73 D18 roof replacement

[demon]

for now im not putting anything up there until I finish the rest of the Winnebago . then i can figure out exactly where things will go but only plan on having the ac and maybe 2 vents. What I still dont understand is how come it was never a problem from the factory? the aluminum was glued down to 1/8 wood. the aluminum on the roof is flat . the aluminum on the sides has ribs in it so i can see that would help there but the roof was perfectly flat aluminum.

[TerryH]

Aluminum, and I have worked together in various forms for more years than I will admit. It has one of the highest expansion/contraction factors of any surfacing you are considering.
When one substrate expands/contracts at a factor of .001 and the substrate it is 'bonded to'  expands at a factor of .010, (factors are abstract) something has to give. Physics, metallurgy, chemical, weather, temp variations, they all enter and with differing factors.

Not saying it is a huge consideration here, but should be part of your decision.

Should you have a commercial building in your area that is clad with aluminum - fairly common - stand in front of a wall as the sun hits it. You will actually hear 'cracking, popping sounds' as it expands.

As for 'where would it go?'. It will follow the path of least resistance. Should it meet something with greater resistance it will start expanding elsewhere - against your adhesive or whatever lets go first.

Again, take into consideration the amount of new roofing you have removed for vents, AC, etc. Both the reduction in roofing square footage and the various cut outs and that they are variously placed works in your favor.

[Rickf1985]

EDPM, The easiest and most user friendly way to go. And since you are starting over a brand new surface it is ideal. You can get different thickness's but it is a lot tougher than most people think it is. Unless you hit it with something sharp it will stand up to most anything. The thin aluminum is not as tough as far as I am concerned. And if it does get cut then repairing it is simple, repairing the aluminum means gooping mastic on there and we all know how that ends.

Fiberglass is alright but you are talking a huge area, Have you figured the cost let alone how are you going to lay up an area that size without having resin hardening issues? I figure a couple gallons of resin? You could have a rubber roof on before you got the first layup done.

Here is a site for glass and supplies and a lot of good info. I am going to save this one myself.

http://www.fiberglasssite.com/fiberglass-videos-1/

[demon]

man I hear what your saying but just cant see that happening. The original roof goes around the edge and down the wall about an inch and then stapled then the rain gutter pieces were screwed on to the sides. If it expanded an inch  where would it go? it was all glued down. Now im back to thinking fiberglass..

[Rickf1985]

Trailers are all aluminum so they expand and contract at about the same rate, you are talking aluminum over insulated wood. I am not saying it will happen, I just know 20 feet of aluminum will grow about an inch in length if I remember correctly. What are you going to have at the edges to cover the edges? You will probably have an overlap molding there so that will keep the sides attached plus any vents and stuff on top plus whatever moldings you have front and rear so I guess the glue will hold with all that other stuff to keep things in place also.

[demon]

also was thinking if the aluminum was riveted like a tractor trailer and it  expanded and contracted you would think it would leak all around the rivets ? The contact cement is rubbery so it would give i would think

[demon]

Not sure . Either .032 or .040 but I havent got it yet. Not sure about what was on there either. I didnt measure it

[Rickf1985]

How thick is your metal?

[demon]

Intersting! I went back out and looked at the old metal and it was definatly glued to a thin piece of wood and then the foam and,another piece of wood on the inside. I'm,guessing that's the " thermobond " they are talking about. The walls are done the same. There is no way they are not glued with something

[Rickf1985]

Aluminum expands and contracts a LOT in the heat and cold so I don't think gluing it down is a good idea. IF the glue did hold then something has to move with the expansion and contraction, that would be the roof structure or the metal buckling. That is probably why that did not glue the factory metal roofs and instead just put molding over the edges, so it had room to move in and out. (and cause leaks W% W% )

[CapnDirk]

on the aluminum roofs I've done, it was not bonded down.  It was centered then all the vents, AC, whateva held it down.  The front and rear edges got incorporated with front and rear skins or whatever, and the long edges with whatever trim was up there with a slight rollover of the top skin.  Most motorhomes you will see a trim piece up there.  Mine....well.... they decided to put a glued down quarter round piece of aluminum.  We all wound up with leaks.

[Rickf1985]

Vinyl is flexible, I am not sure you would get the coverage needed on the metal.

[demon]

Ok , I think I found the aluminum to cover the roof but I havent got it yet.Ive been looking online  I was thinking of using contact cement to glue it down. Thats what they use on vinyl tops on cars and it holds well. Any thoughts?

[CapnDirk]

Another thing is a roofing STAPLER.  It's what I believe they used for making the cabinets (where they would bridge the joint on a 1X2).  1/2 crown stapler was popular for crating and fencing (of course use non corroding staples on fence).

[legomybago]

I have a 7/16" crown stapler I use for sub flooring, fence boards, cement board (tile) flooring, it would work great for this application.

[demon]

yea i just have a harbor fright air stapler I bought to build my wifes chicken coop.  They are narrow staples probably 3/4" long. Your probably right, wider would be better but it will be ok. Is glued down with that construction adhesive you guys talked about in the beginning and also the the roof top whether it ends up being fiberglass or aluminum,  will wrap around the sides at the top and get stapled  thru the side at the top than the aluminum drip rails get screwed on thru the side wall aluminum and the roof skin. Not likely to will come off!

[Rickf1985]

I went back through all of your posts and I don't see any mention of what kind of stapler you are using? All I can find are the 1/4" crown staples and they are way to narrow, I would love to find what they used when they built these hings but hen finding the staples to go in it could be a problem.

[demon]

Roof is glued down and stapled!!! No pics cause it looks just like it did in the last pics. Now to decide what im covering it with.

[demon]

I was afraid to run strips of wood down the sides on top of the sides then try to attach the rafters to that piece right at the tip of the rafter. Its only 3/4" thick . what we did was set the rafters all the way to the aluminum so its sitting on top of the wall then we used that nice 3/4" plywood and cut pieces to fit between the rafters on top of the wall. then the 1/4" plywood is on top of all that right to the aluminum so that connects everything... everything is glued and stapled. heres a pic where you can see the wood on top of the walls

[Rickf1985]

So this whole roof is not attached to the rest of the unit yet? I hope that does not come back to bite you after all of this hard work! I would have anchored the ridge board to the walls and then the rafters to that and built up from there to tie everything together. As long as you are using something along the lines of PL2000 construction adhesive when you glue it down you should be good. I am old school and just don't trust staples and glue although today's glues are stronger than most nails. Hm?

[CapnDirk]

That's why I was asking.  Looks like it might have some character with a little light stain and sealer.

[demon]

Its raw wood...called utility panel??? thats what the tag said above it at the store.I really like the way it looks. im still not sure what the whole interior is gonna be exactly so this might be covered anyway but I might just use some kinda sealer on it...we'll see

[CapnDirk]

is that raw wood or paneling?

[M & J]

 

[demon]

One last pic of the ceiling