Is a continuous moisture retarder necessary?
Charles writes from Melrose, Massachusetts: “I have a 1926 colonial with attic but no wall insulation. I would like to blow insulation into the wall cavity, but have no practical way of adding a moisture barrier. The interior includes wood wainscoting, and I don’t want to remove all the wallpaper in order to add a paint or wallpaper vapor barrier. Will there be enough venting through the gaps in the sheathing to allow any moisture to escape? Will outside wall vents provide adequate venting? Or is a continuous moisture barrier necessary?” Answer: Owens Corning does not have a recommended product for your specific application since there is no way to guarantee the insulation won’t bridge in the wall leaving gaps. You can still blow the insulation into the wall but you might want to see if there is someone in your location that can scan your walls with an infrared camera once the wall is insulated. The biggest issue will be warm moist air leaking into the wall cavity from the interior dur
