Sub floor

[Krohsis]

Does anyone know how thick the sub floor is on these coaches? And do you know what the sub floor is composed of? Is it a single product like plywood, or is it sandwiched with something else? Thanks for your help.

[howson]

Does anyone know how thick the sub floor is on these coaches? And do you know what the sub floor is composed of? Is it a single product like plywood, or is it sandwiched with something else? Thanks for your help.

I'm not a lawyer, but the answer to, What is the subfloor is composed of? is It depends.

I'm going to get some of these terms wrong, but my Reflection travel trailer (maybe all of the TTs?) have a laminate sandwich-type floor that is pre-built prior to installation on the frame on the assembly line. To my untrained eye it looked like a wall that was being used as a floor. The insulation is foam, not fiberglass.



A fifth wheel--all of them I think--from Momentum to Reflections, have a frame with fiberglass insulation with OSB(?) laid on top. Again--I may not have my terms exactly correct. I'm not 100% sure on the thickness. I'll let someone else provide that information.



Again, not sure if I have the terms exactly correct and I don't know why there are the two different types of floors. From my single time looking at the difference on the factory floor, all I know is the floors are indeed quite different between my Reflection TT and a Reflection 5vr. Maybe one of my fellow moderators knows why there are two different floor constructions or one of the other owners here has more info to fill in the "why" behind the "what". If no one knows I'll ping Megan for more info.

-Howard

[Krohsis]

Thanks for the reply, Howard! So, I'm guessing you likely don't know the thickness of the wood used in the above sandwiched floor product? Is there a manufacture GD uses for this floor product that I could check with them and save you from spoon feeding me info ? I know you likely have better things to do than that.....

[howson]

Thanks for the reply, Howard! So, I'm guessing you likely don't know the thickness of the wood used in the above sandwiched floor product? Is there a manufacture GD uses for this floor product that I could check with them and save you from spoon feeding me info ? I know you likely have better things to do than that.....

I'm guessing GD makes the sandwiched floor themselves in their laminate manufacturing facility. I could be wrong. TucsonJim or Cate&Rob will probably know. I expect they (or another informed member) will chime in soon.

[Cate&Rob]

Krohsis
Which Grand Design model are you asking about? Floor design is different for different models.

Howards description of laminated "wall type" structure is true for Reflection 150 Series and TTs (except maybe Transcend). I don't know the thickness of interior floor laminate, but it is supported by the rigid foam insulation, so can be thinner (and lighter)

Reflection 5th Wheel and bigger use the other floor structure that Howard describes with the fiberglass insulation. Because the fibreglass offers no structural support to the floor between beams, the flooring has to be heavier and is a continuous sheet of (5/8" I think) OSB.

Rob

[Krohsis]

Rob, we have the 315RLTS travel trailer. So do you know how thick the wood on the outside of the sandwiched structure is? Thanks, John

[howson]

Rob, we have the 315RLTS travel trailer. So do you know how thick the wood on the outside of the sandwiched structure is? Thanks, John

Besides curiosity, is there a specific goal behind knowing the thickness of the flooring? What are you attempting to do?

Obviously I have a 315RLTS, too, but I do not know the thickness of the floor panel.

[Cate&Rob]

Besides curiosity, is there a specific goal behind knowing the thickness of the flooring? What are you attempting to do?

Obviously I have a 315RLTS, too, but I do not know the thickness of the floor panel.

Hi Howard,

Is there a hole in the floor of your 315RLTS where you can confirm the floor panel thickness and the insulation underneath? If the insulation is rigid white foam, I would expect the flooring to be relatively thin. If the insulation is fibreglass batt, the flooring will be about 5/8" thick OSB.

Rob

[howson]

Is there a hole in the floor of your 315RLTS where you can confirm the floor panel thickness and the insulation underneath?

There was--but I filled all those spots up with foam. One is under the sink where the water lines are and the other is behind the fireplace where the electrical comes up through the floor.

I looked through my pictures but couldn't find anything definitive. Definitely don't have anything that has a measurement.

Edit: Removed pics of fireplace removed as that is in the slide--not helpful for this thread.

