Bigfoot Floor repair - Fiberglass RV

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Old 04-11-2019, 01:51 PM   #1
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Timwiltshire's Avatar
Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 29
Bigfoot Floor repair

The floor of my Bigfoot 17' needed some TLC. I'd noticed a squishy spot in front of the fridge and the dinette shortly after I'd purchased the trailer. I'd also noticed that my plumbing leaked like a sieve when city water was hooked up to it (I guess the previous owners had also let the lines freeze, not a shocker considering the condition of the trailer when I bought it) and since the squishy floor was under the kitchen cabinet I figured I'd best replace all of the freshwater plumbing while I opened it up to fix the floor.

I'd already learned the anatomy of my trailer from my previous wall repairs, so this was much easier than my initial job on the trailer.

I started by removing the entire front dinette. Unhook the table from the wall and stash it outside the trailer.

Next comes the dinette seats.

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.

I ended up leaving my power box/converter wired up but not fastened down during this whole floor repair. Call me lazy but I didn't want to deal with removing all of those wires when the connections were fine. I had enough slack in the wiring to slide the whole unit around while I worked, and when it got in the way I tied a piece of rope to it as well as the cabinets above it and slung it a few inches in the air. It worked. There was a major burnt patch on the floor underneath the converter, I ended up making a sheet metal spacer with some insulation in it to keep the converter off the floor in the future.

The cabinet behind the driver side dinette seat also had to come out. This one was a real bugger to remove without damaging the rest of the millwork. The top of it has 1/8" doorskin glued and tacked onto it which is fixed to the "shelf" that runs along the front end of the trailer. This had to be removed in order to get access to the screws that were fixing this unit to the wall and the kitchen cabinet run. I ended up using an Olfa knife to cut a joint in the 1/8" plywood skin (on the top of the cabinet) where the cabinet met the front shelf. This allowed me to remove the top of the cabinet without compromising the shelf laminate. From there the 3/4" plywood top of the cabinet could be unscrewed, and then the whole cabinet could be unscrewed from the wall and the cabinet adjoining it. Your hot water tank plumbing runs though this cabinet, you'll need to cut it off in order to remove it the cabinet. As I was replacing all of my pex with this job anyway I didn't mind cutting it and throwing it out. If you do need to cut it and your plumbing is savable then it's not a big deal, $10 in shark bite butt connector fittings will reconnect the pex when you reinstall everything. Make sure before you do this that you've drained your entire water system, including your hot water tank. Stash all the cabinet parts outside of the trailer.

Now the water tank needed to come out. I cut all of the pex lines from it, and I disconnected my propane tanks from the trailer and drained the lines. Now go to the outside of the hot water heater, mine is just propane and not electric, and disconnect the propane fitting from the tank and cover both ends of the fitting with tape to protect them. Next undo all of the screws that are fastening the unit to the wall of the trailer. Using a plastic pry bar, work the flange of the hot water heater loose, gently feed the propane line through the hole in the tank as you remove the entire tank from the trailer. Stash it somewhere dry and safe with the rest of your stuff.

Now it's time for the kitchen cabinets. All the fittings need to come out. The range is a pretty simple job, pop off the top grills and you'll find the propane fitting underneath as well as the 4 screws fastening it to the cabinet. Undo all of these and the range should slide out nicely. Stash it outside of the trailer.

The furnace is a bit more work, take off the face plate and remove the fastening screws. There is also a propane fitting that will need to be removed (and covered with masking tape to protect it) as well as some wires (3 I believe) that will need to be cut. Make sure that you're disconnected from shore power as well as your batteries before you cut any wires. They're colour coded so there's no need for labelling, unless you're just that kind of person. Go to the outside of the trailer and undo the exhaust flange fitting from the outside, slide it out (mine was stuck, it needed a hard pull/pry) and then the furnace should be free to slide out. Stash the whole sucker outside of the trailer.

The fridge is pretty simple. Go to the outside of the trailer and undo your fridge panel (mine snapped into pieces when I undid it, I ordered another one off amazon for $50. It also ended up being the cause of my floor rot as the main flange wasn't caulked or butyl taped onto the trailer, it was just held on with screws) The fridge will have 2-3 connections depending on your unit. There will be a propane one (undo it and tape the connections to protect them) there will be DC wiring (black and white, take some photos of it so you remember where they go) and a regular AC plug in going into an outlet if you have a 3 way fridge. Undo all of these. At this point its a good idea to look at the condition of your fridge drain line, mine was cracked and falling apart. Instead of ordering an OEM replacement part, I went to a hose supply store and bought 3 feet of 1/4" I.D. Beverage hose. It's pretty common and most industrial suppliers should stock it. You'll need to drill a larger hole in the back of your fridge to put this in, but it's worth the piece of mind knowing that your fridge drain line wont cause any future leaks for you. Go to the inside of the trailer and unscrew the fridge mounting screws from the face of the fridge. The whole thing will slide out, you know the drill, stash it outside of the trailer.

The sink and faucet are next. The faucet hose lines just unthread from the bottom of the fixture. There are large threaded mounting screws (just like your home kitchen faucet) on the bottom of the faucet as well, unthread those as well and the whole unit will come out of the counter top. Next undo the sink drain fitting and undo the dogs holding the whole sink down (they're a pain to access, I warned you) Then the sink will need to be pried up from the counter top (mine was held down with butyl) Take the sink and faucet out of the trailer and stash them with your growing pile of trailer parts.

