Having used this myself to fill in the cracks in a room full of paneling, I’d think it wouldn’t do well outdoors, because of it soaking up water. I know after reading the Jigstones site they only recommend it for items not going outside for that reason. the link to that part is http://www.jigstones.com/pages/story-casting-materials.html but as long as it’s brought in when ever there is going to be some rain I’d think it would do fine.