Roof type - leaks

Both of the motorhomes in my signature have metal roofs. Had rubber roofs in previous motorhomes and much prefer having metal roofs for ease of maintenance.

The 1st thing I did when I purchased each one was to apply 4" wide Eternabond tape around the entire perimeter of the roof seams where the roof meets the sides and seams on the front and rear caps. I also apply Eternabond tape around all roof vents, skylights, antennae mounts, ladder, etc. Been using Eternabond on 8 different motorhomes for 20 years and never had a leak after applying this tape.

What ever kind of roof you get, maintenance is the most important. In a class C, look very carefully at the cab over, that is a common place for problems with a class C. Good luck with what ever you buy, just have fun!

No matter what type of roof you have there is the same number of cut outs for vents, AC's, skylights etc, this is where leaks occur. I have a 24 year out MH with a rubber roof(EPDM) it has never leaked through the membrane. I recaulk and inspect at least once a year and never had a roof leak. I have resealed most of my windows due to water leaks because butyl rubber tape dries out. I have seen MH's with FG roofs with a lot of water damage because caulking cracked and water got in. So I would be more concerned how the roof was maintained rather than the material the roof was made of.

Be aware, too, that there are multiple types of membranes that at first glance might seem to be rubber roofs. Besides actual rubber, one can have a TPO roof (which is longer lasting than rubber) or one or two other more proprietary membranes. The differences may be important when making repairs or getting appropriate sealants, as not all such materials are recommended for all flexible roof types.

Lazy Daze is probably the only Class C with a metal roof.

I loved the aluminum roof on my 37' motor-home. Never had to do anything to it. Reflected heat a lot better than a rubber roof too. I wish I had an aluminum roof on my present 5th wheel. I wouldn't have had to re-coat it this last spring.

Caulk becomes dry over time. Caulk made for rv or marine use is more uv resistant than household caulks.

Depending on who caulked it last will determine how long it will take to become dry. As said , dried caulk has cracks in it. It also feels more brittle than new caulk which expands and contracts with weather.

If i were buying a used rv, i would inspect and apply a fresh coat of proper rv roof caulk. That way you know what you have and its done correctly snd more important, with the correct caulk. Some people will use dollar store garbage to dress it up to sell it do it appears to be well maintained.
Inspect all seams on rv sides and cabover area as well.

I would be looking at a class c with a fiberglass cabover cap like the SS 2018 and up has. Cabovers are notorious leakers. That is why some people prefer a full fiberglass cabover thats smaller , only housing an entertainment center instead of a queen bed. Its also more aerodynamic and can drive better in crosswind conditions. See Coach House or Phoenix Cruiser type models. Coach House are molded fiberglass , less seams to deal with. A lot less.

The roof , flat surfaces, uses a self leveling caulk like Dicor. That works for the roof vents , tv antenna and plumbing vent as well. You have to use an rv cleaning product to prepare those seams prior to caulking. Dicor also makes a cleaner but you can use other products, ask for advice about that. A very important step is the prep.

On vertical seams many people use Proflex RV in ‘Brite White ‘ which does not yellow as ‘White ‘ does.
I have been using 3m 4200 or 4000 marine sealant on my rv and find it much easier to apply than the popular Proflex and it lasts longer regarding uv breakdown.
There are many ‘youtube’ videos and how to caulk a boat or rv. After you put down the bead of caulk, you can spray it with an alcohol base cleaner then smooth it over using your wet gloved finger. The caulk will not stick to the freshly sprayed cleaner and will wipe right off. The caulk will only remain on the dry surface which its already covering. That makes the job so much easier.

Good luck, hope this info helps,
Bob

You have the option of an RV-Armor Roof or something similar.

We had a 1988 Mallard, if I remember right, it had an aluminum roof.

I found fiberglass best over rubber and aluminium. But for a large spend - suggest the seller conduct internal presurized leak test and report any leaks.