wall insulation

[ibbowhunting]

how thick does the wall insulation need to be to prevent condensation, what is the norm, walls,roof and the floor the same thickness also? I planned on using 3/4 plywood walls but I don't like the sounds of frost or condensation on the inside of my tear, I don't plan on winter camping but I bet there will be quite a few night below the dew point and some below freezing, I still would like to use one side of the 4x10 x 3/4 plywood as the interior finish, anyway this is possiable without making the tear super heavy but insulated

[Shadow Catcher]

Controlling condensation is in part about air circulation and not letting moisture build up in a very confined space. Our tear has an all aluminum frame including walls and ceiling with 1.5" EPS insulation with 1/8" interior and 1/4" exterior covered with Filon. In cold weather the ceiling fans (two Antec three speed case fans) are on low.
To a certain extent this does not answer your question, but from experience we get some condensation if the fans are not on and the vent open a little bit.

[tony.latham]

I've spent many a night in cold weather in teardrops with both solid wood walls and insulated sandwiched construction walls. Switching to a sandwiched-walled teardrop and the condensation issue is in my past.



To answer your question, 3/4" of foam in the walls will do the job just fine. Ventilation is still important but I've found that two doors vented about an inch and the roof vent cracked open works just fine with two aboard. Ceiling? Fill the structure out with insulation. Floor? I fall into the camp that if you're getting cold coming up through a teardrop mattress, it's not thick enough. Mine's 7".

I'd think that if you were going to insulate a teardrop wall, you'd just as well make sandwiched walls. I prefer a 3/4" plywood skeleton and 1/4" interior/exterior sheathing. Some use 1/8" I think, but that's a whole different thread.

Tony

[noseoil]

We "slept out" last night in the driveway for fun. It was about 34 outside for the low (Tucson winter, brrrrr). We have sandwich wall construction (3/4" ply skeleton & foam, 1/8" in & out wood skins, & .040" aluminum skin outside). Granted, it didn't get down to freezing, but the only condensation we had was on the door & window glass. Everything else is wood & there was no problem with drips. We use a 5" foam mattress with a 3" topper. Inside temperature was about 45 when we got up, so 2 bodies in a small space makes for a bit of warmth. Had the vent cracked open a tad in the roof for air flow, but no windows were open.

[tony.latham]

We "slept out" last night in the driveway for fun.

Hey, Tim: You guys really like your new 'drop, dontcha!

Now, back to the insulation thread.

Tony

[ibbowhunting]

ok so if I skeletonize my 3/4 plywood and install foam insulation how much wood, would I leave around the edges, doors, windows and bunkhead

[tony.latham]

ok so if I skeletonize my 3/4 plywood and install foam insulation how much wood, would I leave around the edges, doors, windows and bunkhead

Here's a 5 x 10 I did:



I think I was fairly liberal on how much structure I left. (Plus I ended up attaching the fenders to the chassis, not the wall). Take a look at Noseoil's build log. I think he nailed it.

Tony

[booyah]

We were out about two months ago overnight in 40F weather.

Build info
The tear is 3/8" external plywood, 3/4" R5 foam board, and 1/4" interior plywood. Floor is 1/2" plywood, with the same 3/4" insulation below.
Roof is 1/8" Baltic Birch outside, same 3/4" R5 foam and 1/8th baltic birch inside. Spars are 1.5" (1x2s pine) and there is a decent amount of air gap with the insulation in the roof.. Doors are foam core commercially made doors, with single pane glass and aluminum trim.

Ventilation
Window was cracked a little bit (bout 1/8th inch on each side) and the roof vent was open a little, but fan turned off. We were more concerned about warmth with a cold overnight than on ventilation.

Output
Condensation formed on the aluminum trim of the doors, the windows, and on the spars in the roof, but not on any part that was insulated. Interior was about 60F with two people inside and we were in normal jammies (My 11yo daughter and I). A little chilly, but otherwise just dandy. We slept under two normal household blankets, nothing fancy or especially warm (IE sleeping bags or special comforters or quilts).

Next time
If it were much cooler, I think an electric heater would be a good choice, and I plan on putting a 750w with thermostat I have on hand in there to test with the intent of moving a smaller one in there later (200-500w). I suspect 750w is WAY too much, and would be a heavy load for my little generator for when I'm in the boonies, but want to verify that before I end up too cold in the winter :-)