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Ugh wet wood in Bigfoot

AH_AK
Explorer
Explorer
I recently bought a 2003 Bigfoot 10.5. The interior is in excellent condition. Seems to have barely been used. Generator has 30 hours on it. I paid the local Bigfoot dealer to inspect it before I bought it. No mention of water damage. So I get it home and start cleaning it and getting into all the nooks and crannies (like I should have done before buying) and I find some problems on the back wall. The trim below the basement back hatch is rotted but dry (previous leak). The wood seems to still have some integrity. There is a small hole in the shell which I assumed was caused by the fold up steps banging the wall while driving, but now I am thinking it may have been punched on purpose as a drain. So I go to the battery compartment and feel the back wall. Squishy. Worse, this is where the jack is mounted. I poke through the vinyl covering and the wood is an oatmeal consistency and still wet. It rained the other day and it was previously stored indoors, so I am thinking I have an active leak on that back wall. Could be the jack mount, or the window, or any number of other penetrations on that wall. I feel overwhelmed at the moment, but it seems like this can be fixed without gutting the whole camper.

Here is what I am thinking:
1. Take off the jack (I have it up on stands at the moment). Take off the mounting plate and see if I can tell which screws are in bad wood.

2. If rot extends up into generator compartment. Remove the generator otherwise just remove the batteries.

3. Rip out all the rotten wood and replace with good wood.

4. Remove and reseal all perforations on the back wall. Should I do this first? My thinking is that this might help me narrow down the source and thus the likely extent of the damage.

Best case scenario is that the seal on the jack plate is the source and I have found the worst of it. Guess my โ€œawesome findโ€ for a first truck camper was not so awesome.

Would love to hear from anyone that has had a similar problem and remediated it .
41 REPLIES 41

AH_AK
Explorer
Explorer
HMS Beagle wrote:
You can reinstall the trim strip and the vinyl bulge for esthetics, just don't seal behind it or underneath it (or on top). It just traps water and guides it into the holes. Proof of this is the shaft of the screws being rusted, so you know water is going in there. The stripped screws are common, they overdrive a lot of them there and elsewhere, they are only going into the bottom shell most places.

The bomb proof fix is to fiberglass over the joint which carefully done could look fine. Remove the gel coat to a tight line just above and just below the bump (structurally you need more below the bump but aethetically you'd want it to be even), tab carefully inside that line, paint the stripe to match or a contrasting color. It already has a bump and trim all the way around. It would be more work but a little cleaner to cut off the upper shell overlap before tabbing, the tabbing could be narrower and the bump would be less thick.

If rescrewing instead, I'd go up to the next size screw so that the pilot hole cleaned the hole of dirt and old sealant, carefully - with a torque limiting driver - drive in the new screws, then remove them, coat them in 5200 or whatever, and drive them back. Other than the very front where wind might drive water up under it, the seam is unlikely to leak as gravity is very dependable. It is the screw holes that leak. I've thought about removing the screws, wedging the top away from the bottom slightly and cleaning out the seam then resealing it with 5200 prior to putting the screws back but it would be probably as much work as just glassing over it. Would maintain the factory look though.

It's too bad the factory doesn't tab the shells together on the inside prior to installing the interior. It's probably half a days work for one guy at that point and would make the product far better.


The gelcoat is in pretty bad shape around the fastener holes. That's what you get for having all those screws loaded in shear. I wonder how much load they actually see. I think over-drilling and upsizing the fasteners is the way to go.

I am really not concerned about maintaining the factory aesthetics. I am comfortable that if I ever sell this camper, it'll be to someone that appreciates the practicality of the mods.

As an alternative to fiberglass, I was thinking I could just use a high-end marine coating. Basically, I am thinking fill and the irregularities and holes with epoxy putty / bondo. Sand it. Drill more regularly spaced holes. Install SS screws with 5200 and seal the bottom lap with 5200. Then mask off a few inches above and below and apply the coating. I am thinking something bombproof like deck coats on a boat. Either match the color or accent as you mentioned. The coating would be the primary seal and the 5200 a secondary seal if the coating fails around the fasteners. It's be a weird look with painted over fasteners, but I wouldn't need to stress about the fiberglass disbonding from the shell. Also, coating application is easier than FG layup. I wonder if the marine world has a coating that would tolerate the flexing that might occur over the seam. I am thinking a truck-bed-liner style of material.

