Hi
I have done that with an outdoor aviary for obvious reasons. Depending on what type of vermin you have and how much they want to get inside . Certainly couldn't do any harm though I'd recommend the 1 inch woven chicken wire .Much heavier gage wire and resists decay much longer. gary

I have long been an advocate of using hardware cloth to critterproof any structure on a floating foundation. 1/4" 23 ga. is a bit light though. I prefer 1/2" 18 ga. but you don't need it for the entire subfloor, just the perimiter, so with enough to cover your entire foundation, you could double the lighter wire for some added strength.

Lay it just under the edge of the foundation and out, about 18 - 24 inches and secure the outer edge firmly. We use timbers, laid over the outside edges, then fill in the space with gravel, but dirt is okay too. However, you shouldn't plant any heavy rooted shrubs over it, or the roots will eventually tear the wire apart.

Regardless of how you finish it, just keep in mind that the critters will always dig right at the base of whatever structure they are trying to get into or under. They don't know to back off and seek the outer edge, so as long as the perimiter is completely secured, it will be safe from all but the most ambitious long tunnelers, but moles generally aren't the problem for GH owners in any case. They eat worms and grubs. You presumably want to keep out mice and groundhogs?

Thanks for the feedback!

I was sort of thinking that the 23 ga. would be too light, but the guy was offering it for free so the price was right. The plus was that it was also "post-weld" galvanized so it should last longer than just steel. Plus he was going to give me enough to do the entire base of the greenhouse. Guess I better go ahead a plan on something a little heavier (and more expensive).

As for the wildlife I've seen chipmunks (cute so I let them stay), moles and a rat from time to time (a restuarant is about a block away and I think they stray when the menu is bad). I've never seen mice for what that's worth.

Thanks,
Don

I used doubled up chicken wire under my GH. It's cheap, just like me. Haven't had anything get in yet (that I know of).