedi.

In this moisture prone space you don t want water vapor from the ground drying to the inside of your home. I am doing a complete renovation of my house right now and i ve chosen to insulate with roxul comfort batts. Provide greater r value per inch which can be important if you need to add r 19 in a 2 x 4 framed wall for example. No you don t need a vapor retarder class i or otherwise.

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.