Bigfoot with interior roof damage....

[Ken Vernon]

Hello,
I have a 1987 19' Bigfoot that has some water damage in the roof area. This trailer has A/C and some water has made it past and into the space between the fiberglass and the interior roof paneling. The exterior fiberglass roof ahead if the A/C has flattened out some, due to the water and I think a heavy snow load.

I would like to know what I will find underneath the interior roof paneling. I know there is foam, but will I find some wooden struts that run side to side or front to back or what? How is the interior paneling held up? What kind of reinforcing will I find around the 12"x12" roof/A/C vent hole?

NOTE: The fiberglass outer shell is flattened out but there is no cracks. I hope to pull the paneling dawn, modify/fix/replace struts or something to bring the shape back to or close to normal.

Any thoughts?
Ideas?
Been there done that?

Otherwise the trailer is in awesome shape. Its absolutely worth some time and effort....

Thanks for reading


Ken
(A new and excited Bigfoot owner)
CANADA

[Frederick L. Simson]

I would like to know what I will find underneath the interior roof paneling. I know there is foam, [b]but will I find some wooden struts that run side to side or front to back or what? How is the interior paneling held up? What kind of reinforcing will I find around the 12"x12" roof/A/C vent hole?

"I am not a BigFoot owner, but I've seen them on the Internet"
[b]Molded Fiberglass construction is totally different from all other methods.
No "Struts", No Joists, No Rafters, No Body Frame of any kind. Think: Unibody...

The reason we call conventionally constructed trailers "Stickies" is that they are made of "Stick" frames, covered in inner and outer skins. Without the frames, "Stickie" trailers would collapse. Molded Fiberglass trailers are called "Eggs" because the entire structure is in the Shell, and it stands on it's own without any framework. How is the interior paneling held up? In a word: adhesive. Everything on the interior surface is supported by the Fiberglass Shell.
Additionally, the built-in furniture takes on a more supporting role, acting as partial framing across some interior spans.

I have found a link to a picture of a BigFoot Owner's cross-section of his roof construction:
Bill Abbay's Signature Link Scroll down to the 5th photo, under "More Odds and Ends..." It is a photo of the roof AC/vent hole.

[Mike Magee]

"I am not a BigFoot owner, but I've seen them on the Internet"
[b]Molded Fiberglass construction is totally different from all other methods.
No "Struts", No Joists, No Rafters, No Body Frame of any kind. Think: Unibody...

The reason we call conventionally constructed trailers "Stickies" is that they are made of "Stick" frames, covered in inner and outer skins. Without the frames, "Stickie" trailers would collapse. Molded Fiberglass trailers are called "Eggs" because the entire structure is in the Shell, and it stands on it's own without any framework. How is the interior paneling held up? In a word: adhesive. Everything on the interior surface is supported by the Fiberglass Shell.
Additionally, the built-in furniture takes on a more supporting role, acting as partial framing across some interior spans.

I have found a link to a picture of a BigFoot Owner's cross-section of his roof construction:
Bill Abbay's Signature Link Scroll down to the 5th photo, under "More Odds and Ends..." It is a photo of the roof AC/vent hole.

After looking at the roof cross-section photo you referenced, I'm surprised and a bit perplexed. This looks a lot like "stick construction" to me. This roof does not appear capable of "standing on its own" without the wood to support it. When a builder puts in a pair of plywood sheets with something fastened in between, the whole is stronger than the plywood pieces alone... is that not a sort of joist (functionally speaking)? Or at least a partial wood "frame"?

The OP was concerned about finding "wooden struts" between the roof and ceiling... he will find plywood instead, and that doesn't seem much better to me because plywood can mold and rot, too. The reason I'm buying an egg is partly to get away from what stick trailers have: wood in the ceiling and walls that can mold & rot. If Bigfoot trailers need this sort of roof support, are they a true egg? Are the top and sides molded as one piece? If so, I'm speculating that it must be pretty thin FG if it needs all that plywood.

Also, since Ken's roof has a flattening (sag?) in it, I wonder if there may be damage to that wood already on his unit. Plainly his FG roof isn't "standing on its own" very well.

[Ken Vernon]

Thanks for the input.