[Cate&Rob]

I found this picture of the floor structure in my Reflection 303RLS 5th wheel. (this is in the underbelly on the main floor level where the shower drain goes into the grey tank.) You can see the 5/8" OSB floor and the fiberglass batt insulation underneath.

I am not a big fan of fiberglass insulation in a floor. Any water leak will be absorbed by this "sponge" which is then very difficult to dry out. I would much rather have the rigid foam which is reasonably water proof. But, I digress . . .

Rob

[Krohsis]

The area I'm working with is where the subfloor extends outside and over the wheels of the coach.

We just got back from our first trip with this coach. It was a long trip of about 4,000 miles over 3 1/2 weeks. During that trip we got into 2 rain storms that had us driving all day in heavy rain. Once home, while doing some routine maint on the coach, I noticed for the first time there is nothing between the subfloor and the high pressure spray coming off the wheel in the rain other than a thin layer of fabric. This fabric looks pretty worn where it was in the road spray for the trip. It looks like the fabric will be compromised with much more driving in the rain. In fact on the right side rear wheel, there is a very slight pinhole in the fabric. This is the first coach of 7 I have owned that has not had sheet metal in the "wheel wells". Even 2 cheaper rigs had sheet metal at this location.Clearly this is a poor design by GD.

My plan is to put a sealing coat of some sort on the fabric (undecided as to which product), then install sheet metal above the wheels and forward and back where water is slung off. I will screw the sheet metal to the subfloor and then caulk the seams.

So, that is the plan unless you gurus have a better idea. I have solicited some ideas on other forums, but most of them I'm not satisfied with as a good fix. Most have to do with either a spray on solution or putting things like eternabond there, etc. All of which are less than ideal for a number of reasons, but for one, the weight of the suggested application likely will just have the fabric let go of the subfloor and ultimately fail.

Now you have the whole story.

[Country Campers]

Krohsis

The sub floor that you are speaking about is actually the floor of the coach , I believe that this is either 5/8" or 3/4" thick on the Reflection line. The part of the floor that you are mentioning does not move with the slide. I have seen this "problem" mentioned before and I have thought about doing this as well. Installing some kind of sheet metal or even "fenders" up above the wheels on our unit. The plastic that you are seeing is not the "best" solution but is "ok". I am not sure if a spray on liner would be the best or not. If the plastic would be removed and then a spray on liner of some kind installed directly to the wood might be better than spraying on the plastic. I am curious on which route you take as I would like to something there as well. I believe that Jim TucsonJim , has done a mod like this maybe he will post with a description.

Brian

[howson]

The area I'm working with is where the subfloor extends outside and over the wheels of the coach.

OK--now I understand what you're asking.

I had to run out and look at mine. I've put >18K miles on the trailer and those locations look fine. The only complaints I've read is when a tire blows and the flapping rubber obliterates the underside of the trailer. Unless you build a tank frame under there, a flapping tire is going to tear stuff up.

Brian, Country Campers , is much more knowledgeable as he's a machinist. (I hope I got that term right!) I'm sure he'll chime in here soon.

-Howard

The first pic below has a red outline where I believe you want to reinforce against road debris--right? The other pics are just to show you the condition of mine after 18K miles.

[Krohsis]

Howard, yeah yours looks pretty darn good. If I had to give a life left in mine, it is over 75% worn from the water action on it. Some close ups of the fabric in the pics below . Definitely needs added protection.

Country Campers, I called it subfloor, using house terminology, but yes it is the floor of the RV and no it is NOT the slide at all. I just need to know if that flooring is solid plywood at that location or if it is some sort of sandwiched system like the pics Howard posted above. If it is solid plywood I will go forward with some sort of sheet metal in that area.

[howson]

Krohsis -- a couple of considerations if material is added to this area: 1) Provide a way for the area to drain and dry. Trapping moisture here could be bad! 2) Watch the clearance between the top of the tire and the trailer. For this latter point, I defer (again) to others as I know it is a critical consideration but not how to determine what is "enough". Cate&Rob ?

I'll be very interested in what you come up with--please update this thread as you go forward.

TucsonJim -- as Country Campers mentioned, didn't you do something in this area on your 297?