Using a magnet for deck inspections

I just finished the course on how to inspect decks and I noticed that the list of tools required includes a magnet. I don’t remember reading anywhere in the text about the use of the magnet. The only thing I can come up with is testing the fasteners to see if they are ferrous or non-ferrous…but what would be the benefit of that?

Ron Combs

Those are listed as Optional Deck Inspection Tools.

Moisture meter
magnet; and

A magnet in side a plastic bag is great for picking, up nails, screws etc.
Even works great on grass Turn bag inside out and you have the magnet and the screws are in the bag .

Check flashing to make sure it is not aluminum.

Hope that crazy deck guy doesn’t show up.

That makes sense. Thanks.