What causes soft floors

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

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.

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.

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.

For the record.. I HAVE repaired the subfloor on my 1984 TT which was damaged from water leaks that the previous owner didn't fix. The subfloor on my 1984 IS 1/2" plywood.

Yes, it IS GLUED to the foamcore below it, but I was able to remove the damaged plywood between the wood studs. Wasn't pretty but it most certainly is fixable. To add replacement plywood I had to add some supports for the ends of the plywood, easy enough, just dig or cut out some of the foam and lay in the wood reinforcements.

The big problem is not the "sandwich" but the fact that many manufacturers are not using 1/2" plywood as the subfloor, instead they have thinned that down to 1/4" or less.

Gdetrailer wrote:

Lantley wrote:
Does it matter which part of the sandwich is faulty. If it's the thickness of the plywood portion or the density of the foam either way the product loses its rigidity and creates soft spots.
Why the sandwich fails is less important than the simple fact RV manufactures are continuing to use questionable products and questionable construction methods. The consumer ends up holding the bag of soft floors!
I agree sandwich construction is generally found in "Lite" units.But I don't believe it's exclusive to light units.
The real bottom line is units that don't use sandwich construction are generally more costly which makes those units less desirable to $$$ focused consumers.

Your avoiding my question :h

Please point out the exact models and manufacturer brands which does not use a "sandwich" floor construction.

If you can't point out any models, then say so and then stop referring to that method as sandwich..

Sandwich is not the proper term for the construction of composite floor, wall or roof.

I 'm not concerned that its the proper term. This is not a grammer or construction forum. I'm using the term sandwich because its the proper description. Everyone reading this including you understand what I'm saying in terms of how the floor is constructed.
By the way I'm sure I'm not the first or last to describe the floor as a sandwich.
For the record Artic Fox states in their brochure that they use T&G plywood as their sub floor decking.
Sandwich construction is pouplar but it is not the only method being used for floor decks. But again many are not aware of the eventual soft floor issue.
Many are not familiar with other construction techniques and materials.
They simply are not aware: of the need to upgrade to something better, or gamble with the consequences of sandwich construction.

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.

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.

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.

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.

Lantley wrote:
Does it matter which part of the sandwich is faulty. If it's the thickness of the plywood portion or the density of the foam either way the product loses its rigidity and creates soft spots.
Why the sandwich fails is less important than the simple fact RV manufactures are continuing to use questionable products and questionable construction methods. The consumer ends up holding the bag of soft floors!
I agree sandwich construction is generally found in "Lite" units.But I don't believe it's exclusive to light units.
The real bottom line is units that don't use sandwich construction are generally more costly which makes those units less desirable to $$$ focused consumers.

Your avoiding my question :h

Please point out the exact models and manufacturer brands which does not use a "sandwich" floor construction.

If you can't point out any models, then say so and then stop referring to that method as sandwich..

Sandwich is not the proper term for the construction of composite floor, wall or roof.