HMS_Beagle
Explorer
Explorer
You can reinstall the trim strip and the vinyl bulge for esthetics, just don't seal behind it or underneath it (or on top). It just traps water and guides it into the holes. Proof of this is the shaft of the screws being rusted, so you know water is going in there. The stripped screws are common, they overdrive a lot of them there and elsewhere, they are only going into the bottom shell most places.

The bomb proof fix is to fiberglass over the joint which carefully done could look fine. Remove the gel coat to a tight line just above and just below the bump (structurally you need more below the bump but aethetically you'd want it to be even), tab carefully inside that line, paint the stripe to match or a contrasting color. It already has a bump and trim all the way around. It would be more work but a little cleaner to cut off the upper shell overlap before tabbing, the tabbing could be narrower and the bump would be less thick.

If rescrewing instead, I'd go up to the next size screw so that the pilot hole cleaned the hole of dirt and old sealant, carefully - with a torque limiting driver - drive in the new screws, then remove them, coat them in 5200 or whatever, and drive them back. Other than the very front where wind might drive water up under it, the seam is unlikely to leak as gravity is very dependable. It is the screw holes that leak. I've thought about removing the screws, wedging the top away from the bottom slightly and cleaning out the seam then resealing it with 5200 prior to putting the screws back but it would be probably as much work as just glassing over it. Would maintain the factory look though.

It's too bad the factory doesn't tab the shells together on the inside prior to installing the interior. It's probably half a days work for one guy at that point and would make the product far better.
Bigfoot 10.4E, 2015 F350 6.7L DRW 2WD, Autoflex Ultra Air Ride rear suspension, Hellwig Bigwig sway bars front and rear

BurbMan
Explorer II
Explorer II
When I rebuilt the Lance I used 4" Eternabond tape to wrap every corner molding. It's a similar issue: where the two filon panels come together at the corner, the seam is overlapped with an extruded aluminum molding set into butyl tape and fastened with a zillion screws. I found that the 4" tape gives a good 3/4" of sealing surface to the sidewalls on either side of the corner and completely encapsulates everything underneath. Not a crisp looking as a factory corner, but 100% will never leak again.

AH_AK
Explorer
Explorer
adamis wrote:
I can't answer your question but as a fellow Bigfoot owner, I would ask that you please document your repair process as much as possible! You appear to be headed were few have been before and so your experience (and pictures) will be an invaluable resource to the rest of us that may oneday walk the same path. Also, might be a great resource to send back to Grant at Bigfoot. Maybe they already know of this issue and have change procedures but having this type of feedback is always invaluable.

Thanks in advance... Fellow Bigfoot Owner


I will try and document as I go. I need to streamline my documentation process. I usually just take videos in case I forget how something was installed when putting it back together. Usually I am just rambling to myself in the videos. Perhaps I will try and be more coherent and post links here.

One of the things I like about Bigfoot TCs is the community. There are some super-owners on this site (several have commented in this thread), that are DIY beasts and are very helpful. The worst thing for me is feeling alone and thinking I am going to make some terrible mistake and ruin my camper. I will try and help contribute to the community, even though my experience is fairly limited.

adamis
Nomad
Nomad
I can't answer your question but as a fellow Bigfoot owner, I would ask that you please document your repair process as much as possible! You appear to be headed were few have been before and so your experience (and pictures) will be an invaluable resource to the rest of us that may oneday walk the same path. Also, might be a great resource to send back to Grant at Bigfoot. Maybe they already know of this issue and have change procedures but having this type of feedback is always invaluable.