Its raining here today, but I took a screwdriver out to the trailer and removed the A/C cover in the inside of the trailer.

I can see a few small sections of the roofs cross section. It looks, from what I can tell, like the cross section of Bill Abbay's newer Bigfoot. Having said that I can't see allot to be certain.

Thanks again for the input, I really appreciate it. If I get a chance to remove the A/C unit all together, I will know whats going on up there and I will post a few snaps...

Thanks


Ken
CANADA

[Roger H]

Another Bigfoot owner here... first you've got a twenty-one year old trailer, and it sounds like the caulk in the through-hulls on the roof wasn't kept up. The problem isn't so much one of design as one of maintenance. "Stickys" not only have through-hulls to maintain, but tons of seams to leak also. That's where a fiberglass rv has the advantage.

And, Mike's right... all fiberglass rv's use some sort of interior structure to support the roof... on the smaller ones it's typically the cabinetry and maybe a support of some type on the other side. Larger ones like the Bigfoot need the trusses to support the weight of that huge roof. The early Boler 13s had flat roofs and no supports... and even they sagged very quickly and got a differently designed roof for the third production year (or thereabouts anyway).

Bigfoot has changed their trailers significantly over the years. The older ones ('87) had a very flat roof. They use some structural bridging across the roof because of the size of the expanse of unsupported glass. The newer ones have a slight curve up which strengthens the structure and doesn't let water pool like the flat roofs did.

As in the photos you saw, you'll need to replace those struts that have rotted to bring the support strength back to the roof, and your trailer will be good for just about forever as long as you maintain the seals around the through-hulls in the roof.

Good luck!

Roger

[Ken Vernon]

Hello Roger,

Thanks for the reply.

My 87 19' has a roof that crowns in the middle. I'll guess it 3" higher in the middle.

So, from what you said if it crowns then there will be NO cross members? Just laminated plywood?

Thanks

Ken

[Roger H]

No, Ken... I think you'll find... well for lack of a better word... rafters? stringers? I dunno... wood pieces cut to shape that span the roof anyway.

Roger

[Lainey]

I think you'll find... well for lack of a better word... rafters? stringers?

"Strapping" would be my word for this wood. Non-structural, but does add to the support the roof. I think it mainly serves to add support around openings (roof vents for example) and to give a hard surface for the interior panelling to adhere to rather than having to fix the panelling through the shell.

[Maureen M.]

Hi everyone. I too have a 1987 Bigfoot. My trailer is the F20 Fifth Wheel. I installed two items into the trailer earlier this summer and can tell you what I found on my era trailer. Since a photo is worth a thousand words, and I happen to have the "left-overs" from both a Fantastic Fan install and a Coleman Polar Cub 9,000 BTU Air Conditioner (both 14" square openings) I have attached a photo showing the cross section.



For the fan install, part of the hole cut-out was where the TV Antenna mount was located. We usually don't watch over the air TV when camping and the antenna was leaking through the crank shaft, so I used that hole as my pilot hole and mounted the fan. This gave me the air circulation I was looking for when boon docking on 12 volt or solar. Where the antenna mounted to the trailer instead of the approximately 1" Styrofoam there was approximately 1 inch of laminated plywood. This large block gave the antenna a stronger surface to attach to the exterior antenna and help prevent the fiberglass from cracking when the antenna was raised.

When I installed the AC unit, I too was concerned with the weight of the AC unit on the roof. Before I cut any holes into the roof, I used an electronic stud finder to "see" through the ceiling to locate any "studs" (strapping, rafters or whatever the official term is). I found one cross member that happened to be just above the ceiling panel molding that was right next to the potential opening. When I cut the hole, I carved out enough Styrofoam to insert a wooden frame. According to the installation instructions this was needed to add strength and prevent compression of the air conditioner mount. This also gave me the opportunity to look closely at the "stud". Sorry, I did not get a photo of that. Picture a 1" x 1" piece of lumber with thin cuts perpendicularly across the length of the wood every 1 inch. Each cut goes approximately 3/4" deep. By making all those cuts the stud is rigid and flexible at the same time. When the contact cement or resin is sticky and everything is bonded together the shape can be formed. Once everything dries (cures) the roof is quite strong.

