Bigfoot Wall repairs - Fiberglass RV

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Old 04-09-2019, 11:33 PM   #1
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Timwiltshire's Avatar
Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 27
Bigfoot Wall repairs

I bought my Bigfoot trailer in a rush. I'd had my eye on Bigfoots ever since I started looking into trailers for my wife and I. Everything about them made sense, especially in regards to the 2 piece fiberglass shell. I thought them to be leak proof. The fact that every single time one came up for sale on the island it sold within a day reaffirmed that idea in my head. So when I finally got to a 1994 Bigfoot 17' before any other prospective buyers did, I looked at the condition of the gel coat, frame, windows and fridge, and I looked for anything that was staring me in the face as wrong.

I was ignorantly blissful with my rose coloured glasses on. I bought the trailer for full asking price not knowing what I was walking into. I didn't know trailers well then, I didn't know what to look for. I certainly do now.

Our first camping trip just so happened to be in the rainy season, that's when I was tipped off to the potential rot in my Bigfoot. All the windows were dripping. I thought it was condensation, but it was leaking. I found a soft spot on the floor near the front dinette that was conveniently covered by a floor mat. Then I noticed some shabby wall paneling that didn't match the rest of the trailer, and during our camping trip I started to poke around. I found squishy wet doorskin all around the front end of the trailer. My heart sank. I'd bought a basket case.

I fixed it.

If you're there now, despair no more, look no further, here's a handy guide to help you fix your walls (floors in another post)

First, find those leaks:

Remove the affected windows. The windows pull off by removing the screws from the inner flange, then pulling out the inner flange, then going to the outside of the window and (with a plastic prybar, not metal) pry the window off the trailer. You may need to work your plastic prybar around the entire perimeter of the window before it wants to pop off, especially if it has butyl tape. Mine didn't, they just had foam tape which is why they leaked.

For now, run a strip of butyl tape around your open window holes, then stick a piece of clear plastic (6mil poly is ideal) to the butyl tape to create a sealed temporary window. This temporary window will be needed to keep the interior of your trailer dry and warm while you're taking the trailer walls apart.

The interior repairs:

I started the interior by taking everything apart. I did my walls in one go, and my floors in another. This post is about the walls.

The walls:

I had to take out the front dinette, and the forward upper cabinet to access the rotten walls.

I removed the table. This just literally unhooks from the walls. Stash it in your garage or somewhere dry outside of the trailer.

The front dinette seats act as storage from the outside compartment doors, the outsides and insides are skinned in 1/8" plywood and the framing is 3/4" x 1" solid wood. The seat top is 1/2" plywood and a piano hinge. Remove the seat top as a single assembly. There should just be some screws on the outboard most side of the seat holding the whole thing onto the framework. Remove the inner 1/8" plywood pieces with a prybar and a delicate hand. They're just tacked on with Brad nails so they should pop off fairly easily. Label the pieces and the frame as you remove them for easy reassembly. You'll now see screws going through the wooden framework of the dinette seat into the floor and walls. Use your impact driver (or drill or screwdriver) to unwind them all. Label everything as you take it apart. Stash everything outside of the trailer.

Next comes the upper cabinet. It's a real bugger to pull off and I ended up needing to remove the 1/8" plywood from the inside and outside of the cabinet bottom to get all of the screws out. Remove the doors of the cabinet. If your Bigfoot has a stereo then remove that too, as well as your speakers. There was also wiring going through mine for a light fixture. Be sure to disconnect your battery and shore power before you cut or disconnect any wires. Label the connections so you can butt them back together later. The cabinet is screwed to the ceiling, the walls (front and both sides) and the cabinet it's butted up against. If it won't come down there are more screws holding it on somewhere. Don't yank on it, it's barely holding itself together and you can easily break it. Look for more screws or bolts holding it on. Then it can all come down. Stash it outside of the trailer.

Now everything is ready to start tackling those rotten walls:

Next step is the corner bracing. They have a piece of 1/8" plywood over top the 3/4" plywood brace, so gently pry off the 1/8" trim and save it for reinstall if it's not rotten. If it's rotten save it for templating your replacement piece. Then the corner braces themselves, they're "stitched" onto the 1/8" plywood skin with several staples, do your best to pry these off without damaging them or the walls that they're butted to. If it's all rotten then pry them off and save them for templating your replacement parts.

