I have a 2004 22t. The camper is in very nice condition. I have noticed some swelling along the edge of the roof on the back side of the camper and a small soft spot at the front corner at the front cowling. It feels like the underlayment under the rubber roof is swelling. It runs from the the front corner town about half way the length of the camper. I have not noticed any leaks inside, the back wall feels sturdy. I have patched with eternabond and ran a strip of eternabond down the entire length of the camper on that back side. The swelling seems to be about 8-10 inches wide. i'm almost afraid to ask, but do I need to look at a full roof replacement? if so, how difficult is that replacement?

DH says you are probably ok for the time being with Externabond tape. However if you are handy consider replacing the roof in the spring/summer. You Tube had a tutorial on how to do this. Some HiLo owners have done this major repair. I have seen some companies that do a full roof replacement and give a life time warranty. The cost probably excedes the value of the HiLo.

How much could it cost?

You would have to call for a quote. It is so much a foot. Do a search for RV roof replacement companies.

We just replaced the entire roof of our 2002 3302s (33ft). I used eterna bond in several places about 7 years ago & it appeared the glue from it had chemical reaction with the aluminum roof because it turned all the aluminum into powder. We ended up using Crazy Seal (crazyseal.com) because it’s the only product that would go over aluminum & wood as I had to replace some of the rotted roofing plywood with new 1/8” plywood. It’s a great product I did the entire roof for under 2k. Lots of work but a great product they offer 50 year warranty

How difficult was it to replace the plywood? I have the rubber roof?

Thanks for the info. How did
You replace the plywood. Any pics