You'll need to cut the hot water lines again, this time closer to the back of the trailer. Then the hole run (it goes behind the fridge) can slide out of the cabinet. Ideally at this point there should just be screws holding the cabinet in place that are all fully visible now. They go into the floor, up the walls, and along underneath the countertop. Undo them all. Mine was still holding on for some reason, I ended up prying it off only to find a screw coming in from the outside of the trailer (under the fridge exhaust panel) as the culprit. This cabinet won't fit out the door, stash it in the corner and out of your way.

Now all of the water lines and the pump are fully accessible. My pump needed to be removed so I could get at the rotten floor underneath it, I left the electrical connections in place but undid the water lines so I could slide the pump slightly out the way while I worked on the floor.

Whew, now you're ready to tackle that floor.

I cut jigsaw blade down so that at the bottom of it's stroke it was 5/8" long. I laid out straight lines on the floor about 3" past the visible rot, and I started to cut. Mine was so rotten it all just peeled up after I cut it. The linoleum fully delaminated from the plywood, but all the screws were so rusty and rotten that trying to drive them out was impossible. The whole kit and kaboodle came out no problem. The foam on the floor was chipped out with a 3" flex putty knife and a hammer. The 1" plywood sleepers basically fell apart, I cut them back with a hand saw until all that was left attached to the floor was good wood.

If your walls behind your cabinet are rotten like mine were then do some tear out there as well. My fridge panel framework was all rotten and needed to be replaced, as well as some wallskin. Contact cement is definitely a must for the wallskin. See my Bigfoot Wall repair post for details on this.

Put some fans on it all and a heater and let it all dry out for a while. Take a break from your trailer project.

Once everything is dry it's time to replace the sleepers on the floor. They line up on top of your frame rails and are what give your floor it's support. They're 1" plywood that's glued down to the fibreglass. Cut them to shape and glue them down with PL premium or sikaflex.

Get a router with a rabbiting bit and run it along the seams of your good floor. The goal here is to remove the top 1/2" x 1/2" of foamboard from underneath your subfloor (but don't cut the subfloor here, just back cut the foam) This way you can slide a scab piece of 1/2" plywood underneath your good sub-floor and screw it in so that your new subfloor will be positively connected to the old. This way you won't have any sagging joints. If you're having a hard time following me then look up a drywall patch set up. Same sort of deal.

Fill in the open spaces between the sleepers with 1" polystyrene foam. I glued mine down with PL300 as there was no need for contact cement here. The subfloor is 1/2" plywood, cut a piece (mine needed to needed to be done in 2 to make it around all the floor fittings) to fit, throw some pl300 down on the foamboard and screw the sucker down. This is where those scab pieces show their value, fasten the subfloor to these. If the new subfloor and the old aren't level then it's time to break out the power plane and work it all until its flat. Be sure to countersink your screws a little deeper than normal so that you don't run over the screw heads with your powerplane.

I ended up leaving a cutout in my subfloor underneath the cutouts for the fridge panel and the hot water tank. There's a gutter of sorts in the fibreglass here that's meant for drainage. I wanted there to be no chance that an exterior leak would rot out my floor again. After I put my flooring in I covered the holes with some perforated aluminum, so that any leaking water would drip through it into the gutter.

I ended up removing my old lino and replacing it with a vinyl tile. I scraped up the lino as best I could, but I discovered (to my delight) the best tool for the job was my small power plane with a vacuum hooked up to it. This made short work of the lino and the vacuum hook up minimized the mess. I removed the lino up to my remaining cabinets and bathroom, using an olfa knife to get a sharp clean joint where the lino was removed up to the base of the existing millwork.

I laid out my lines for tile on the floor and then started to cut them to shape. I ended up installing the tile that went under the kitchen cabinet first, so I could reinstall it and get it out of my way for the rest of the floor. After it was glued and dried I reinstalled the kitchen cabinet and worked on the rest of the floor. After the cabinet was in (but not the appliances) I redid all of the PEX that I could now freely access (including the hot water tank, just make your rough ins and get it ready for final install once the cabinets are back in) and then I reinstalled everything as I removed it. Finally I connected the last of the hot water PEX lines (now impossible to crimp) with two sharkbite fittings.

Boom, there's probably the hardest floor repair you'll do in your trailer.
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Old 04-16-2019, 07:40 AM   #2
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Trailer: 1981 Trillium 5500
Posts: 1,038
nice tutorial, this should go in the document center
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Old 04-16-2019, 01:26 PM   #3
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ZachO's Avatar
Name: Z
Trailer: Sasquatch
Posts: 2,550
I've got the same squishy spot in front of my fridge. I've decided to just live with it...

Nice work! And nice write up.
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Old 04-16-2019, 07:49 PM   #4
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Timwiltshire's Avatar
Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 29
Thanks fellas, it was a lot of work but it was worth it in the end.

How do items get moved into document centers? Do moderators need to do it?
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Old 05-13-2021, 08:49 PM   #5
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Name: Tim
Trailer: Bigfoot 17'
British Columbia
Posts: 29
Bump, as this does not seem to come up when searched.
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Old 05-14-2021, 06:31 AM   #6
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If you want to be able to find it quickly in the future, subscribe to the thread.

For best search results, use the google-based search option at the bottom of the search menu.
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