Thanks in advance... Fellow Bigfoot Owner

1999 F350 Dually with 7.3 Diesel
2000 Bigfoot 10.6 Camper

AH_AK
Explorer
Explorer
So the shell seal was definitely the source of my leak. I found all sorts of fun stuff under there. Missing fasteners (holes appeared filled by the butyl tape on backside). Did Bigfoot use gray butyl there, or was that part of a repair? About 1/3 of the fasteners didnโ€™t have purchase at all. Around my leaky corner the screws were nuked. Maybe 40% diameter remaining, all the threads corroded away. The butyl tape was โ€œnormalโ€ in most places, but then watery and oily in others. Never seen that before and not sure what caused it. Only a few fasteners were clean of corrosion, mostly towards the door (yay at least I have some dry spots). It looks like Bigfoot used a construction adhesive/sealant on the shell lap (beige colored) and the screws go into that stuff where there is not wood. That sealant appears to get rubbery and expand when it gets wet. It was bulging out of my leaky corner. I pulled some of it out while cleaning up the wet wood corner beam. Didnโ€™t know what it was. Now I know.

I am pretty committed at this point to replace the entire shell seam. I really donโ€™t want to use the crappy trim that it came with and I am not too worried about aesthetics. My thoughts are:
1. 316 stainless strip with countersunk holes and stainless screws bonded to shell with either 4200 or 4000UV (hopefully it is never coming off again).
2. Get it all cleaned up, install stainless screws, take it to the boat yard and have them glass the entire seam and finish with gel coat. This will look a little weird and cost more, but imagine that, a 1-piece shell. Throw a transom on there and mount a 30hp and sheโ€™ll be ready to go fishing.

If 1, I will fill the holes with thickened epoxy so that I donโ€™t need to worry about new holes lining up with the old ones.

Any other ideas for how to re-finish the shell seam?

AH_AK
Explorer
Explorer
HMS Beagle wrote:
If you have the fiberglassing skills, do that. I never like plyood embedded in fiberglass, it is just a time bomb, particularly if it has any screws driven in (which is usually the reason for it). A non-embedded plywood backing pad can at least dry if given a chance.

When you say center seal, do you mean the seal between top and bottom that runs all the way around? That can be an ingress point, particularly the way they sealed them at the factory. The top overlaps the bottom, so if left that way it would never leak. But then they put a piece of trim on it, drill a million holes drive in a miilion screws (which used to be steel but they do use SS now), then seal the trim top and bottom with a fillet of silicone. The last bit is the coup de grace - usually the top fillet, being exposed to more sun and weather fails first, allowing the bottom seal to collect a pool of water behind the trim, which has no place to go but through the aforementioned million holes with rusty screws. Would have been much better to let the water run out the bottom, sealing the top (though the top seal is useless after a year or two).

I think it is practically no possible to reseal the actual overlapping seam, but also not necessary. Pull the vinyl trim strip, remove all the screws, seal the threads themselves with a good marine grade caulk as you drive in new SS screws. Clean all the failed silicone off the top and bottom of the trim and do not replace it. All the trim does is hide the screw heads, it has no sealing function at all.


This is so helpful. All I can say is thank you so much and if you ever come to Anchorage, AK you are welcome to park your rig at my place up on the hillside.

HMS_Beagle
Explorer
Explorer
If you have the fiberglassing skills, do that. I never like plyood embedded in fiberglass, it is just a time bomb, particularly if it has any screws driven in (which is usually the reason for it). A non-embedded plywood backing pad can at least dry if given a chance.

When you say center seal, do you mean the seal between top and bottom that runs all the way around? That can be an ingress point, particularly the way they sealed them at the factory. The top overlaps the bottom, so if left that way it would never leak. But then they put a piece of trim on it, drill a million holes drive in a miilion screws (which used to be steel but they do use SS now), then seal the trim top and bottom with a fillet of silicone. The last bit is the coup de grace - usually the top fillet, being exposed to more sun and weather fails first, allowing the bottom seal to collect a pool of water behind the trim, which has no place to go but through the aforementioned million holes with rusty screws. Would have been much better to let the water run out the bottom, sealing the top (though the top seal is useless after a year or two).

