Belly pan?

[Cpardue]

Hi folks. I had a few questions now that I'm in pretty deep. I've removed the interior skins and old insulation from my 69 Overlander, and about a quarter of the subfloor. Some of the belly pan is missing below the aft section, and I'm considering removing all of the belly pan to better access the frame for rust treatment. My main question is: why do I need a belly pan? My tow vehicle doesn't have one. Does anyone ever leave it off? Just curious. It was full of all kinds of debris that was trapping moisture against the frame. I think I'd be better off without it. I know I would get a lot of water up there if I was towing in the rain, but it would eventually dry out. I'm considering epoxying the underside of the new plywood. Or using teak plywood. Has anyone tried teak?

[68 TWind]

You answered your own question- water.
Belly pan protects, insulation, wiring, floor, frame, from water and water intrusion into the inside thru all the holes in the flooring. Also helps keep critters out, helps with aerodynamics. I can't imagine not replacing or repairing the belly pan. Also, if you ever want to sell it, it will cost you a lot on resale if there is no belly pan. Sounds like you have done a lot of work, don't short cut the belly pan.

[Minno]

Teak is heavy. Consider that before using it. Would be pretty though.

Replace the belly pan for all the reasons 68 TWind gave you.

Chris

[Belegedhel]

Welcome to the Forums!

Yes, the belly pan does serve to keep most of the water out, but at the same time, they are never designed to be sealed and utterly water proof. They are also another barrier to keep out critters--they should be built tight enough to keep mice out. There is usually minimal electrical wiring under the floor, but the pan does protect it from physical damage. The 70's vintage trailers had the fresh water tank below the floor, so the belly pan protected that as well. Finally, the pan protects that nasty pink fiberglass under-floor insulation, which after 40 years ends up as a mass of nasty lying in the bottom of the pan. I think the biggest rationale for the bellypan was to give the entire trailer a smooth, aerodynamic skin.

There are a few threads discussing the merits of of going belly-pan-free. Try doing a google search from outside the Forums. Search for terms like "no belly pan airforums," and you might find some hits. To summarize from what I remember, there are some forums members who sealed up the underside of their floors, tacked on some closed cell foam board as insulation, or went insulation free, and went without. I believe there was some justification in that some models built today don't have a belly pan. Certainly most of the white box trailers have no covering underneath.

As far as floor materials go, there are many threads discussing the merits of using different materials for the sub-floor. There are several favorite and expensivce artificial and engineered plywood replacements, but for those who stick with good old plywood, the one thing they can agree on is that sealing it top, bottom and edges with poly or epoxy is a good idea.

Good luck!

[Lumatic]

Originally Posted by Belegedhel

Welcome to the Forums!

Yes, the belly pan does serve to keep most of the water out, but at the same time, they are never designed to be sealed and utterly water proof. They are also another barrier to keep out critters--they should be built tight enough to keep mice out. There is usually minimal electrical wiring under the floor, but the pan does protect it from physical damage. The 70's vintage trailers had the fresh water tank below the floor, so the belly pan protected that as well. Finally, the pan protects that nasty pink fiberglass under-floor insulation, which after 40 years ends up as a mass of nasty lying in the bottom of the pan. I think the biggest rationale for the bellypan was to give the entire trailer a smooth, aerodynamic skin.

There are a few threads discussing the merits of of going belly-pan-free. Try doing a google search from outside the Forums. Search for terms like "no belly pan airforums," and you might find some hits. To summarize from what I remember, there are some forums members who sealed up the underside of their floors, tacked on some closed cell foam board as insulation, or went insulation free, and went without. I believe there was some justification in that some models built today don't have a belly pan. Certainly most of the white box trailers have no covering underneath.

As far as floor materials go, there are many threads discussing the merits of using different materials for the sub-floor. There are several favorite and expensivce artificial and engineered plywood replacements, but for those who stick with good old plywood, the one thing they can agree on is that sealing it top, bottom and edges with poly or epoxy is a good idea.

