Does Roxul Need A Vapor Barrier In Attic

Moisture transport by air is significantly higher 100x than moisture transport by diffusion.

Does roxul need a vapor barrier in attic. Not every wall does. No you don t need a vapor retarder class i or otherwise. The vapor barrier does not need to be sealed to function adequately. 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.

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. Roxul would be my choice for a batt insulation. I am in zone 4 right on the edge of zone 5 in long island ny. I am doing a complete renovation of my house right now and i ve chosen to insulate with roxul comfort batts.

In some cases the vapor barrier also acts as the primary material in the air barrier system. A plastic vapor barrier is best installed in a vented attic within climates with over 8 000 heating degree days. It is important to note that air control is more important than vapor control. 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.

Seal the air leakage pathways. Whether or not you need a vapor retarder hinges on three main factors. 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. 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.

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. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. In this moisture prone space you don t want water vapor from the ground drying to the inside of your home.

Youll see that i mention roxul a lot in that tutorial but roxul is exactly the same as rockwool. Sup 2 sup and the need to install a separate vapor barrier.