I use the straw hay because it's a little softer making it more comfortable to lay on and nest in. It's also not poking them when they do so. And it's a lot easier for them to build a nest with the straw because it's more pliable.Did you use grass hay? I have grass hay in mine. I didn't put a floor in my duck house because when it gets warm out, I can take all the hay out, hose it out then let it dry out. My daughter put floors in hers. When she hoses it down, it stinks really bad.
If straw hay is better, i will get some. Couldn't hurt to make it thicker. I also put a bag of pine wood shavings in. It keeps it smelling good.