No floor joists in 2001 trail-lite 30' tt!

Matt... I had a similar problem on my 1999 Bantam Hybrid. Only cross members were at front edge, rear edge, and two others... About 4 feet between them over the 13 feet of floor.
I added a few 6 foot pieces of bed frame about 8 inches apart under the soft floor. I notched each end so that there is 2 inches of flat metal laid on top of the original frame on both sides. Worked great for me going on 3 years now. Will surely have to add more in the future.

mgirardo wrote:
Once the vacuum of the initial install is broken, the floor will be soft or spongy.

I would use the word "seal" or "adhesion", but you are 100% correct.

If you look sideways at that type of flooring and then imagine it is an I-beam. An I-beam is strong because the center vertical piece (webbing) does not allow any movement between the upper and lower sections (called a "flange" on a real I-beam).

Steel/aluminum I-beams are made as one piece, A wooden I-beam (common is houses these days) would fail if the adhesive that that connects the top flange to the web or the web to the bottom flange failed.

The most robust flooring is aluminum decking. Plywood decking will fail if it has standing water on it for sometime (like a roof/window leak during storage).

The issue is the bonded panel for use as a floor. These composite panels are good as a wall structure but will eventually fail if the plywood used in a floor application is not adequate.

FWIW, I have 5/8" CDX plywood in my rig and it is still good after 45 years. I pulled some where the water heater had been drained on top and along one spot under a wall. I replaced it with new 5/8" plywood. The joists are on 16" centers.

Out ATC 28 front bedroom is all metal. Top to bottom. Be careful with liv in lite. Some models are now this foam design. I think the toyhaulers are aluminum. Blame that on Thor.

I'm amazed plywood is used, its pitiful. They could at least use marine grade. Heck Airstream uses plywood. Really worth 80 k

ATC, Sundowner and Becker, still all metal.Buyers beware...

The only problem I had with adding plywood over the existing floor is that I am 6 foot 8 inches tall and even that 5/8 makes a big difference in a travel trailer. My head and the air conditioner have met several times abruptly.

Matts6foot8 wrote:
...1/4" plywood panels sandwiched on 1-1/2 foam. Towards the rear the water,grey,and black tanks support the floor.....

Terrible design, your best bet is to install a plywood floor on top of the existing floor and then whichever floor covering you prefer.

Another possibility would be to install hardwood tongue and groove flooring. T&G laminate flooring will not add sufficient rigidity.

Either way you will need to compensate for the additional thickness and don't forget about the increased weight.

By the way is anyone able to see the pictures I posted?

I ended up tearing out a section that seemed to be the worst and believe it or not the foam was not smashed like I thought it would be and the two pieces of quarter inch plywood were still glued quite well. It just lacked support underneath. I'm sure when it was new 16 years ago it was nice and firm. I ended up putting wooden floor joist from side to side every 12 inches. This was my first time attempting anything on a camper like this. And I'm going to tell you it was extremely difficult and sweaty and nasty. I will never do anything like it again. Since my kids are older and moved out I had no help cutting so I imagine I made 1000 trips up and down from underneath that thing! But it did help stiff the floor tremendously my only concern is when I hook it up and go down the road does the frame flex and twist slightly? Maybe it doesn't matter much just a concern.

We had a water leak in our Rockwood Roo HTT. Water came in from the bottom of one of the storage compartments that wasn't caulked from the factory. After replacing the wood and foam, I bolted 3 2x4s to act as I beams where the floor was replaced. Our HTT was already very low on CCC, so went with wood instead of steel. It helped a little, but the floor was still soft. Once the vacuum of the initial install is broken, the floor will be soft or spongy.

Our Roo's floor had 12 inch centers. I think if I had run a bolt through the aluminum sub-frame into the 2x4s, the floor may have had a little more rigidity. I didn't think about it until after I put the vinyl floor back down and I didn't want to have to redo it again.

-Michael

gafidler wrote:
2009 Rockwood Windjammers have the same floor problems, Manufacturers produce these to sell , not for people to use.

Rockwood started, at some point in the last few years, putting the aluminum tubes in the floor lamination on closer centers, and adding additional reinforcement at the areas that tend to fail. That's usally the high traffic areas such as in front of the sink cabinet, the toilet, in front of the entry door etc. Then midway through last year which would of been the 2017/18 model year they evidently eliminated the laminated floors across all lines, and went to plywood (probably OSB I would Imagine). I had read that elsewhere despite not seeing one in person and it still being advertised as 6 sided laminated construction. They also still show details of a laminated floor in the brochures and websites.