Check your roof for flat spots where you can have standing water.
With a flat roof water basically has no place to go hence peaked roofs with gutters and downspouts. If you could lift one side and seal all the others with walls think your problems would go away.
A good roofer can tell you how its done, course all the grunt work goes on under the roof,if you have the room. House I have now had no gutters nor downspouts. Walk out the door instant shower.
That lasted until I saved up enough money and a neighbor who did such work set things up. Back then it cost a couple grand.Which I thought was crazy, but my buddy who does good work high ladders humping up drainpipe and all the other stuff adds up. Frank