Sorry about your water leak. You have come to the right place for help on your Sunny and you come with the right attitude about fixing it and learning from this.
We have many of us who have gone through water damage repair and while there is no 2 repairs exactly the same, the common repair theme is the same.
Find the source or sources of water entry, remove all water damage, (don't stop short, it will come back later) fix it up and go have fund camping again.
Pictures really help us understand what you are up against and how to help give better suggestions. If you need help posting pics, let us know we can help with that too.
Since this is your first time into this, the unknown can be a bit overwhelming. But... don't despair, the way theses Sunnies are built, all is reparable and you can do it yourself if you have access to common wood working tools. We can help and glad to share our experiences on how things come apart and what to use to put them back together. The costs for materials can be low to moderate, the time to do the work can be high. Hopefully you can do the work yourself or have a friend who can help you that works well, real cheap... Apple pies have been known to do wonders
Here are some answers to your questions but we will need to know more about your leak situation. Odds are high, the source of water infiltration may not yet be known nor the amount of hidden damage you do not yet see. Once you start taking the camper apart, it will become apparent there is more to this. And you need to keep digging until you find the end of it.
This is where a lot of issues start. The sealant cracks over time, the owner does not realize they have to be after this at least least 4 times a year looking and patching when sealant splits just start. Then they can be patched and no damage comes. Left untouched, time goes by and 6 months to a year later it have been leaking. This post will help on the roof sealants.
Sealants for the corners and the windows.
See this post which may help on the types of sealing tapes. You really do not want "putty tape" and do not use silicone products on outside seals. Silicone is a good product, just not for the outside of the camper http://www.sunlineclub.com/forums/f7...ape-16936.html
Windows, corners and siding along with general rot repair.
You are going to need to keep digging to find all the rot and then repair the damage. This on going post is about roof replacement, but it shows a lot of that you will be up against. Including taking off the back wall of siding. The pics in here may be helpful to show you what you may be up against and how to repair it. There will be more added to this in the next few days about sealing the corners etc.
And lastly, here is a Goggle Custom search for our forum. Our Admin made this for us and it work a lot better then the embedded search feature of our forum software. Just type in water damage or rot etc and read on.
It is helpful to others and you if you can picture post your repair. This helps others like you in the future when this topic comes up.
Good luck and let us know if you need more
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
Google Custom Search For Sunline Owners Club