Unlike the recent "Excluding Woodchucks" thread, I have a more normal exclusion scenario, as they are just tunneling beneath the under pinning and going up under my clients' house. I've never excluded groundhogs before, but am getting ready to give an estimate on it, and was wondering if you would normally go with something much heavier than 1/2" hardware cloth. I was considering using 2" x 4" galvanized welded wire. Was also curious if it should be installed deeper. I've had success with the 8" down and 16" out for excluding skunks, raccoon, etc., but was wondering what changes would I want to make for groundhogs. 16" down and 32" out... or is that overkill? Thanks for the help.

That's overkill. Going out is most important. Go down your 8". 1/2" hardware works.

Thanks. So go out more than my usual 16"... like 30" or so?

IMO hardware cloth is not heavy enough. I use 1x2 galvanized welded wire.
Usually go down 12" and out 12".

ditto opie28. 1/2" hardware is not heavy enough when the chucks and coon especially really want to get in they will rip through the 1/2" hardward. We use 16 gauge vinyl coated 1"x1" go down 8"-9" below grade and out 8"-12" and anchor securly to building. If other smaller animals are in the area we use 1/2"x1"galvanized. We have seen where clients didn't want to spend the money to have a professional install exclusions, so we advised on what and how to install and they went cheap on the wire and put in 1/2" hardware cloth and the woodchucks breeched the wire. If I had a chicken coop made using 1/2" hardware cloth I wouldn't trust it to keep coon out. Just my 1 cent.