Worthwhile to insulate/enclose underbelly without heating?

[profdant139]

As I have mentioned in earlier threads, I want to do more cold-weather camping next fall and winter. But I am having a heck of a time figuring out how to heat an enclosed underbelly when we don’t have hookups (which is most of the time) – my furnace won’t do the job (no place for ducts), and it is tricky to use my water heater as a heat source, at least until my electrical skills are greatly improved. And heat tape is out of the question – it would draw too much current when we are boondocking. (So would the furnace, really.)

I am pretty sure I can beef up the insulation with Styrofoam boards, and cover the whole underbelly with coroplast. So that is my question – without a heat source, is that a project worth doing?

I do understand that inanimate objects don’t suffer from “wind chill,” so cutting down on the wind under the trailer by enclosing it won’t accomplish much. But if this project will even slightly cut down on the risk of freezing my tanks and my lines, that would be a big plus.

Your thoughts and advice are always appreciated!

[agesilaus]

Don't forget this point: insulation works both winter and summer since it makes your a/c more efficient. And keeps the rv cooler in summer with or without a/c.

[HadEnough]

Plumbing will definitely benefit from the insulation.

The heat escaping through your floor will, to an extent, help keep the plumbing from freezing.

[westend]

Any insulation that is installed under the floor is going to make comfort increase in a travel trailer. I've done three, so far. Keeping water lines, drains, and tanks from freezing is a tangent from insulating the under belly since you need some sort of heat to keep things from freezing (assuming parked or travel at a low temp). I'd suggest to consider some heat tapes or tank heaters.

FWIW, I have a tank/drain project for my trailer scheduled. I plan to enclose the single waste tank (maybe add a small grey tank) and all the drains right out to the drain exits. I will use 3/4 extruded polystyrene clad with aluminum sheets to enclose the areas. Heat will be supplied by a 60' length of gutter cable and a heat tape toward the outboard ends of the drain plumbing. All of this nonsense is inside a steel frame. The GFCI circuit with switched receptacle is already installed. It will allow me to camp at any temperature and be able to dump waste. A side benefit is that all of this is directly under my bathroom area and should serve to keep that floor warmer.

[profdant139]

Good points, Steve and SD -- even if I can't use the heat tape routinely, I should install it in order to thaw things out! I bet I could power that tape off my generator, when necessary.

[SDcampowneroper]

We lowered the axles screwed on 11/2 x 2 pvc brick mould to the frame. then 2" high density foam, then coroplast. The extra R 10 made all the difference on a rig we wintered over in Canada.
First
Heat traced all waterlines, used old waterbed heat pads on tanks ran them up to where they could be plugged into camp power or inverter.

Heat tracing isnot expensive with cut to length 5w/ ' SS cables. If you did freeze up,the tows alternator through the inverter, or shore power would thaw them quickly.

[Old-Biscuit]

An insulated enclosed area IS much better than a wide open area.

Even IF you do not provide a heat source.

[rexlion]

A dense, sprayed-on urethane foam insulation should not be able to ansorb water. It sticks well and is seamless. And it acts as a vapor barrier, which adds to the insulating factor, so less thickness is needed than other forms of insulation; this has been proven in such applications as potato storage in ID.

[agesilaus]

Styrofoam absorbs water? That's news to me. The stuff they sell as insulation board seems to be somewhat denser that plain styrofoam tho. But neither absorbs water so far as I have heard. Spun Fiberglass dies when it is exposed to water tho so I wonder if your advise is good. From the Lowe's website, the info sheet on insulation board:
------------------------------------------------------------
Specifically developed for wall sheathing, basement insulation, siding underlayment and foundation insulation

Excellent insulating properties and moisture resistance

[Lwiddis]

From a wind standpoint alone, I say yes, small as it may be.

[SteveAE]

Dan,

Yes, it will help.

I would suggest something other than "Styrofoam" though as, if/when water gets up there, Styrofoam will tend to absorb it. I used about 2.5 inches of spun fiberglass insulation (easier to fit around wires and plumbing) held up with 2" thick foam made to go below grade. Long screws with fender washers hold up the foam and all joints are taped. Reflectix type insulation under the foam and, finally, the corplast. As recommended by another forum member, I put drains in the Reflectix/Corplast so, if/when water gets in there (it will), there is a way to drain it out. Radiant heater above the fresh water tank keeps the floor warm and, via conduction, the tank seems to stay "warm enough". Of course, your layout may not allow for this.

Might want to wrap any plumbing down there with heat tape and foam pipe insulation so, if needed, you have a way of thawing it out.

Hope this helps.

[SoundGuy]

I've owned trailers with and without enclosed underbellies and never noticed any difference at all between the two. I'd suspect that you achieve better heat retention in cold weather by skirting the trailer with something like Reflectix that would prevent cold air from blowing under the trailer.