1986 winnebago Roof Structure - Is there any thing supporting roof?

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beautysmistress

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Jun 15, 2015
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Anchorage, Alaska
Ok so got no reply on what I might find when I pull the aluminum sheet off of the roof. So went ahead and ripped it off.
  I have found directly underneath the aluminum a type of sandwich made up of a top layer of plywood a mid layer of rigid insulation, then another layer of plywood. the plywood is all really thin.. maybe 1/8" thick for each layers.
  It all seems in good shape and I hate to pull it up but there is a sag in the very end.
The whole "sandwich" can't be more than 2" thick.
  Does anyone know what is supporting the roof?  Or does the sandwich have enough structural integrity to hold up without supports?
  Hate to tear up more just to find out how it is put together.
Thanks for any info.. especially from anyone who has ever disassembled one..
Would love to see a cross section drawing or diagram of how it is assembled.
  you all have a great day!
Flash
 
I can't speak directly to your '87 Winnie, but yes the basic construction is luan plywood sheets with a metal skin for waterproofing. There are probably a few wood cross members under there, but don't expect 2x6 or even 2x4. More like 1x2 and not many of them. It's designed to shed running water, not carry snow loads.
 
Hi Gary, thank you for the reply.  I will try to remember to post a few photos of the project so anyone else working on a 1986 will know whats in store.
  At this time I don't plan to pull up the panel "sandwiches" as they seem sound. But I am going to lay a new layer of luan over the whole top.
  Then I will have a nice smooth surface to stick the rubber roofing to.
Any suggestions for how to attach luan to roof panels? Should I staple or glue?  or maybe both?
  Thanks again
Flash
 
thanks.. just missing one vent and a skylight for the shower then I will have all the components. Now will start cleaning off the old caulking from all the edges. I think that will actually be what I'd consider the hardest most tedious part. then wait for a sunny 3 day weekend :)..crossing my fingers this will work out!
  thanks again.
 
If you have a flat roof, stretch a sight line across it and make sure the weight of the air conditioner hasn't created a sag in the middle of the roof.  If it does sag you'll have a puddle whenever you park level and it doesn't take much depth to flood the air conditioner pan and go through the roof cutout into the interior.

There's no way to re-arch the styrofoam sandwich, so you can either build up the center with additional plywood before you put down the luan or leave the sag in place and make a collar to raise the air conditioner above flood level.
 
If you have 18" recessed fluorescent light fixtures in your ceiling you can pull one down to see some of the roof construction.

When laying underlayment for a floor it is nailed every 6" in the centers and every 4" around the edges using ring shank nails to keep the nails from pulling out. Staples or smooth nails will not do a good job in holding it down.

If you glue it you will never be able to get it off. Personally I would glue and screw.
 
Thank you Frank and Lou. We don't have an air conditioner but I was wondering if there was a way to put a slight arch in the whole roof.  that seems a bit daunting though.
  The roof sags more at the back end of the RV especially where the ladder connects to the top of the roof. Maybe caused by all the weight when someone climbs up there?  without the aluminum sheeting the sandwich sags almost anywhere you walk on it unless your a light weight.
  There are no fixtures in the ceiling. all the lighting is just flush mounted. Still I am curious about the construction and might try to get a piece of the sandwich out... then again if the sandwich breaks I could be in a world of hurt trying to repair that or build a new one.
  In the past when I build thing,s screw and glue was the way to go with floors so will do as Lou suggested and use both. A waterproof floor adhesive was suggested to stick it down with. will see what I can find up here.
  Thanks for the input.  This is the biggest project I have taken on in a while. No turning back at this point :) :-*
 
 
 
The roof should be bearing on the walls. This is just food for thought, have you considered building a framed roof over what is left of the existing. You would gain a little height and room for more insulation but would have to come up with a trim detail where the new roof meets the wall. At least you would know your new roof would be load bearing for AC's ect.

Tom
 
Hi Tom,
  Yeap I did think about ripping it all off and doing a whole new roof with some added framing.. but I am short on time. Got visitors coming and need to get er done.
I have run into so many little problems kind of wishing I hadn't started the whole thing.. :-\    But I now have all the parts in and ready to roll this weekend :)
  Its times like this living in Alaska is a problem.. hard to get parts and shipping is outrageous.
have a great day
  Flash
 
Here is what it looks like at the back corner with aluminium off.  Put the first sheet of 3/8" plywood up and butted it to the end cap.  Will be an interesting detail to seal. the plywood will be a little higher than the back piece. Wish Me luck :)
 

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The plywood being higher than the end cap isn't a problem.  Having it the other way so the end cap is higher and creates a dam and traps water along the seam is what causes leaks.
 
so the new plywood raised the roof and I had to put new plywood "spacer" under the z flashing to lift it also. I am considering putting the 60 mill on top of the existing trim and partially down the sides. see drawing.
  anyone have any thoughs on this.  Should I just stick wit the original design and put it under the trim?
thanks for input
  flash
 

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