What causes soft floors

[mkenyon2]

What causes soft spots in floors? What can be done to prevent that? How serious is it?

I'm guessing soft spots are areas where the subfloor (plywood or OBS) has gotten moisture and weakened. I'm wondering if it happens more when parked on a grassy lot vs a paved area?

I also understand that how serious it is is subjective to the area that's gotten soft and the model of trailer.

My question comes up as I look for a used travel trailer and have seen some nice ones with soft spots.

[mdcamping]

^ yes you are correct, guess I was thinking more about my 2011 Jayco & prior thor aerolite.

I still have faith in some of the newer Jayco products

Mike

[Skibane]

^Jayco was purchased by Thor in 2016.

[mdcamping]

^^ yikes, yeah that is very scary. I was lucky with my thor as the damage was located in the front 1/3 of the trailer so no slides or appliances to deal with. I removed my seating and was able to go wall to wall with new plywood.

Theres probably a zillion of these floors out there and I read online about spongy floors all the time. My present Jayco has the similar type floor, floor is solid though. (Jayco seems to do a better job on construction vs thor or others) 🙂

Mike

[MFL]

Skibane wrote:
Pertinent YouTube video:

https://www.youtube.com/watch?v=yE0fh-cGSec

^^Very interesting video! Not going to be a fun watch, if you are the owner of similar trailer. Almost all later model trailers have a slide out, like one in video. This makes adding flooring, making it thicker a real challenge.

I can see why someone with an old trailer, no slides, could cobble the flooring by adding thicker plywood, and just meeting cabinets, repairing just the walking traffic area.

Jerry

[Skibane]

Pertinent YouTube video:

https://www.youtube.com/watch?v=yE0fh-cGSec

[mdcamping]

"What causes soft floors"

In my case of my past thor, it was wicking up from underneath most likely caused from condensation. Tailer had no delamation, no roof leaks, nothing anywhere I could find a leak source. Floor construction: starting from down going up was very thin sheet metal,lauan,styrofoam, lauan then topped with linoleum all glued.

I ended up dremming out patches of the sheet metal, replaced with bug screen. This allowed the wood to dry out underneath and on the top side I cut out the linoleum, allowed the wood to dry out and topped with new plywood and those stick on linoleum tiles. This was not a cure all but certainly a heck of a good remission repair. I ended up getting 11 years out of a poorly constructed trailer.

Mike

[Lantley]

Huntindog wrote:
FWIW I have had a 1975 Prowler, 2001 Fleetwood Wilderness. 2010 Palomino Sabre, and now a 2021 GrandDesign Momentum.

None of them had the types of floors that you all are speaking of (BTW, I call them Sandwich) I would not ever buy one of those. I have friends that had problems, as well as reading about it online.
It is possible to buy one without it... Yes it may cost a little more, but how much will that problem child cost down the road?

Huntingdog maybe you'll be more convincing than me. Nothing I said made any sense including the term sandwich

Problem down the road you say!
It won't be a problem at all. Just put down some 1/4" luan and everything will be fine.:R

[Huntindog]

FWIW I have had a 1975 Prowler, 2001 Fleetwood Wilderness. 2010 Palomino Sabre, and now a 2021 GrandDesign Momentum.

None of them had the types of floors that you all are speaking of (BTW, I call them Sandwich) I would not ever buy one of those. I have friends that had problems, as well as reading about it online.
It is possible to buy one without it... Yes it may cost a little more, but how much will that problem child cost down the road?

[Gdetrailer]

Lantley,

[Gdetrailer]

Lantley wrote:

Gdetrailer wrote:
Oh, yeah, by the way, you CAN fix those softspots that they will never come back again.

Once you have cut out and replaced the soft subfloor, you now lay a layer of 1/4" luan over top of the floor and put down new vinyl or new carpet. You simply glue and nail down the luan and that added layer reinforces your floor. Yes, it adds 1/4" to the floor height but it should be no issue. You do not have to laydown the extra layer under cabinets or any other immovable object. Only needs to be done where you walk.

These things can be fixed much easier than you think.. That is a weekend project and if you are slow at it perhaps a 2 weekend project.

The soft floor is generally a structural problem. 1/4 plywood is not known to be very sturdy or structural. It generally used to create a smooth surface but it's not used to provide substantial structural integrity. The only thing 1/4" plywood may due is mask the problem and buy some time until the softness returns.
If you decide to overlay with 1/4" it needs to be done not only in the areas you walk but it needs to be done wall to wall. If the new plywood ends at a cabinet is there ample support at that seam?
cross your fingers and hope...LOL.
By the way are you screwing this 1/4 plywood into joist or are you just screwing it into the existing compromised panels?
In closing soft floors are unfortunately a all to familiar isue especially in lighter weight RV's.
The fix is not easy. The real solution is to build the RV's using a better technique in the first place.
There are fixes that can be done after the fact. But they are generally not simple,foolproof or universal. Each case is different and will require a different approach depending on severity

No matter how wrong you are, you keep insisting on being wrong. :h

Complaining just to complain?

Obviously you have never tried and have no interest in learning how to correct the problem.

