Will Insulation Help with Musty Smells? 

No, insulation only helps control temperature. Insulation might suffer from the same problems that cause musty smells in the first place. Water in your crawl space can actually damage the insulation, making it wet and inefficient. Over time, mold could form on your insulation and actually contribute to the musty smells in your home. Only proper crawl space solutions can completely prevent musty smells from building in your crawl space.