Leak in my coop roof

[Country4ever]

We had our coop built a little over 6 years ago. It was a 10x16 shed, to which I added 5 slider windows, a divider wall so I'd have a storage area, a steel entrance door and a ridge vent for good ventilation. (By "I" I mean the builder. (and I use the term "builder" very loosely!!)

This guy was recommended to me by 2 local hardware stores. But he did a really poor job. I guess he was too busy trying to convert me to pay attention to his work. The windows leak, the roof leaks, and the overhead trusses weren't adequately stabilized, the door didn't close and the one end wall bowed outward. So I had to pay another guy to come in and fix everything. I just didn't want to deal with the first guy again.
Anyhow.........the roof has leaked in a couple spots since the beginning. Its very close to the ridge vent, so we figured it was that. DH has caulked all around the ridge vent almost every Fall, but sometimes it still leaks.
Now the OSB board on the ceiling is getting very soft in 2 areas.
Outside, the shingles look okay. Any ideas on how to approach this?
We're not construction people, so we're sort of ignorant about what to do.
I'd prefer not to pay a roofer to come, thinking maybe we could fix this ourselves.
I know roof leaks are notoriously hard to figure out at times. Any tips/advice on how to handle this before we have holes in our ceiling? Anything I should be looking for that would give us a clue as to what's leaking?
Thanks!

 

[awtandrocks]

one thing you could do is just re-roof it with solid roof panels in either corrugated plastic or metal. These are really simple to install even for a beginner and as long as you use the proper fasteners (roof screws with rubber washers) it is pretty foolproof for leaks.

 

[spottedtail]

Yes, it can be hard to tell exactly where a roof leak is coming from.
If that was my situation, I would strip off those shingles and re-shingle it.
10 x 16 is a small job really.
After the old shingles are off, I'd take off the ridge vent, patch up the hole with plywood, and shingle over it. Vent through the eaves instead if you can.

As far as not being construction people, you don't have to be!
Just pickup a book at the library or local building center, or do an internet search. Shingling is actually easy and requires only basic tools.

BTW...Don't forget to take pics to the two hardware stores to show them the "quality work" their recommended man did.

Good luck,
spot