Next comes the wall skin. I used a 3" flex putty knife and a hammer start to pry/chisel the 1/8" plywood off of the styrene foam. If the plywood is rotten like mine then this is messy. There may be mold in here, so wear a respirator or at the very least a dust mask. Keep at it, this can take a while.

Next it's time to assess wet styrene foam. I chose to remove anything that was wet as I didn't think I could dry it out in a reasonable amount of time. BE CAREFUL. The fiberglass underneath is only 1/8" thick chopped strand. This can delaminate if you're too rough when you remove the foam and adhesive. I used the same 3" flex putty knife and hammer to pry/scrape off the 1" styrene foam. Be sure to cut square joints so you can have an easy to cut shape for installation of new foam.

There's also structural 1" plywood throughout the walls of the trailer. It's either for mounting exterior fittings (like the awning rail, front window rock guard, windows, exterior hatches etc) interior fittings (table, cabinets etc') or a substrate for the screws that hold the seam of the trailer together. If this is soft or even the least bit rotten looking then replace it while the walls are open. It's a critical part of the structure of your Bigfoot and it needs to be in solid shape. You can use solid wood, buy 1" plywood, or go the route that I did and laminate a piece of 1/2" and a piece of 5/8" plywood together to get a true 1" piece of plywood. The windows are the trickiest bit, I used a combo of solid wood and plywood for those frames, and I primed them with (white) paint before installation too. I glued my plywood back onto the fibreglass with sikaflex 291, but some PL premium will do the job well too.

Now let everything dry out. I put a couple of fans in my unit and heater and left it for a few days. Once everything is dry it's time to start installing the foam board. You can buy the 1" polystyrene foam from home Depot or Lowe's, it's not cheap but you'll definitely need it. There are two options for gluing the foam to your fiberglass and your wallskin to your foam. You can buy PL300 foam board caulking, or you can use a water based contact cement. I opted for the contact cement to get a fast bond, which was critical for attaching the wall skin. I also used a high density 1" fibreglass insulation (yellow) for the corners of the trailer where I couldn't get the foam board to fit in nicely. It was superior to the original insulation by far.

For the wallskin I used two different materials, but I would recommend veneered 1/8" plywood for its appearance and cost effectiveness. If you're going to try to match your existing interior then make sure your veneer is red oak. You can stain it to try to match the dark fake oak paper laminate, but I just oiled mine and then treated it with a rubbed on polyurethane. After I cut it to fit, oiled it, and put a finish on it then I glued the plywood to the foam board. The only disadvantage to using contact cement is that you need to ensure you place your plywood in exactly the right spot, that instant bond isn't forgiving when it comes to relocate a piece thats already been bonded. If you're not confident in your hand skills, PL300 is a better option for you, but you'll need to find some sort of way to shore up the plywood to ensure a good bond.

After all that is done, reassemble as you disassembled. I took the open walls as an opportunity to run new wiring for a vent fan, you may choose to do so while everything is open. I also made some new pieces of trim to clean everything up a bit.

My awning rail was also leaking, remove the screws from the awning rail one by one (you'll need to partially unfurl your awning to access them) fill the holes with a good RTV sealant and reset the screws back into the trailer. This is a cheap and easy fix, it would have been best to remove the entire awning rail and re-set it back on with butyl tape but I didn't want to remove my awning entirely, so this worked.

Now install those windows, remove the butyl tape and poly patch and clean off the fibreglass as well as the aluminum wild a mild solvent like isopropyl alcohol, apply butyl tape and seat the windows back in. Then install the interior frames and tighten the screws (NOT TOO HARD).

Bing bang boom, now your trailer is fixed and ready to hit the road!
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Old 04-10-2019, 04:10 AM   #2
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Name: Mike
Trailer: 1986 Bigfoot FT20
Posts: 856
Nice job Tim! Don’t beat yourself over your zeal to get into your Bigfoot. Great choice!
Be grateful you have the skills to do the repairs yourself.
You now have a great camper you can use for years to come. And the knowledge you can repair anything that comes at you.

Delamination is a problem with bigfoots, And is easily overlooked. The major problem is the contact cement used. Which is water based and when it becomes wet, guess what? It releases.

Other areas overlooked on bigfoots, are the running lights. They also leak, and need to be removed, cleaned of old putty and re-installed. Water egress around lights wicks down and delaminates the Fiberglas and foam. Now you not only have a water issue but, a structural issue.

