Spongy Floating Floor on 24' Thor Synergy RV

GeorgeL

New member
I own a Thor 2017 Synergy SP24 with Sprinter chassis. It's floating floor has developed at least three soft spots, one at top of stairs, one by the bathroom and one by rear bed. In the first year, the softness appeared and a Lazydays dealer attempted to resolve it by injecting a glue type substance. The softness came back and has increased.

Has anyone had this problem and how have you resolved it? Options I have learned of include, putting a new floor on top of it, take off existing floor and replace, further injections, or just live with the softness.

One person suggested that the exhaust system puts out high heat in certain areas and this damages the foam layer. Also, a high degree of use accelerates the problem. Who would ever imagine that you would buy a house that has a poorly designed and manufactured floor.
 

Mike DZ

2016 View 24V (2015 3500)
I sympathize with your plight and agree that RV floor laminate is a poor design for the consumer. It is a money and weight saver for the manufacturer. However, not all consumers get the soft spot problem. I don't know why.

I installed click-lock floor from Lowe's over the existing, except in the bathroom. It was a very fiddly job. Lots of small cutouts and not many straight lines. Also it added weight to my rig. On the plus side it reduced noise. I removed some underfloor noise baffles I had previously installed to take care of a different problem, to minimize the weight gain.

I still can feel a little flex in one spot. I would probably do it again if I had a similar problem, but would have a better understanding of how time consuming the job would be.
 

Yosarian

New member
Just beginning renovates on a 2011 24SB Chateau Citation Class C. Floor is soft in spots (the top of stairs, in front of frig & at rear bath door). A leaky skylight left ceiling substarte rot, so the headliner has to come out to fix it proper. That being the case, I figure to take up the floor as well since the top cabinets and floor to ceiling cabinets have to come out anyway. By the time I get into it I may well end up gutting the entire thing since I can't stand doing things half arsed.

In conversation w/ a Thor Master Tech he confirmed that the floor sits on their sub-frame and that the walls are lagged through their bottom plates and into the edge of the sub-floor deck. That means that a 100% deck replacement is impossible unless you literally detach the lags and lift the entire remaining coach structure from the deck, and that just ain't happenin', so there are limits to how far I can practically go.

I suppose the biggest issue is that you need to determine if the damage is from water intrusion or insulation degradation. If it's the former, then the next question is whether or not the original source of the problem has been adequately addressed. Nothing spells fun like having to do things twice.
 

Mike DZ

2016 View 24V (2015 3500)
In my Winnebago, the floor is a sandwich of thin aluminum, foam and then luan (very, very thin plywood) and finally vinyl. The foam is a major structural element, no just insulation. Unlike olden RVs, there is little chance of softness due to water intrusion. Most of the time it is foam compression, which the luan can't sufficiently bridge. I can see the cross section in the back where the floor is cut at the factory for water lines.
 

Yosarian

New member
Yeah, luan seems to be a favorite component with these jokers. It appears to be what my headliner is glued to, and although it has been used under floors for decades, it has never been adequate for any of the flooring manufacturers to warranty their product when luan (aka - lauan) is used under it. So I guess it makes sense that an industry dedicated to preventing regulation or any kind of real standards would love it, but I digress.

Straight luan is rather generic, but basically, it's all crap, and the glues used to hold it all together are definitely not capable of dealing with moisture. So whether they've used it by itself as a substrate, or employed it as part of some kind of Frankenstein composite panel, it's still junk. There are of course better alternatives, but I suppose the manufacturers have decided that whatever looks good and helps them push as much crap as possible, as fast as possible, out into the marketplace is what's most important. I suppose it makes sense, since the age of more and more people losing their homes and ending up in RV's as an alternative has been a big part of this last decade plus (and it's accelerating more and more every day) so this has all been a goldmine for the RV pirates, and it appears it will continue to be.

This all reminds me of the big three US auto makers back in the 70's, when they went before Congress and all whined about how hard it was to do anything at all to build cars that polluted less and how many decades they claimed it was going to take them to even begin to think in those terms. Then, and I believe it was the very next day, the founder of Honda sat down and told the Congressional committee holding the hearing that not only did his CVCC engine already meet the more stringent emissions requirements being considered, but Honda was already a decade ahead of where they hoped to eventually take the regulations. The issue of quality and improved engineering is all about corporate will and profit. The Japanese took the attitude that building the best of something will eventually win market share, whereas most US manufacturers have traditionally focused simply on this quarter's profits and how to make more bigger cheaper faster, and it shows - sadly. Of course there are exceptions, but they continue to be more and more rare.

As it applies to the RV industry (and the U.S. based portion of that in particular) there are so many new and amazingly efficient materials and types of equipment out there, that could be employed to build some truly wonderful units, that it's absolutely staggering. The Euro-styled windows come immediately to mind, but here the manufacturers are still acting like their foggy old double pane junk is somehow special because they now have a frameless one that looks cool? The leading cause of fires in RV's has been, for a long while, LP fired refrigerators. There are incredibly efficient and better performing all electric DC components available (and there would be exponentially more if they were made the industry standard) but the big builders are still selling the old tech as if it were something to crow about. I think worst of all however is the issue of just how these box builders construct their bolt-on boxes.