I think it is practically no possible to reseal the actual overlapping seam, but also not necessary. Pull the vinyl trim strip, remove all the screws, seal the threads themselves with a good marine grade caulk as you drive in new SS screws. Clean all the failed silicone off the top and bottom of the trim and do not replace it. All the trim does is hide the screw heads, it has no sealing function at all.
Bigfoot 10.4E, 2015 F350 6.7L DRW 2WD, Autoflex Ultra Air Ride rear suspension, Hellwig Bigwig sway bars front and rear

AH_AK
Explorer
Explorer
Update: the source of my rear passenger side leak appears to have be the center seal. A lot of the silicone caulk on the bottom seam of the center seal is cracked/ separated. Probably not a big deal but at that exact location the top silicone seam was also separated which would allow water running down the exterior wall to go directly behind the seal.

Does anyone have a drawing/picture of the center seal construction? I was always told these seals rarely leak and that the source is almost alway something up higher, but I have checked higher up and it is bone dry. Seems like the screws on the center seal allow an easy entry point for water if it gets behind the cover. I really just want to open up that entire mod seal and look for rusty screws. Unsure how one would do that though. Anyone know?

Now the super depressing part. I found more wet luan on the passenger wall behind the kitchen counter. This will be very hard to replace without removing the cabinets/ oven. It seems pretty limited and only extends 4-5 inches up from the floor. It is wet, but I do not see any mold. I am thinking since I am resealing everything anyway, i might be able to run a big dehumidifier out there in the interim to get it all dried out. My thought is If it doesnโ€™t present a structural threat, there is only foam behind (which appears relatively impervious to water), and no mold present, then getting it dried out seems like an acceptable solution.

Tearing apart the kitchen seems like a bit more than I am willing to do at this time.

AH_AK
Explorer
Explorer
noteven wrote:
Can you source Azdel panels to use in place of plywood?


Would need to have them shipped to AK, so not really a great option for me.

AH_AK
Explorer
Explorer
pianotuna wrote:
AH_AK wrote:
I am going to install a soft start on the A/C and then use a 2.2kW portable generator modified to run on LP.


Power on propane is derated about 10 to 15%. I suggest jumping to a 2.8 kw portable such as the Champion 3400 inverter/generator with remote electric start.


The issue here is size. The Honda will bArely fit where I plan to store it. Really it just needs to run the 11,000Btu A/C. I know several people that have done this will the old 2000W honda and a soft start on the A/C to reduce the current surge when the compressor kicks on.

noteven
Explorer III
Explorer III
Can you source Azdel panels to use in place of plywood?

pianotuna
Nomad II
Nomad II
AH_AK wrote:
I am going to install a soft start on the A/C and then use a 2.2kW portable generator modified to run on LP.


Power on propane is derated about 10 to 15%. I suggest jumping to a 2.8 kw portable such as the Champion 3400 inverter/generator with remote electric start.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

AH_AK
Explorer
Explorer
HMS Beagle wrote:
Geo*Boy wrote:
Instead of plywood, use Coosa Composite for your repairs. Itโ€™s impervious to moisture.

Coosa board is not a very strong structural material. I'd suggest G10 fiberglass sheet. It is reasonably available in almost any thickness, consistent, strong, bonds well, will hold self tapping or tapped machine screws as well as aluminum, and will not rot.


I emailed Grant at Bigfoot to see what he thought. I was considering a hybrid option of a fiberglass laminate with a plywood core (ala Tolman skiff glass over plywood). Basically a plywood FRP sandwich panel. I could also just build up an FRP laminate to whatever thickness I want (G10 is pricey). I actually have access to a vacuum bag system at work. Epoxy and FG weave is relatively cheap. I usually do hand layup and vacuum bag to get a good fiber fraction. If I want to do a really thick section (many plies) it might make sense to do vacuum impregnation.

The other tricky bit is that I am going to have to splice two halves together to get it into position. Either that or I will need to cut out a section of the generator floor and then patch it after. I digress.

I might be overthinking this. I donโ€™t plan to reinstall the generator so I am going to leave the compartment open so I can easily inspect for water ingress. I am going to install a soft start on the A/C and then use a 2.2kW portable generator modified to run on LP.

Anyone want to buy a 2.5kW Onan LP generator with less than 50 hours?