Mounting through exterior wall panels

Maxcamp

I would love to mount some L-track hold-downs the length of the interior above the bed (behind backrest cushions.) 
This would allow us to strap down lightweight boxes of bedding, etc. so they cannot fly around as well as a certain piece of gear. 
However there is no meat to screw to. 

Wonder about sandwiching the sidewall Adzel panel between L-track on inside and a 3/32 x 1.5" wide aluminum continuous plate on outside to spread the load, using through-drilled 1/4" x ~1.5" flathead machine screws, washers, nylok nuts, and caulked penetrations perhaps 8" on center.  As this will drastically alter the appearance and create penetrations requiring sealant I wanted to get some feedback first.

Thoughts?  Experience with through-mounting of attachment plates?  Will this weaken the panel or lead to cracking?
Photo of L-track below:


NuCamp T&B 320S Boondock (mfg. Jan. 2021)/ Tacoma 4 cylinder tow in (sigh) low gears.

Marceline

I would not do that. The walls are a foam sandwich. Tension on that bar could cause compression, delamination or worse. 

I put everything on the floor and the last thing I put in the trailer is a big bean bag chair that I use to prevent load shifting. 

Denny16

If you have the plywood layer in your sub-floor, you could screw the tracks along the front of the bunks to the floor, or to the plywood fronts of the bunks.  I agree with Marceline, not to try and screw them to the trailer sides.
cheers

Marceline

Denny16 said:

If you have the plywood layer in your sub-floor, you could screw the tracks along the front of the bunks to the floor, or to the plywood fronts of the bunks.  I agree with Marceline, not to try and screw them to the trailer sides.
cheers

Or you could put an eye bolt/screw at both ends of the bench seats at the wall, run a cable between them on both sides, and then clip bungee cords or netting between the cables to hold things down for travel. With the cushions in place the cables would be hidden. 

Maxcamp

For sale... four 48" L tracks and sixteen clips, new unused. Would be terrific on pickup bed sidewalls/bed if you don't have a factory tie down system.

MuttonChops

side wall construction

https://tab-rv.vanillacommunity.com/discussion/7495/structural-information#latest         reference material

Maxcamp

fantastic.  EGS is electro galvanized steel I presume.  Certainly no ASTM structural tubes here, some forum photos show something that might be rectangular aluminum tubing in the 22 gauge range?  IE might hold and deform under a sheetmetal screw, not good for through bolts without fender washer perhaps.

MuttonChops

Maxcamp8 said:
. . . EGS is electro galvanized steel I presume. 

Yes, I believe that is the correct definition for the acronym (at least that is what Jayco says)
While I have not seen a cross-section of the EGS areas I believe it is a veryyyy thin metal layer, like a couple of sheets of aluminum foil thick.  It's function being to provide a bit of grip for screws used in those wall areas.

Maxcamp8 said:
. . . some forum photos show something that might be rectangular aluminum tubing
       in the 22 gauge range?

I do not know the tubing wall thickness.
Side wall exterior and window 'framing' seems to the 1x1 O.D. tubing.
The roof area has a more standard framing with 0.75 x 0.75 tubing along the top of the sidewalls
and 0.75 X 1.75 cross frames.

RCB

On boats with balsa cored decks fasteners can be successfully passed thru the deck to attach cleats or whatever.  The method I believe can be applied to the T@B walls. Briefly it is done as follows: the fastener must pass thru the wall from outside to inside. Drill a hole thru the wall; on the inside drill a larger hole 4 times the diameter of the bolt ; clean out the hole to the inside surface of the exterior panel; protect the inside surface with tape and fill the large hole with stiffly mixed epoxy; once set and levelled, re-drill the bolt hole from the outside; insert bolt with washer and whatever you are mounting should fully cover the epoxy plug on the inside - if not use a fender washer under.

Marceline

RCB said:

On boats with balsa cored decks fasteners can be successfully passed thru the deck to attach cleats or whatever.  The method I believe can be applied to the T@B walls. Briefly it is done as follows: the fastener must pass thru the wall from outside to inside. Drill a hole thru the wall; on the inside drill a larger hole 4 times the diameter of the bolt ; clean out the hole to the inside surface of the exterior panel; protect the inside surface with tape and fill the large hole with stiffly mixed epoxy; once set and levelled, re-drill the bolt hole from the outside; insert bolt with washer and whatever you are mounting should fully cover the epoxy plug on the inside - if not use a fender washer under.

Yeah but the foam sandwich of the T@B wall isn’t anywhere near as strong as a balsa core deck. If you laid it horizontally you couldn’t walk on it without wrecking it. If you made the epoxy plugs there would be a stress riser at the perimeter of the plug due to the very significant strength disparity between the wall panel and the plug. There is just no way I would do this. 

(FWIW I have rebuilt the sole of a small boat and rebedded the keel bolts using balsa and epoxy plugs so I have experience with this construction technique)