1988-1992 Chinook fiberglass roof repair

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Chinnin-about
Posts: 214
Joined: November 27th, 2017, 6:07 pm

1988-1992 Chinook fiberglass roof repair

Post by Chinnin-about »

I'm looking for roof drawings for a second generation Concourse (1988-1992). A previous owner drove under a carport ( or some other canopy) and hit the air conditioner, breaking the supports. They did a repair by adding two sheets of plywood and a membrane roof. On the interior, you can see the original fiberglass roof sagging two inches at the air conditioner, and in the cabinets. I would like to repair it properly, assuming the impact broke the horizontal wood supports. I'd like to locate them before I cut into it and repair it.

Thanks in advance.
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Blue~Go
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Joined: July 31st, 2014, 1:01 am
Location: 1999 Concourse

Re: 1988-1992 Chinook fiberglass roof repair

Post by Blue~Go »

Hi Chinnin,

Thanks for taking the time to re-post your query in the projects/issues sub-forum. I hope someone does have drawings, but... I have never seen any but the ones I posted (1999). I think the reason those are "out in the wild" is that back in the day, a prospective buyer had an idea for something they wanted to do on the roof, and so Trail Wagons sent them drawings back and forth discussing it, and those are the ones we have now. But, you never know. I'd sure like to see them if they exist.

On to your specific roof. I don't know how the roofs prior to around 1994 (Scott's year) were done. But I think his, and certainly my generation (1997+) were a cored fiberglass construction. No wood in the traditional "stick built" sense. Instead they used a technique that's often used on boats which is a sandwich type of construction. Two skins (of fiberglass in this case) are held apart by a core material*, with all three tightly bonded together. This makes a sort of "I-beam" and you can have a fairly large, fairly thin, horizontal surface that is still stiff (like, for example, a boat deck). If the layers are not tightly bonded (or the bond fails later), then things can become saggy (you then have three thin bendy layers instead of one, much stiffer "I-beam").

So I guess the first question is.... was yours made differently? I have never been in a Chinook older than 1997, but on the other hand, I have never seen roof "beams" in the traditional sense in any photos. On the other other hand, I'm not sure when they first started including roof air-conditioners, so maybe even before the "incident," a previous owner made some sort of wooden framing for adding one? Then later it was damaged and repaired (sounds like in a way that doesn't really go along with the benefits of the original fiberglass shell method).

How about some photos? That would help immensely.

BG

*This core material can be a number of things. It CAN be wood, but just not in the traditional "framing" sort of way. Common choices are foam, plastic (Nidacore, like in mine, which is sort of like a honeycomb of plastic), balsa wood sheets, or plywood. The important things are the thickness (the farther apart the upper and lower skin are the stronger) and the bonding ability (bond is key). Of course lighter is usually preferred as well (foam, balsa).
1999 Concourse
Chinnin-about
Posts: 214
Joined: November 27th, 2017, 6:07 pm

Re: 1988-1992 Chinook fiberglass roof repair

Post by Chinnin-about »

Thanks so much for your reply Blue~Go.

The Chinook is currently in getting the furnace fixed and all the other coach components tested, serviced and certified. I'll post pictures when it is back home.

I have talked to a couple of fiberglass shops, but I think I'm going to need to find a fiberglass guy who works from home, as shop rates here in the Northwest are 145 an hour. It's easy to see how such a project might push 40 hours, according to one bid I got. As you might imagine, there is a point of diminishing return on cost and the current system works well and has never leaked.

It also will probably be a fair weather project as well, which will include interior upgrades. I would probably be able to participate in such a scenario to keep costs down. Once I find someone who will work with me without needing to forfeit my right (or left) arm, I'll decide if it makes sense to proceed.

I'll keep you posted.
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