While your at it, the bathroom vent should also be removed and cleaned and re- installed. Lap seal works to insure it’s sealed. This vent tends to leak with time. It’s hard to catch, because the water will hit the fg ceiling and travel down the bathroom wall. And you find yourself asking, where did that water come from in the middle of the floor.

Some preventive maintenance on key areas, will keep camper tight and dry. The other windows may need attention also.

Great job and nice write up. One of the best I’ve seen regarding delam issues.

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Old 04-10-2019, 07:46 AM   #3
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Name: Fred
Trailer: 13 ft Boler
Kootenay's of BC
Posts: 858
Tim, probably the reason you may have missed some of the trailer's problems.
We (fiber fans) feel pressured to buy because just finding one is a challenge.
Rose coloured glasses are a problem for me too.
But your confidence in your ability to fix things allows you make those mistakes and still come out the winner!!
Great job!!
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Old 04-10-2019, 10:25 AM   #4
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Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 27
You're right regarding the running lights. Mine were growing moss inside the coloured lenses and needed to be removed, cleaned out and resealed to the fibreglass. I'm fairly certain that they were a major source of the damage to my walls.

I also needed to remove my front rock guard and struts and reseal all of those seatings.

I also removed all of my exterior hatches and panels and resealed those.

The only things I haven't touched (at this point) are the roof vents, as they are already lapsealed. However I have been thinking of removing them and resealing them as I don't trust their integrity. The bathroom one is definitely potential hidden leak source! Maybe that will be a project for this summer after I finish my tongue modification.

It never ends.

Thanks for the comments and appreciation! I didn't see any info on wall repairs on this site so I was hoping to make a sticky for DIY Wall repairs.
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Old 04-10-2019, 10:43 AM   #5
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Name: Justus
Trailer: Hymer Touring GT
Posts: 247
I keep telling myself that when we're finally able to get first dibs on a trailer, we won't be wearing rose colored glasses. That we'll do a thorough inspection and walk away at signs of trouble.

We'll see. But posts like yours certainly help me stay realistic about the time and effort involved in repairs! I found out I had a problem when I started on some remodeling projects in our first home. "I can probably have this finished by next weekend" was an inadvertent lie my wife heard many times.
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Old 04-10-2019, 08:50 PM   #6
Name: JJ
Trailer: 2008 Bigfoot 25RQ
Posts: 70
Very, very nice job, Tim!

My previous 25RQ went through a drenching rain for several days and I noticed that there was inside leakage around the window frames inside that penetrated the a wall.

I spent the better part of a week drying out and repairing.
I spent several more days removing all the windows and putting new butyl tape, adding insulation, then re-setting them.
When it rains, the rain comes off the radial roof and down onto the windows and frames. There is no channel or diversion. So, I bought some EZE RV Gutter material from CW. Comes in a roll and I cut the pieces for the width of each window plus the radius on each side to divert water and stuck them, on as they are self adhesive.

Let me tell you, THIS WORKED WELL! Water was now channeled and diverted away as opposed to running down the frame and window.

I did the same to my newer unit as well.

But I'm sorry you learned yours the hard way! The good news is, it is fixed better than ever. That's the thing about DIY'ers and RV repair. We tend to make sure the work is properly done, and usually done better than factory repair.

One last thing: on my current unit, a 2008, I was prepping for summer camping last year in my driveway. I started by filling the holding tanks to sanitize.

Then the THUMP and water coming down the driveway. I couln'd see anything out of the ordinary. My initial thought was that the fill tube on the fresh water tank had separated as the leak was coming from that general area underneath. I took off the coroplast from the underside - no leak. The water was traveling from 1 sheet of coroplast in the rear to the next, and the last where the fresh water tank was. Bottom line, the black tank dropped when I filled it to clean it. It literally dropped out of it's channel.

I could not get the tank to stay in place and was very disappointed at the engineering design rv manufacturers used to hold the tanks in place. This happens more than one thinks, and I don't drive with full tanks, at least very far until I hit the dump station.

I had a welder build some steel straps across the bottom to ensure that the tanks would be held in place. I left some room for expansion, but I sure as heck didn't want the tank falling out while I was driving down a road somewhere.

