I am looking at galvanized lag bolts (for the ledger) and carriage bolts (for attaching the beam to the post) for a deck. I can't find "hot-dipped galvanized" bolts/lag screws only galvanized. Is there any difference between "hot-dipped galvanized" and products labeled "galvanized finish" or can I use "galvanized finish" bolts on my deck? Should I instead get the stainless steel variety?
I would recommend the stainless steel bolts. They cost more but are stronger and avoid the rusting and corrosion problems of steel bolts.
The thing I like best - the stainless steel lag bolts have sharper well defined threads which cut nicely into a properly pre-drilled pilot hole for a superior holding power. Hot dipped lag bolts tend to mush themselves into the wood and are far easier to strip out if over tightened.
It depends on what kind of zinc coating you mean. Your basic (cheapest) lag screw or bolt is "bright zinc" plated and will not withstand ACQ lumber. I believe the Triple Zinc used on say Simpson and USC structural connectors is a different process (galvanized). Even their fasteners are hot-dip galvanized or stainless steel.
You can find stainless lag bolts at any local Fastenal Industrial Store. I would never suggest Home Depot or Lowes for that matter when looking for structural fasteners.. MSC is another good supplier. Carriage bolts usage? try to find Zinc coated carriage bolts not the galvanized form, they tend to be Stronger and will last for years.