I was only given this to test raw lumber I bought from a lumber mill near my driveway. Worked exactly as it should, got it too when thinking about buying a 5 wheel camper or trailer and it will give me peace of mind that there are no leaks in the roof or walls . My only complaint is that it doesn't damage the surface as it uses 2 moisture measuring pins. I've seen other, more expensive, non-scratching ones that are better suited for RV use.