There are ceramic matrix composites available that can be run in a continuous production type configuration (vs. the old and expensive batch type) somewhat similar to way these cheaper foam composites are formed. The result can provide incredible strength to weight, I think it was something like R-30 in about a 2" cross section, and depending upon the orientation of the Z-axis fibers (these are reinforced in three dimensions) can actually stop bullets? Pretty amazing stuff, and of course, the more companies that use it, the cheaper it can be made and distributed, but no, they're still building with sticks and stuffing fiberglass (one of the world's worst insulators) between the sticks. That all supports mold, and none of it can deal with moisture, but still they persist. It always makes me laugh when I hear any of their sales pukes attempt to elaborate on any makers' insulation "package". They're all oversold thermal catastrophes that function more like a thermal seive.

Sorry to rant, but it's cathartic.

Build a tighter box with higher long wave radiation reflectivity and more resistance to thermal transmission (higher 'R'), put truly efficient windows and doors in it, and presto - suddenly your heating and air conditioning loads are cut in half, or more! So instead of sweltering in your leaking box while the generator drones on emptying your diesel or LP tank by the minute, we could be enjoying truly comfortable conditioned air spaces using half or less the energy, which in turn makes smaller and less expensive solar solutions all that much more viable. It's not really that complicated, but they would have you believe so. The same happens with solar - it simply doesn't have to be so complicated.

Instead of trying to fit a 10 kw array on a roof, why not build a more efficient box that doesn't need all of that? We should already have 48 volt solar roofs with integrated Tesla Power-walls available, powering high efficiency A/C, silent hydronic heat, hugely efficient refrigeration, and fume-less induction cooking, as well as direct solar water heating w/ PV boost for endless hot water. Taking a 10 or 20 year loan might actually start to make a little sense then (although I would still argue the contrary, but that's for another rant). NO, instead we have one of the biggest RV manufacturers in the world building crap that can't even provide a solid floor after just weeks or months of use? Yeah - pretty freakin' pathetic, but I'm sure profits are up.
 

Kajtek1

2015 long/tall limo RV 2.1l
Several members used vinyl planks for the floor with excelent results, so if you want to replace your wood, or whatever planks, that is what I would do.
The only note about vinyl - it is not having much mechanical strength on joints.
My bus had holes in factory floor for seats, that I plug with piece of wood. I had like 1mm height difference and vinyl plank joint come right over it, so when I step on it, it split. Still easy to take damaged plank and replace with another one.
 

Aqua Puttana

Poly - Thread Finder
Just some opinions.
FWIW. I agree that RV floor designs are not the best.

Most every time I have found soft floors in RV's it has been related to water damage of some sort. The water gets in and never dries out.

If the problem is foam or other filler compression then installing snap together flooring over the existing should stiffen things up. Snap together flooring is fairly heavy though. With a Sprinter RV that could be a factor to consider. I suppose that's true for any RV though.

There are strong injectable foam products which are designed for applications like under fiberglass shower pans. A problem is that the existing foam or other filler will prevent the new foam from spreading to where it is needed. A boat repair trick. Often a bent nail is used to chew out the core to open a cavity. That allows a "puck" of resin to be formed for support. I sometimes mix in a bit of chopped strand for strength.

The easiest, but still a bit involved might be to plan on replacing the flooring with decent quality loose laid vinyl as has been mentioned. That allows the soft sections to be opened up for repairs. The new vinyl will cover all of the repairs.

After some floor repairs we replaced the vinyl floor covering on our Jayco trailer. We used a remnant from a local flooring store. I basically stapled the perimeter down. It turned out well. There were a couple places where my cutting/fit wasn't so great. Some small section quarter round trim dressed that up.

:2cents: vic
 
Own a 2017 24SS Thor Siesta Sprinter whose floor boards went spongy after a year. Lived with it then took it to dealer (Camping World) who wanted 6000 to pull out installations inside, replace floor, etc. I said Not until I get another bid. Took it to Columbia MO RV repair. Problem turns out not to be bad filler but bad engineering. Thor does not brace the floor properly. After my man added new braces under the chases the floor is now stiff as new shoe leather. Cost 1100 dollars.
 

OkieNAz

Randy
I purchased a THOR 24SA in early 2014. We spent over 400 nights in the RV in a little over 3 years. The floor started getting soft right next to the entry steps after about a year. The softness began to spread out every place we walked. It was still very solid under everything that was secured to the floor. As I was trying to figure out what was going on, I found that the THOR Sprinter based RV's have a floor made of Styrofoam sandwiched between two then layers of maybe a PVC film (some sort of plastic) with linoleum covering. I took two core samples of the floor in out of the way places expecting to see some type of reinforcement or maybe even some water damage. Nope, just a Styrofoam floor. No water damage at all. I am sure that THOR took this approach to save weight.

