I know a groundcloth is supposed to be slightly smaller than the tent. What else do I need to know about keeping rain out of the tent?

Recently had a virtual tent flood in a hard rain lasting about 3 hours. I think the mistake I made was pitching my tent on hard bare ground as opposed to leaves and pine needs (duff), which absorb water or prevent it from being splashed up onto the sides of the tent. Am I correct about that? There was no duff available.

Groundcloths protect you from wet ground but not from standing or flowing water as you will get in a hard rain. This is why many tarptents and the like come with bathtub floors. A bathtub floor is a waterproof ground cover that comes up around you several inches on all sides to protect you from this.

Short of getting a tarptent (or even better in terms of water protection, a hammock) the best thing you can do would be to set up somewhere that is higher than the surrounding ground. Ask yourself what would happen in this spot if a huge rain fell. Where would the puddles form? Where would the water flow from and to? Site selection is quite the art but it can make a bigger difference than what kind of gear you are using.

If it's raining hard enough for water to flow across the ground, it can run under your tent and pool between the tent and ground cloth. The ground cloth is even worse at absorbing water than the hard ground. In that situation, you're better off with no ground cloth or with it on the inside of the tent.

A ground cloth will not keep rain out of your tent.

A ground cloth can collect water.

A ground cloth needs a few drain holes.

I never ever use a ground cloth.

A ground cloth mostly keeps the bottom of your tent clean and might help prevent holes in it if its too thin.

When I was a lad a ground cloth was made of cloth, canvas.

Jim

Y'all lissen ta Ol' Jim. If'n ya wants a groundcloth use canvas. Heah?