My garage is detached and I have noticed that there is water damage to the outside trim and walls. The trim comes off in my hand and I can squeeze the water out of it and the walls are soft in some spots and mushy. There are no gutters. I think there are at least three roofs and there is moss growing in some areas where the water comes over the edge. I have been in my home for 21 years and there was never any gutters on the garage. Should I use the services of an inspector to find out if I need to replace the garage or the side of the garage with the water problem and should I put up gutters? There doesn't appear to be any water damage on the interior.

I wouldn't go to the trouble of having an inspector out. It's pretty obvious that you need a new roof and the siding repaired & replaced. I would just check with neighbors and see if they have a contractor they would recommend. If you have to take potluck, start with the local homebuilders association for references and cross check with your Better Business Bureau. Be sure to get at least 3 estimates IN WRITING. Good luck!