This is a STURDY bed! We purchased it primarily because we don't have a lot f space in our guest room where my grandson naps. He is transitioning from the crib to the bed. He sleeps in the top and I feel very secure with him there. The stairs and rails are super!  There is a 175 lb rating for the top and a 200 lb rating for the bottom. I think that's based on the pine slats under each bed. I'm guessing there is a safety measure factored in and the beds, at least initially, could hold more weight. My husband put up 90% of the bed himself. He only needed my son's help lifting the bunk up. We are extremely pleased with the quality!