How do mold dogs find mold behind walls when they can’t actually see inside them? The answer comes down to scent detection, training and a systematic search process. Mold Dog Network’s dogs are trained to recognize mold-related target odors, while handlers guide them along accessible wall areas rather than letting them wander freely through a room. When the dog detects its trained odor, it gives a clear alert that the handler can mark and document. In this guide, MDN co-owner Caleb Jones explains how wall searches work, why furniture placement matters, what an alert means and why locating mold doesn’t require opening every wall first.