Building our box out of wood?

[MTVR]

You guys are certainly giving me some things to think about...

 

[MTVR]

So it sounds like I need to be able to heat/cool/dehumidify whatever volume of air we need to exchange, and we only need enough insulation for the relatively small amount of space that we are doing that in. Am I sneaking up on it?

 

[rruff]

I prefer to think of it as two different things that result in heat loss. One is heating up the ventilation air, and the other is what you lose by conduction through the walls/windows/doors. Insulation can only address the later. You reach the point of diminishing returns with thinner walls (lower R) than you'd have in a house.

 

[MTVR]

Okay, so if we use walls that aren't thinner than a house (higher R-value), then we would reach that point of exchange air heating/cooling diminishing returns later- is that right?

 

[IdaSHO]

Your overthinking it.

Don't concern yourself about household R-values.
They simply do not apply directly.

Think of your camper like an ice-chest, and build it as such.
You want it air tight and insulated well. Then apply venting as needed.

Yes, air exchange is critical, especially in lower temps.
But not to the degree that is being considered here.

With a small roof vent and cracking a window, we rarely have condensation issues, even in cold temps with two adults and two dogs.
ANY ventilation makes the concern a non-issue.

 

[rruff]

With a small roof vent and cracking a window, we rarely have condensation issues, even in cold temps with two adults and two dogs.
ANY ventilation makes the concern a non-issue.

We are discussing the merits of having 6" foam filled studs for the walls. The need for ventilation negates the benefit of high R in the walls. Yours are 1.5" thick...?

Okay, so if we use walls that aren't thinner than a house (higher R-value), then we would reach that point of exchange air heating/cooling diminishing returns later- is that right?

The diminishing returns are in the wall. "Optimal" wall R value in a camper will be less than it is in a house.

 

[IdaSHO]

We are discussing the merits of having 6" foam filled studs for the walls. The need for ventilation negates the benefit of high R in the walls. Yours are 1.5" thick...?

We are talking about a large camper, are we not? So no, the need for ventilation does NOT negate the benefit of high R in the walls.
Every time you increase the volume and surface area of the camper, the need for insulation increases.

BTW, these are the comments that I feel are a bit off the mark.
Again, yes, this is a consideration, but not to the degree these comments seem to make them.

You need a good amount of constant air exchange, and you'll need that regardless of how good your insulation is.

Instead of "good amount", Id suggest "enough"
Which, in my experience, is less than most would think.

you will need to constantly bring in fresh air, or it will get uncomfortablely humid pretty quickly.

Constant is not required, especially when most people remain in their camper at MOST for 6-8 hours at a time.
Every time you open the door you have a large exchange of air. "Constant" air exchange is not needed, unless you run the actual numbers...
Assuming a sealed system... number of occupants, volume of air in the camper, and hours.

Again, all from first hand extended use experience, in worst case weather conditions. A small amount of ventilation goes a long ways.

Don't over think it.

 

[1000arms]

The better the insulation (and sealing) of your camper body, the easier it is to maintain the interior temperature when it is occupied and UNOCCUPIED. (But too much insulation cuts into the small volume you are using as a living space. There is a balance.)

Going skiing/snowshoeing/snowboarding/.. and don't want anything freezing? Going swimming/hiking/... and don't want to return to an oven? Want to return to a comfortable camper when it is cold/raining/roasting/... ? Want to park your vehicle at home for a couple of weeks in the sun/cold/... and easily avoid cooking/freezing/draining/removing/... the contents? Insulation (and sealing) minimize how much energy is needed to maintain the camper within a temperature range that makes you happy.

if you do only a decent job of sealing, you WILL need fresh air when the camper is occupied. My guess is you will do much better than "only a decent job sealing".

I suggest you glue and screw your camper together out of wood, plywood, and rigid insulation. The materials are common, cheap (compared what a composite box would likely cost you), and fairly quick to put together (especially compared to the long build times of some campers). I suspect you are already familiar with the materials.

Because of your rig's capacity, you don't need to be concerned with every pound.

Build your camper and get out and use it. Too many DIY boat-builders spend years building their boats without using them, and some DIY camper builders do the same.

Build your camper as a solid, road/offroad-worthy, sealed, insulated, ventilated, heated and cooled tiny-home you can enjoy traveling in for the 5 years (or more) that you mentioned.

Keep your costs and your build-time down, and you can always remove your camper, sell it as a tiny-home, and mount your new and improved Mark II model.

 

[IdaSHO]

Yep, as i said....

Think of your camper like an ice-chest, and build it as such.
You want it air tight and insulated well. Then apply venting as needed.

 

[s.e.charles]

I have never installed or used one, but rumor is that a floor vent can offer some air ingress to assist higher apertures excavation of same.

but don't think too much about it*

*soon to be signature material

 

[Simons]

A lot of these comments about insulation are focusing on the cold weather benefits and moisture issues but I think your ideas of thick walls will really help you keep temperatures down in the warm weather months. Maybe also consider a foil backed insulation? You can always put another blanket on in the cold but you can only get so naked! Lol.
For the studs and roof trusses consider using plywood, you can build any shape you want. Cut it into a curved shape and create voids for the insulation to pass through. It’s thin thickness will drastically reduce any thermal bridging.
I’ve seen some very creative structures designed and built out of plywood using CAD and CNC. (or even pencil and jigsaw

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[Simons]

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[Simons]

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[Simons]

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[s.e.charles]

… be able to build it ourselves, without any special tools or skills.

… What do you guys think?

OP from OP

let's keep on the trail here