You might examine yours and make sure they are fully channeled. As the tanks fill, they can pull away from the channels on each side leaving a very, very small ledge for the tank to cling to. There is a adjustable L brackett attached to the frame that has some minor allowance to get a secure fit, but it may be to little of one to be effective if the tank sags in the middle from weight.

Anyway, enjoy now! Lots of places to go!
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Old 04-24-2019, 02:13 PM   #7
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Name: Kate
Trailer: Bigfoot
Posts: 1
Tim--Thanks for posting this and the instructions on repairing floors. We faced a very similar situation with our newly purchased 2006 Bigfoot 25RQ. Your pictures and instructions gave us the confidence to dive in and do the repairs. Once we are done, I'll try to post some pics illustrating what we are learning. Most important, so far it isn't as difficult as it looks. Can't thank you enough for your positive attitude and encouragement!
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Old 05-02-2019, 10:41 PM   #8
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Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 27
Originally Posted by Katekin View Post
Tim--Thanks for posting this and the instructions on repairing floors. We faced a very similar situation with our newly purchased 2006 Bigfoot 25RQ. Your pictures and instructions gave us the confidence to dive in and do the repairs. Once we are done, I'll try to post some pics illustrating what we are learning. Most important, so far it isn't as difficult as it looks. Can't thank you enough for your positive attitude and encouragement!
You're welcome Kate, my intention was exactly that, to help people who are in a similar situation to me when I bought my Bigfoot. I'm very glad that I've given you the confidence and a little know-how on how to do the job. I'd love to see your photos of the repairs, keep me posted.

Best of luck, and most importantly: have fun.


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Old 02-05-2020, 09:48 PM   #9
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Name: Josh & Sonya
Trailer: '97 Casita SD 17; 03 Bigfoot 25RQ
Posts: 126
Hi Tim,

Could you post a link to your Bigfoot floor repair work?
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Old 03-14-2020, 04:41 PM   #10
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Name: Joanna
Trailer: Northern Lite
British Columbia
Posts: 14
me too... :(

Hi Tim,
Just found your post on rebuilding your bigfoot walls. I have found myself in a similar scenario - bought a trailer in a hurry last spring. Prev owner said they had condensation issues (noticed some peeling paint around the windows). Turns out they straight up leak and all the wall panelling on the front, back and driver side are rotten in various places. All the wall pieces are joined behind the furniture, so I'm having to rip everything out.
Anyway, as I remove 10,000 awkward screws I'm thinking about how to put it back together to look a bit nicer. I have a Northern Lite, which was only made for a few years in the 90's, and it has foamboard covering the fiberglass on most walls, covered by white painted lauan (or some sort of thin panel). The foam board does not go to the corners, it had the soft pink batt type insulation behind the lauan there. The corners were pretty wide as well, so my main question is, how did you get such nice tight corners on your bigfoot? did you build those little panels, or buy them somewhere?
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Old 03-14-2020, 09:09 PM   #11
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Name: bill
Trailer: 2013 Escape 19; 1977 Trillium 1300
The Mountains of North Carolina
Posts: 2,651
You are being very helpful with your open and honest appraisal, review of mistakes made, and success in overcoming the challenge. In this age of the internet, stories like yours should be read by shoppers before they buy. Lots of misunderstandings about molded FG trailers such as "they have no wood in them because they are fiberglass". On the vintage ones, every brand has its pluses and minuses. None are perfect.
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Old 03-24-2020, 08:08 AM   #12
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Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 27
Hi Josh and Sonya!

Here you go:

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Old 03-24-2020, 08:48 AM   #13
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Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 27
Hi Joannad!

My insulation is a mixed bag. I have the original stuff (pink) the new hard foam (blue) and my soft fiberglass batts for the corners (yellow) I did all the hard foam first, then I had some 1" fiberglass batting that I cut to fit the corners afterwards. I just measured carefully and cut to a tight fit. I definitely notice a difference between my repaired sections and my original when it's snowing! My original corners leak heat like a sieve, my new ones are as tight as the hard foam.

Unless by the corners you're talking about my wall panel coverings? There are 3/4" plywood plywood corner braces that join the wall panels at the corners, these are "stitched on" using crown staples, and then there are pieces of the wall-skin with some beading around the outside that are pinned on top of these corner braces to cover them.

Hope that helps!
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Old 03-24-2020, 08:49 AM   #14
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Trailer: Bigfoot 17'
British Columbia
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Thanks Thrifty Bill!

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