Floor insulation - needed?

[crispyboy]

I think I have a legitimate question about floor insulation.
Is it really needed?
When I pulled the rear of my trailer apart where water was getting into the belly pan and of course rotted the floor the original insulation had been wet also.
The outriggers were also very rusted due to the insulation holding in the moisture.
After I repaint/fix this area - is there really a need to put insulation back in the floor? It really bugs me to have something up against the steel frame that holds moisture.
My camping will be from March - November. These will include some cold
evenings. The grey tank is in the belly pan but the black tank is above the subfloor.
What do you all think?

[Shacksman]

I don't add any insultion in the floor when fixing a trailer. I don't see how 1 or 2 inches can do any thing worthwile compared to the mess the mice can make with it. Any I have taken apart had the insulation all bunched up in the belly pan and wet. Useing a carpet runner seems to be plenty when camping in cool weather.

[Aerowood]

I'm using 2 inch ridged blue foam glued to the bottom of the new floorboards

[crispyboy]

I've thought about the bubble wrap that some are using and but I would need to fasten/glue it to the floor. This seems like it would keep the wood from breathing - able to release normal moisture/humidity.

[Wabbiteer]

I can imagine an Airstream w/ no underfloor insulation - that is no fiberglass the factory crushed between the flooring sections and frame. Its just turned into pink sand water wick after 35 years. There were two layers of plywood missing from dry rot above the ladder frame in last three feet of my trailer; keep the trunk, taillights and wrap seals well caulked!

Having bought the wrong trailer <koff> I went on a clean campaign thus after peeking beneath the floor the subsequent escalation into a belly-off rehab is still ongoing... Besides POR-15 or Rustoleum painting all metal surfaces I also used Kilz sealer on all exposed plywood in between ladder frame rails, intending sealing the rest (except 4" band near edges) when I get outriggers welded in.

I used vulken-type caulk and monel staples to hold 1/4" foil-foam-foil insulation against flooring in between frame spars. I cut two-inch strips of same foam and followed the outline of each floor panel space then added doubled thickness center strip; gives some dead airspace and provides some drain ability if liquid water gets inside it. The caulk went on as continuous bead at edges of foam sheet so low/now moisture penetration.

I am now replacing the rear floor segment, and the 1/4" foam just fore of the BW tank I installed last fall was quite gnarly when I was trying to remove it... very effective installation and adds some sound proofing since an uninsulated belly will resonate sounds and vibrations like a snare drum...

[brown bear]

I am also replacing the floor in the bedroom of my A/S. I am thoroughly confused about the best way to re-insulate the floor. I really need some sound advice from those of you who have -been there, done that. I have found some holes in the floor pan near the cross members of the frame. Some of these look drilled and others look corroded. Do I need to fill these holes or leave them alone? What about caulking in and around these areas. This is all new to me. It all started when we decided to replace the carpet and found the rotted floor under the queen bed--the rear storage is located under the head of the bed. HELP !!!

[thecatsandi]

The newer trailer have a plastic bubble insulation. I had them put more in when the had to drop the belly pan. THe floor is cold when cold outside...

[1963tradewin]

I just put pink foam board in between floor and belly pan and foamed it in place so that air could still get thru I would say dont ever replace fiberglass insulation foam is better for weight, does not absorb water and is a much better insulating material good luck man

[brown bear]

63 tradewin, is this foam board the same thing as the blue boards that are in this area? Did you have any holes in your belly pan? Thanks, Brown Bear

[1963tradewin]

same foam just different company have holes in belly pan need to replace still but I hear there are suppose to be some holes for ventilation

[1963tradewin]

What Im going to do is put small vents riveted with aluminum that face backwards on the belly pan so if your driving in rain it will have a tougher time getting in.

[Wabbiteer]

Without studying the turbulence one will likely be scooping up spray - If it were beneficial Airstream Corporate would have instituted it across the board years ago. I don't even want to think of live ice-melt chemical or fertilizer residue mists, or road-kill chaff getting inside skins...

If you have to have vents how about go with access ports cut into skins w/ bug-proof screen mesh backing, plus a swing-away weather baffle that gets secured shut when moving. As provided there is finite air-space under floor so if you vent it you could actually be increasing the water condensating out onto interior metal surfaces since there is usually a lot of vapor-pressure of humidity rising off the ground which could set up a neat dew-cycle of its own inside the belly skins. Having access ports with swing away covers like an old lock's cylinder-keyhole guard might give the best of both worlds...

Seal the shell as best as you can, make sure tank and line drains drop water onto street instead of in shell, use non-absorbent insulation, leave belly skins not caulked, some dissimilar metal protection on spars and outriggers where skins will touch...

[thecatsandi]

This is what the do in airplanes and boats. Reverse scoops. Lets the water run out but not in.

[LI Pets]

I stripped all insulation out from under the floor, then put 1/4" foil bubble on top of the floor which also made a perfect base for Pergo, two birds one stone.

This bird has R 14 feathers.