Drywall Repairs and Vapor Barriers
Repair of a vapor barrier. If a vapor barrier is damaged during a drywall installation or repair, it can be patched with tape, but small holes will have little effect on its effectiveness.
When repairing drywall on an outside wall, it is almost impossible not to damage it Vapor barrier. What can be done to ensure a vapor barrier is not broken?
– Levi Hymes via email
Martin Holladay: You don’t mention what type of vapor barrier it is, but I suspect you are referring to a layer of polyethylene. While air barriers need to be continuous and without holes to function effectively, vapor barriers don’t need to be hole-free. A vapor barrier littered with holes that make up 5% of the area of the vapor barrier is still 95% effective. Patch the polyethylene with Home wrapping tape if you can but don’t worry US building codes do not require an internal vapor barrier. In Climatic Zones 5 through 8 and Marine Zone 4, most U.S. building codes require an internal vapor barrier (a more permeable layer than a vapor barrier). The requirement for an internal vapor barrier can be met with a layer of vapor barrier paint.