Advice needs about roofing an RV I am considering.

[Mike Conte]

Advice needed!!

Hi. I am considering a 1975 Midas Mini 260 (GMC 350 cu. In.) that was pampered by the owner (a skillful mechanic) for 35 yrs.  But the gentleman passed away before he could finish replacing the roof after it was hit by a tree. He almost finished framing (2x3's laid flat) and bought a roll of aluminum. If I buy it should I...

1: try to finish it myself or hire a body shop that does a lot of RV work.

2: Does the aluminum need a plywood sub-deck? I have read "no" but I can't imagine it is strong enough. From my research it seems the aluminum and 3/8 plywood will weigh about 300 lbs each.

3: Should I go with plywood and a rubber membrane and sell the aluminum (or maybe save it and dream of building a teardrop).

 Also, I think the roof should be usable to carry (for example) a small boat (mine is about 65lbs) or other cargo. I am probably just a newbie who thinks he needs more space. The boat is not that important.Please comment. 

It will be my first RV and we will be retired empty-nesters wandering the US and Canada visiting far-flung friends.

Thanks,

Mike354

[Mike Conte]

Thanks again.  Your advice really helps me to make the decisions and now I think I will buy the unit and do the work myself.  The biggest problem might be the fact that I will have to work outdoors so I'd better be quick.

I will have many questions I am sure. I will buy the power shears. I am also tempted to put 1/8" luan or similar decking on before the aluminum.

A couple of questions now... First I secure the perimeter with screws and all of them are covered by a sealing product and the trim .

   Do they have to be aluminum screws?  Round head? Pre-drill the metal? What is the tar-like product called?

    Is there a need to secure the metal to the wooden framing? How?

I hope these 3 pictures are useful.

Thanks folks,

Mike

  

                                                                                                                     

[david craft]

the metal roof is more work than the rubber....no doubt. why would the industry change? to give you a better roof? lol. a brad nailer should be strong enough to staple this metal. i use a 1/4" x 3/4" long staple. be willing to trim metal and then finish trim because the length is pretty critical. 1" long #8 screws (steel sheet metal)should work well in 1/4" hex head or #2 pan head. awning rail on the passenger side and simple j rail on the drivers. termination bar on the ends. get at least 1/2" over the sides to staple. staple metal, get some 3/4" or better putty tape on the molding and then mount it good and straight with a screw every 3 feet. no need to predrill. then go back and put a screw in each hole. staple near the edge of metal so molding covers the staple and edge. trim excess and caulk if you wish though many coaches didnt bother.

[Mike Conte]

Hi David, thanks again.

I just found Dave Creu's blog where he raised the roof 10" and applied a liquid rubber coating. I am still planning to use the roll of aluminum because it is part of the purchase deal but what really caught me eye was the edges.  Instead of the metal channel/molding, (of which I would have to purchase at least 35 feet), it looks to me like the Externabond tape could be used over the side edges.  Can you comment on this.

Now to check if I got your advice strait,,,,The aluminum should be secured at the front under the cabover and stretched back strait. Rather than centering the sheet, I should leave 1" (?) overhang along one side so that I only have to trim the other side which will be about 6" of which I will cut off 5".  Then screw it to the top plate of the wall and then "brake" it with a rubber mallet. At this point, the answer to my first question comes into play.  Can I / should I forget using the metal molding and cover the roof edge and overhang with Externabond?

Oh yes, one more critically important question... Assuming the rafters are 2" (actual dimension) lumber. what is the correct spacing?  under the assumption that the anatomy of the roof will just be rafters, insulation board between frame members and the sheet aluminum.  I definitely want a roof that I can walk on.  Or is it recommended that I lay down a deck of plywood?  Thanks again

[Rich Thomas]

Hi Mike, Rich here, If you are wanting a roof you can walk on in my opinion, you will need to support it with a plywood base. Also eternabond is soft and again in my opinion will need some type of cover to protect it as well, be it aluminum angle or some type of plastic or as you noted the aluminum screw trim. I wonder if you could put down the eternabond and then cover it with Herculiner ( roll on truck bed liner) It can be built up to 1/8 " inch or so. maybe something you can experiment with and see how it looks. good luck 

[david craft]

tradtionally, the metal would break and then staples in the side, to be covered by molding, perforating the roof as little as possible. 7/16" osb or 3/8" ply for full walk on, then the metal would just break the extra distance to meet them original screw line. i have lots of extra old molding no longer used by the industry. find an old repair place whos got some surplus for a deal for molding. the rafters are 16" OC. mark wiring locations so you steer clear. are there no rafters existing? go 2x3 and taper the ends to 2x2 to get a crown and then sheet over that. is there any ceiling panels? if not i just build 8x8 foot sections with rafter and ceiling panels and hoist up to position. 1x2 on the edges and the 2x3 tapered in rafter position. finished 2x2 are 1 5/8" square...plan accordingly.

[Dave Creu]

Hi Mike, Dave here,

Rich T. and David C. are spot on. The edges of the roof really need to have some type of moulding to protect the joint. Here, you can use the  Eternabond Roofseal (35 mils thick)or the thicker commercial Roofseal Plus (65 mils thick) to cover the joint between the new roof, and the sides, then you'll screw down the moulding over the Eternabond. Since the EBond tapes are like a super-butyl, the screws will be sealed as they penetrate the EBond, providing a watertight seal.

The roof really should have a plywood base if you are going to ever expect the metal not to sag, pin-hole, and leak over time. I used 3/8" plywood, and recommend it over the 1/4". For an RV, it's the perfect blend of rigidity, strength against punctures, and weight.

You "could" use your roll of aluminum over 1/4" plywood, but I wouldn't dare walk on any area but the rafters. If you use the 3/8" ply and roll aluminum, you can either just prime the ply or leave it bare. BTW, you want to space the rafters so they fall on the wall studs below them. If you can't see where they should fall, just start at the rear and make the spacing 16 inches on center, from rafter to rafter.

Even if you chose to sell the aluminum and use 3/8" plywood with EPDM Coating's Liquid Rubber in white, you will still need the moulding.

I hope I covered everything. If not just shout back.

May all go well with your adventure!

Be safe,

Dave

[Rich Thomas]

Every time I read one of these threads I get the erg to go out and do something to improve my own RV. I hope it has the same effect for every one else. For you folks that are tackling projects like the one here that Mike is contemplating, my hat is off to you. Mike, I am sure just by the questions you are asking that you are worthy of the challenge that lays ahead of you with this project and, I think you are doing a great job of research and knowledge building before you take it on. My gut tells me it is more important to you than just a summer project; perhaps a physical token of a lost friend, a connection to hold on too. That's a good thing and a motivator. I hope you jump in and finish this project and have many memorable moments in it's use.