There is zero reasons that you would need to put an additional layer luan under cabinets and built in furniture.. It isn't like you are walking under the cabinets or furniture.. The structural support under the WALKING areas is what is compromised.

Only need to lay the luan over the WALKING areas. Yes, it IS this simple to fix. Quit making it difficult.

As far as screwing/nailing/stapling the luan goes, it is easiy to figure out where the studs are in the floor, find them and screw, nail, staple the luan in those places.. By the way, they do make "stud finders" which work very well on finding those floor studs..

[Lantley]

Gdetrailer wrote:
Oh, yeah, by the way, you CAN fix those softspots that they will never come back again.

Once you have cut out and replaced the soft subfloor, you now lay a layer of 1/4" luan over top of the floor and put down new vinyl or new carpet. You simply glue and nail down the luan and that added layer reinforces your floor. Yes, it adds 1/4" to the floor height but it should be no issue. You do not have to laydown the extra layer under cabinets or any other immovable object. Only needs to be done where you walk.

These things can be fixed much easier than you think.. That is a weekend project and if you are slow at it perhaps a 2 weekend project.

The soft floor is generally a structural problem. 1/4 plywood is not known to be very sturdy or structural. It generally used to create a smooth surface but it's not used to provide substantial structural integrity. The only thing 1/4" plywood may due is mask the problem and buy some time until the softness returns.
If you decide to overlay with 1/4" it needs to be done not only in the areas you walk but it needs to be done wall to wall. If the new plywood ends at a cabinet is there ample support at that seam?
cross your fingers and hope...LOL.
By the way are you screwing this 1/4 plywood into joist or are you just screwing it into the existing compromised panels?
In closing soft floors are unfortunately a all to familiar isue especially in lighter weight RV's.
The fix is not easy. The real solution is to build the RV's using a better technique in the first place.
There are fixes that can be done after the fact. But they are generally not simple,foolproof or universal. Each case is different and will require a different approach depending on severity

[Lantley]

Gdetrailer wrote:

Lantley wrote:

Gdetrailer wrote:
For the record.. The SUBFLOOR thickness and type of material IS the problem, not the construction method.

Yes, some manufacturers skimp on the subfloor thickness and type of material on some models and that IS the problem.

It's not simply a subfloor problem. Simply replacing plywood is doable.
However it's replacing the sandwich...multiple layers that complicate the repair.

Nope, wrong you are.

Here is a illustration of the "sandwich floor".


Click For Full-Size Image.

That is taken from my 1984 brochure.

Please kindly note the critical area that the red arrow is pointing to.

That is the subfloor and that IS where the problem begins at.

I'm glad you feel the red arrow points to the critical area. But you need a few more arrows. Often the problem is the joist are over spanned. The trailers are built on 24" centers which exceeds the structral integrity of the panels. Another issue is that the foam get weak and flexes been the 2 layers of plywood. Much in the way all plywood is not created equal, All foam is not created equal. Once that flexing begins the soft spot spreads. You end of with weak areas between the joist.
Is it the plywood that fails or is it the foam. I imagine both have issues because soft floors is a very comon issue.
But the biggest is is the repair is not easy.
Its not a matter of simply replacing the plywood because often the foam is compromised as well. Now you get into replacing the entire sandwich while trying to maintain the original thickness.
The sandwhich panel is beneath all the interior wall and furniture.
The panels are most likely under the exterior walls as well.
The other issue is trying to properly support the sandwhich with additional joist. The 2x2 wood framing at the end of the panels are also prone to failure who frames a floor with 2x2 studs?
THe bottom line is the panels fail be it the plywood, the foam or the framing. Leaving unsuspecting owners with soft spots.
This is a known issue that doesn't seem to be getting any better or this thread would not exist.
Interestingly your photo is from a 1984 brochure, you would hope they would have this issue resolved by now. But soft floors are still a common and reccuring topic.

[Gdetrailer]

Oh, yeah, by the way, you CAN fix those softspots that they will never come back again.

Once you have cut out and replaced the soft subfloor, you now lay a layer of 1/4" luan over top of the floor and put down new vinyl or new carpet. You simply glue and nail down the luan and that added layer reinforces your floor. Yes, it adds 1/4" to the floor height but it should be no issue. You do not have to laydown the extra layer under cabinets or any other immovable object. Only needs to be done where you walk.

These things can be fixed much easier than you think.. That is a weekend project and if you are slow at it perhaps a 2 weekend project.

[Gdetrailer]

Lantley wrote:


Soft spots typically don't occur instantly but they develop over time.
By the time a unit has mutiple soft areas the warranties have expired and the manufactures'are off the hook.
Leaving the unsuspecting buyer holding the soft floor bag. That tale repeats itself many times.

Softspots that develop are due to not thick enough subfloor.

Buyers insist on huge lightweight RVs that they can tow with a lawn tractor and they want it CHEAP.

The manufacturers responded to what the BUYERS want, they had to cut weight and quality to fit what consumers want.

You can't have lightweight, quality and cheap all rolled up in one package.

Instead of telling folks to avoid composite floors, tell them to check how thick the subfloor is as that IS where the problem starts.