I took the RV to J&L RV Repair, Fontana, Calif. and had them reinforce the floor. J&L glued 1/2" weather proof plywood to the underside of the floor and then braced each piece of plywood with angle iron fastened to the cross pieces under the cabin. I lost some of the storage through the pass through located under the floor. The only place that could not be reinforced was in the bathroom. Too much plumbing/tanks under that area to place a plywood support.

I weighed the RV after fully loading it for a long trip after the reinforcement was installed. The 24SA still weighed in at less than the weight limits.

I would say that the floor was about 95% back to the same stiffness it was when we purchased the RV.

J&L gave me an estimate over the phone. The actual work took a few hours longer than they had estimated but I would give J&L RV Repair an A+ for customer service and for actually performing the work that had been promised. It took about a day and a half for them to complete the job on my RV.
 

GeorgeL

New member
I purchased a THOR 24SA in early 2014. We spent over 400 nights in the RV in a little over 3 years. The floor started getting soft right next to the entry steps after about a year. The softness began to spread out every place we walked. It was still very solid under everything that was secured to the floor. As I was trying to figure out what was going on, I found that the THOR Sprinter based RV's have a floor made of Styrofoam sandwiched between two then layers of maybe a PVC film (some sort of plastic) with linoleum covering. I took two core samples of the floor in out of the way places expecting to see some type of reinforcement or maybe even some water damage. Nope, just a Styrofoam floor. No water damage at all. I am sure that THOR took this approach to save weight.

I took the RV to J&L RV Repair, Fontana, Calif. and had them reinforce the floor. J&L glued 1/2" weather proof plywood to the underside of the floor and then braced each piece of plywood with angle iron fastened to the cross pieces under the cabin. I lost some of the storage through the pass through located under the floor. The only place that could not be reinforced was in the bathroom. Too much plumbing/tanks under that area to place a plywood support.

I weighed the RV after fully loading it for a long trip after the reinforcement was installed. The 24SA still weighed in at less than the weight limits.

I would say that the floor was about 95% back to the same stiffness it was when we purchased the RV.

J&L gave me an estimate over the phone. The actual work took a few hours longer than they had estimated but I would give J&L RV Repair an A+ for customer service and for actually performing the work that had been promised. It took about a day and a half for them to complete the job on my RV.
It would be helpful to know approximately what it cost you to have the work done by J&L. Also, did they remove the old vinyl flooring, then reinforce the floor, and then install new vinyl flooring? Also, I am assuming they did not remove the cabinets such as under the kitchen sink and reinforce those areas.
 

GeorgeL

New member
Own a 2017 24SS Thor Siesta Sprinter whose floor boards went spongy after a year. Lived with it then took it to dealer (Camping World) who wanted 6000 to pull out installations inside, replace floor, etc. I said Not until I get another bid. Took it to Columbia MO RV repair. Problem turns out not to be bad filler but bad engineering. Thor does not brace the floor properly. After my man added new braces under the chases the floor is now stiff as new shoe leather. Cost 1100 dollars.
Thanks so much, Robert, for that information. What is the process for adding new braces under the chases? How do you get to the chases?
I apologize for not knowing this. Who would I speak with at Columbia MO RV repair about this?
 

GeorgeL

New member
It would be helpful to know approximately what it cost you to have the work done by J&L. Also, did they remove the old vinyl flooring, then reinforce the floor, and then install new vinyl flooring? Also, I am assuming they did not remove the cabinets such as under the kitchen sink and reinforce those areas.
By the way, I want to thank you for taking the time to write to me about your spongy floor and how you resolved it. Happy New Years Eve.
 

OkieNAz

Randy
The cost if the repair was a bit over $2K.

I had first taken my RV to a notable repair shop in Mesa Az. After the repair guru looked under my RV, he said I should take it back to Thor for repair.

Thor just wanted to lay another thin support sheet and new vinyl over the top of the actual floor. That did not sound like a very good idea to me. That might have worked, but I chose not to go that direction because I couldn't see how they could build up the floor under the slide (to my satisfaction) and I didn't want to have a "lip" right at the steps as we walked in.

I had bounced ideas off of the late "Old Crow" on how to solve the soft floor problem. We concluded to have the floor reinforced from the under side might be the best fix.

J&L raised the RV on a lift to do all of the work. They cut marine grade plywood to fit against the under side of the floor in each section that was soft (all except under the bathroom). J&L painted the plywood on the bottom side before gluing the pieces in place. Then angle iron strips were bolted to the RV framing so that the plywood would be well supported. (Darn, I can't find my photo's of the repair job.)

So nothing was moved on the inside of the RV. I was pretty happy with the results from J&L.

Good luck, Happy New Year and safe travels in 2021.

By the way, I implemented most of the modifications that were recommended by the Old Crow on this forum.
 

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