Ken, if you are planning to remove the interior roof paneling, it's very much attached to the foam. That is, I think you would end up damaging the Styrofoam if you are thinking about removing paneling. The paneling also adds rigidity to the roof. Instead, I would keep the paneling, but first fix the leak and reseal around the AC. I've seen other posts where people used graduating supports to counteract the sagging roof. You should find some 1" x 1" framing around the AC vent hole, so that may need some attention. If you can do those things, and paint over any discoloration of the paneling, that would probably be your best bet structurally.

Hope that helps.
Chris

[Roger C H]

I was surprised to see wood in the roof construction. Pray that they used marine grade that doesn't delaminate in moisture. I would try drying it out first. Use a hair dryer and heat the area around the hole. This should be done inside to prevent any more rain from getting on the components.

Slight delamination might be repaired by forcing some slow drying, waterproof wood adhesive into the laminations, (through small horizontal holes if needs be), clamping the whole thing snugly and letting it dry. You might have to shape some clamping pads to retain the curve of the roof. The foam insulation may give you problems here by compressing.

If it has delaminated badly, I would think there is nothing to be done but remove it. Have you considered calling the factory?

Anyway, after all is replaced, I would surely SEAL the edges of the plywood around this hole, also any other holes in the roof and run TWO beads of caulk around the hole under the mounting flange. Also seal all fasteners and their holes.

I did read somewhere that silicone is not compatable with FG and that acrylic caulking should be used unlike the drain hole example shown in the link.

Just some thoughts. I am in no way knowledgable about this kind of thing. So the first thing I would do is find someone who is to l k at it.

Let us know how it works out for you.

[Roger H]

I was surprised to see wood in the roof construction.

This seems to be a common thread of thought in this thread. Folks... to set the record straight... wood and wood products are used extensively in the structure of fiberglass trailers. Don't be shocked. Roofs are commonly reinforced with wood strips especially in trailers with roof AC. If your table mounts to a wall, there is a wood strip fiberglassed in that the hinges attach to. Everywhere there's a screw that screws into the wall, there is wood glassed behind it for the screw to "bite".

Very few fiberglass trailers (if any) don't use any wood in their construction.

Roger

[Ken Vernon]

Good morning everyone..

Thanks so much for the input, I really appreciate it.

When I first posted my question/problem, I also sent an email to "Bigfoot" HQ in BC Canada. I asked only about roof construction and didn't get into my specific problem, this is what they sent...

"Hello Ken,
It sounds like the B-19 tandem axel. It's construction is the same as
today. The solid lock foam is bonded into the molded top section of the
trailer. There are no joist at all. If water intrusion has occurred at a
vent area, then it will be contained to that area, and will not migrate
like it would if it had a joist system.
Mark"

So, there seems to be a bit of discrepancy in construction and materials. I'm thinking, over the years the construction techniques varied/changed some. The addition of plywood as shown in Bills cross section on the newest models --------------->> struts/brace added in the late 80's early 90's -------------->> to no wood or struts on the older smaller models.

To sum up:

I think with the 1980+ years interior roof panel is bonded to the foam insulation and probably brad nailed along the edges and where they my be a strut.

My water damage is probably limited to just the interior roof panel.

My problems are mostly cosmetic.

I think to tare down and rebuild goes farther than needs to be done.


Thanks to all for the help, It helped me through the process of how to do, what to do and do I do anything at all.


Thanks


Ken

[Tim Wood]

I had a 93 17cb Bigfoot, and it had a leak at the TV antennae. My roof looked like the one in Chris's picture, almost like a luan for the ceiling. With marine material glued to the wood. To this day when I buy a trailer if it has a TV antennae I take it out and either epoxy up the holes or glass it. As someone pointed out here you do have to check these things out on the roof, windows etc. yearly I think. With my trailer I just purchased a 91 horizon, I have a leak around the fan that I'm dealing with now. But when I get it done it will be right. Tim

[TonyB]

Our 1989 B19 Bigfoot has air, the roof is slightly crowned in the AC area and flat fore and aft of it. I have been advised to support the roof in winter here in Canada from inside as snow load can be a problem.I will attempt to attach a picture. The only problem that we have had with water leaks has been from the attachment of the awning, probably not by the factory. I epoxied new wood backing blocks in place.