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Topic: An Easy Structural Upgrade For Basement Mounted Items (Read 1386 times) previous topic - next topic

An Easy Structural Upgrade For Basement Mounted Items

I just did a mechanical inspection on a really nice 320.  I want to mention one often-found item that can cause issues if left unattended, yet costs little to permanently fix.

Joey bed and hose/shore power reels often break the lower FG floor under the coach.  This can allow water to migrate in (unless you use the coach in the desert SW of course).

The reason for the failure is that you have a relatively heavy item that gets torqued (and therefore transmits that torque through the mounting bolts) mounted on non-structural area.  Remember, except for the box beams, the floor of the basement is a THIN sheet of FG, 1 ½" form and a THIN sheet of FG.  None of this, particularly if you don't spread the load, can handle the torque of a Joey bed locking into place with a couple of hundred pounds on it.  Same, to a lesser degree for the hose/shore power cord reels. 

For the reels, the solution is quick and inexpensive:  Use four 3"X3" sheets of 1/8" aluminum with a hole drilled in the middle for the through bolt as the "backing plates" below the reels.  Use a good sealant and torque up the through bolts.  You have sealed the area (covered any cracked or deformed FG) and have spread the load.

Properly addressing the MUCH heavier Joey bed is a little more complex.  Yes, you will use those same aluminum backing plates (I like 4"X4"), but you are still squeezing that foam core—not a structurally good idea.  So, get out your hole saws.  Using the existing mounting holes, from ABOVE (inside basement) drill through the floor of the basement-side FG with a 3-4" hole saw. Stop as soon as you punch into the soft foam core.  Use a screwdriver to remove the foam core.  Now, make a wood plug the exact thickness of the foam core and the same diameter as the hole.  If you have a good set of hole saws, often the next size up from the one you used to drill the hole in the floor will be a nice tight fit in the hole.  Inset it in the hole and through bolt.  Now, you are squeezing the Joey bed rail above (lots of surface) and the aluminum plate below (good amount of surface area), and you can now reasonably torque the bolts so that they carry the lateral load of the Joey bed slamming closed, as the wood plug will not deform as the foam did.

Sooo, take a quick look under the basement and see if those bolts have deformed or cracked the FG.

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #1 –
Great advice, Brett, and thanks for the solutions.  One of my reels has caused this problem, so this is going on the "to do" list.

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #2 –
On our 99 U270 with a full width double slide Joey bed, all of the bolts are going through the 1.5" square tubing. Before I did the basement rebuild, most of them were through the tubing but I relocated the few that weren't. They were meant to have been, just missed the tubing by a ½" or so ??? . The tubing is fairly thin walled (I believe it is 18 gage, 16 gage at the most), and so torque can be reasonably applied, but over doing would easily crush the tubing. I used approx. 3" square pieces of ⅛" SS flat stock to back the bolts from underneath and spread the load. They also served to cover the the few holes that originally missed the tubing from the original installation. They are glued on and sealed with 3m 5200 in addition to the bolts going through. If there is no framing where the JoeyBed mounts are, I like Brett's idea of using a couple of stacked discs of ¾" plywood glued together to take the place of the foam and spread the load to a larger area. Just to amplify this idea a bit, I would also want to bed the wood disc with Epoxy, as well as glue the  (Epoxy won't melt the Polystyrene insulation, especially if you use the slower curing type, but even the 5 minute will work). You could also use epoxy to glue back the round fiberglass plug that you removed with the hole saw in the first step. It will be slightly under sized because of the saw kerf, but filling the groove with some good polyurethane caulking will take care of that and seal it as well. Just my two cents... By the way, one trick I have used when cutting out a plug without going through the back side of the fiberglass is to start the hole with the hole saw as usual, and after cutting through the first layer of fiberglass, remove the pilot bit and continue with the hole saw to get close to the depth of the rigid foam insulation. Depending on how perpendicular you are able to maintain the drill motor, you can get quite close to the back of the fiberglass skin without scoring it and then it is very easy to dig out the remaining bit of blue styrofoam and have a nice clean hole to glue in a solid filler disc.
Don

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #3 –
Don,

Actually, the location of the Joey bed through bolts is generally dictated by the location of the holes in the Joey bed rails.  So the greatest likelihood is that they will be through foam, not the box beams.

And, yes I used epoxy (West system) to bed the wood disks on our U240.  But in reality it is just there to keep from squeezing/crushing the foam core.  Said another way, the friction of the Joey bed rails above and large aluminum backing plate below provide excellent resistance to the side load closing the Joey bed puts on the fasteners.  If one REALLY loads their Joey bed, then a 6" by 6" or larger aluminum plate would spread the load even more.

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #4 –
Could one of you who are more familiar with the basement floor construction answer a question for me? I'm considering installing a propane fired "endless" hot water system that requires venting the flue and air intake through the floor. How do I locate the framework  so I miss it when I cut the holes?
My coach is a 1997 U320

Thanks

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #5 –
Strong magnets make it a cinch to locate the basement framing. I use ones normally sold for locating electrical j-boxes behind drywall. using two of them and a straight edge makes it easy to locate the 1.5" square tubing and draw it with a sharpie marker. The one I use are called "Blind Mark". I bought them from one of the big box stores...
Don
Quote from: chazb11 –
Could one of you who are more familiar with the basement floor construction answer a question for me? I'm considering installing a propane fired "endless" hot water system that requires venting the flue and air intake through the floor. How do I locate the framework  so I miss it when I cut the holes?
My coach is a 1997 U320

Thanks

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #6 –
Thanks Don. Looks like a handy tool to have. I'll have to make a trip to the store if it ever stops snowing here.
 

Re: An Easy Structural Upgrade For Basement Mounted Items

Reply #7 –
Reviving Brett's post from 6 years ago.
We are currently installing hose and power reels in our coach.
The Joey bed will be inspected next.

VERY good info for some of us newer owners.