No assembly needed.  Rain resistance is good. As you can see in my photo the water beads up on back cushions and is slowly absorbed on bottom cushion covers if left on it for extended time.  Because the inner cushions are covered with non absorbent material the outter covers dry very quickly.  I was hesitant to purchase because of a few poor ratings by customers but glad that I did. My wife and I love this set. I’m 245 lbs and these cushions are comfortable and the set is plenty sturdy enough for myself and several others to sit on.  I just wish they could have shipped sooner than they did but I knew before purchasing that it would take 3 weeks for delivery and glad I decided to wait.