Good luck!

I suspect the bellypan helps aerodynamically and also keeps road dust out of the coach.

[Tbeck11931]

All the above comments plus Another reason for the belly pan is to help protect your tanks and plumbing from freezing.

[perryg114]

I ran without the back portion of mine for a while. If the floor is sealed with urethane and the frame is painted and all the stinking pink wet insulation is gone, then you can go without it. It probably helps with gas mileage. I put mine back on but I used thicker material .032 and 1/4-20 screws. I like access to stuff for inspection and maintenance. I HATE HATE HATE pop rivets in areas that need periodic access.

Perry

[mikextr]

I found the amount of moisture, dirt, mold, and rodent signs contained by my original belly pan to be quite disturbing. For that reason, I am sealing and painting the underside of my trailer and not reinstalling a belly pan.

[Cpardue]

Thanks everyone. I'm prepping the frame for painting now. I think I'm just going to seal the underside well and leave the pan off. I've read a lot of threads since I posted and I think that makes the most sense. I appreciate all the advice.

[Wingeezer]

I have often wished our AS did not have the belly pan - our several previous SO trailers did not have such an arrangement and I feel was more practical.

Apart from making access more difficult for repair work, I am forever having to re-secure the belly pan due to corrosion issues (Aluminum belly pan pop-riveted to steel frame members.)

In our case I have little doubt that the corrosion problems are exacerbated by our annual winter trip south which takes us on salty wet highways. The salt water finds its way into teh belly pan one way or another and is impossible to remove even though I do my best to wash it away when we arrive at our warmer destination.

I'm sure that even when it dries, the salt lays in there ready to be reactivated when more rain water is introduced - winter or summer.

I think too that the belly pan perhaps increases the rate of corrosion of the frame by perpetuating a damp environment inside much longer.


No doubt there are some advantages to the belly pan - aerodynamics I suppose being one, but I think the advantages at least for us, are out weighed by the disadvantages.

Our last SOB had a galvanized steel frame and the plywood floor was coated with some sort of undercoating material and for my money was a much better arrangement.

I too have contemplated removing the belly pan and re-insulating the floor with a different material. Not sure what you would do about the banana wraps or whatever they are called (the curved painted pieces around the shell perimeter - add some extra support for them?

Meanwhile I just keep repairing the belly pan sheet securement, and I fully expect to have more work to do this winter when we get to Florida!

This year I am taking a supply of larger rivets and an air/hydraulic rivet gun! Also going to try some self drilling SS hex head screws!

[featherbedder]

Originally Posted by Belegedhel

Welcome to the Forums!

Yes, the belly pan does serve to keep most of the water out, but at the same time, they are never designed to be sealed and utterly water proof. They are also another barrier to keep out critters--they should be built tight enough to keep mice out. There is usually minimal electrical wiring under the floor, but the pan does protect it from physical damage. The 70's vintage trailers had the fresh water tank below the floor, so the belly pan protected that as well. Finally, the pan protects that nasty pink fiberglass under-floor insulation, which after 40 years ends up as a mass of nasty lying in the bottom of the pan. I think the biggest rationale for the bellypan was to give the entire trailer a smooth, aerodynamic skin.

There are a few threads discussing the merits of of going belly-pan-free. Try doing a google search from outside the Forums. Search for terms like "no belly pan airforums," and you might find some hits. To summarize from what I remember, there are some forums members who sealed up the underside of their floors, tacked on some closed cell foam board as insulation, or went insulation free, and went without. I believe there was some justification in that some models built today don't have a belly pan. Certainly most of the white box trailers have no covering underneath.

As far as floor materials go, there are many threads discussing the merits of using different materials for the sub-floor. There are several favorite and expensivce artificial and engineered plywood replacements, but for those who stick with good old plywood, the one thing they can agree on is that sealing it top, bottom and edges with poly or epoxy is a good idea.

Good luck!

That nasty mess of pink gets wet rots floor and rusts frame as it does not dry.