The grooves are long enough to reach out past the outer edges of the 4x4's. Although I didn't measure the grade, the slab is on a distinguishable slope. Yea I wasn't thrilled about the final construction quality on the prefab, but I don't have the time right now to build something. The roof pieces appear to be tar shingled, which I supplemented with premium grade outdoor silicone. The description also called the wood 'glazed pine', which wasn't glazed, or pine...lol. Appeared and smelled like cedar. Prior to assembly, I bought a gallon can of Olympic's best clear wood sealer, and treated everything. I also added the hasps and carabiners you see. At some point I'll have to build them a better coop, but this should do for now. There is a roof overhang over the coop, along with a rain gutter. In the event of a lot of wind/rain, I also drop that blue tarp, and stake it out in the yard (makes a large covered area). That pretty much keeps everything dry except for ground saturation