Dog Poops and Pees in House When Left Alone?

Five months ago we rescued a Brittney Spaniel. He is about 3 years old. We have taught him a few commands, and potty trained him, but when we leave, even for an hour he poops in his crate. Once he even peed in the crate and it ruined the floors so the crate was moved into the garage until we can trust him.

I'm not sure how to fix the problem. It's not every time we go out, but it's often enough that I can't allow him in the house without anyone home. He even peed on the basement door once when I went into the basement for 5 minutes without him. I know it's a separation thing or a spite thing, but I can't have that in our house. Help!

By Chrissy G.