I’m working on a project in a crawl space. Huge thanks to Malcom for advice in another thread on how I might add additional insulation.

However, I am now facing an issue before I get to that step. This crawl space has always smelled musty. There used to be a deck on the other side of the wall that was in rough shape and was poorly flashed. When we replaced the deck, we had to remove and replace some rotten sheathing. Everything is now properly flashed and there are no new problems with rot. Some sheathing that was damp but still had structural integrity was left in place to dry out when we did that deck project.

Fast forward a few years and I am working on a project on the inside of this wall. I removed the vapor barrier today (which was in rough shape and poorly attached) and can confirm that some of the sheathing smells very musty. It is very dry and rock solid. Anything that looks like mold rubs off like a fine powder when I touch it. It’s still smelly though.

What’s the best way to eliminate this smell before I put insulation back in and add the vapor barrier? Also, is it possible that the insulation is retaining the smell?