Insulating a new trailer

[sed8ed]

So after browsing here for a while, I have an idea as to what to do to my trailer in order to convert it properly however, I have a few insulation questions that I haven't been able to answer.

I am planning a 3 week trip up from Vancouver BC to Alaska (dropping the trailer in Fairbanks and driving to Deadhorse and back... Highest point in NA you can drive) plus I will be using the trailer for accommodation when I go hunting, fishing, quadding etc so the trailer MUST be 4 season friendly.

First question: Insulation material, why rigid extruded polystyrene over closed cell extruded polystyrene? Is there any major benefit over paying 3 times as much for the pink board vs the white stuff?

Second: the trailer manufacturer built the trailer walls like this, sheet metal skin - 3/8 ply - 1" square steel framing 24" on center - luan
When I insulate the trailer, do I have to worry about moisture getting between the wood and insulation and rotting the wood? What can I do about this?

Third: I was thinking of using 1 1/2" insulation, trimming the edges and using 4 inch wide strips of wood, screwed onto the frame in order to avoid heat transfer kinda like this: http://i273.photobucket.com/albums/jj20 ... onidea.jpg
Black is the 1" steel frame, blue is the insulation and yellow is the wood strip... what are your ideas on this?

Fourth: How do I insulate the floor without raising it? I was thinking of putting 3" closed cell underneath then boarding it off with 3/8 pressure treated ply but what about moisture getting up in there? What if I were to get the spray insulation guys to spray insulate it instead? How should I protect the insulation other than with 3/8 PT ply?

Thanks for all your help.

Here is a joke for your time:
A young man from Minnesota moves to Florida and goes to a big "everything under one roof" department store looking for a job.

The Manager says, "Do you have any sales experience?" The kid says "Yeah. I was a salesman back in Minnesota ."

Well, the boss liked the kid and gave him the job. "You start tomorrow. I'll come down after we close and see how you did."

His first day on the job was rough, but he got through it. After the store was locked up, the boss came down. "How many customers bought something from you today?"

The kid says "One".

The boss says "Just One? Our sales people average 20 to 30 customers a day. How much was the sale for?"

The kid says "$101, 237.65".

The boss says "$101,237.65? What the heck did you sell?"

The kid says, "First, I sold him a small fish hook. Then I sold him a medium fishhook. Then I sold him a larger fishhook. Then I sold him a new fishing rod. Then I asked him where he was going fishing and he said down the coast, so I told him he was going to need a boat, so we went down to the boat department and I sold him a twin engine Chris Craft. Then he said he didn't think his Honda Civic would pull it, so I took him down to the automotive department and sold him that 4x4 Expedition."

The boss said, "A guy came in here to buy a fish hook and you sold him a BOAT and a TRUCK?"

The kid said "No, the guy came in here to buy Tampons for his wife, and I said, 'Dude, your weekend's shot, you should go fishing.' "

[8ball_99]

The white stuff is expanded foam. The blue and pink stuff is extruded foam. Extruded foam is harder because the air gaps are smaller.. Since they are smaller it has more of them which gives it a little higher R Value.. So for the most part people use it because it gives you a better R for the same thickness. Also the price isn't that much more..

On your other questions.. Not 100% thats a little different then trailers I've seen.. Most have the sheeting attached to the studs or maybe a thin layer of thermoply between them.. Then they have 3/8s ply on the inside. My guess is as long the walls can breath you will be fine.. If you have a leak then the ply under the skin will probably rot.. But if the wall can breath atleast condensation shouldn't hurt the ply.. The strips of plywood under the luan inside should work well for a air gap. What I'd do is insulate the walls with 1" foam Then add 1/2 plywood strips. insulate between them then install the luan..

[OverTheTopCargoTrailer]

Hi Sed8ed

If you want to insulate for very cold or very hot temp, with min use of a/c or heating then you really need to build a BOX...inside of a box.... 2 complete layers of insulation. Insulation R valve is 66% and air leakage is 33%, of the equation, that is what most people don't understand. You can have R50 but if you have lots of air leakage, you don't have jack ! If you have high humidity , then use a dehumidifier (( they also make lots of heat )

my blog should give you some ideas, but a metal CT does not work like a house...The steel picks up & gets rid of the heat like water flows through a water line. That's why all RV are made out of wood, easier to insulate.

http://overthetopcargotrailer.blogspot.com/

also read this thread

http://www.tnttt.com/viewtopic.php?t=44903

Keep us informed what happens

[sed8ed]

OverTheTop - I actually have read your blog and that's where I got the idea for using 1 1/2 insulation and strapping 7/16 OSB on top of the studs (frame members) to both anchor the insulation in place (while giving me another wider surface to nail the luan to) and to create a barrier between the metal and the interior of the trailer.

As for using Rigid insulation over the closed cell, I get a rating of R5 per 1 inch of insulation and a 2x8' sheet is $15.99 at HD and it is unfortunately precut on the edges for layering. I need 16 sheets, I am going to check around at some of my construction sites to see if I can procure some from the insulators at a discount

Closed cell is what the RV dealer that I got my trailer from recommends, they build all their trailers with this: http://www.plastifab.com/TechnicalLibra ... oducts.pdf I am going to call them tomorrow and ask them what they suggest.

The High density closed cell has a rating of R4 per 1 inch of insulation, is recommended for direct burial and only costs $5.49 per 2x8' for the 1 inch and $7.49 for 1 1/2 which is the way I think I want to go between the two thicknesses

Between the 7/16 OSB and the metal, I am going to put 3/16 foam sill gasket in order to increase the insulation around the metal and to create an air gap between the luan and the insulation

We shall see tomorrow weather I go with rigid or closed cell depending on what the insulators say.

Any ideas on how to insulate the underside? I am going to check tomorrow as to how much it will cost to spray insulate underneath and then board off with 3/8 pressure treated ply however if I cant do spray foam, I think I will use 3" closed cell insulation instead but then how do I protect the wood from damage and rot? Undercoating?

[OverTheTopCargoTrailer]

Hi Sed8ed

The trick, the whole trick and nothing but the trick is, you said it !!!!
is to create a 2nd barrier between the metal and the interior of the trailer, so that the hot or cold steel studs can't transfer the heat.

Don't worry about this or that insulation R4 - R5 does not matter....
(the heat is transferred by the metal studs - RV's are built out of wood)
The one with the metal foil facing reflects the heat back inside.
Under the floor I used the 1" Home depot pink board & special fasterners



I would also use that for the floor inside as its very hard, then maybe 3/8 plywood over that to save weight.

I am also running all my wiring oversized , double fused and on the surface in wiremold. PLEASE realize, with all that foam, if that thing catches on fire.....The jiz is up !!! I am also limiting my wiring to the bare min and will use lots of LCD battery powered lights if needed. The heat produced by body heat and any appliances should heat the trailer pretty well. Remember 1 watt is equal to 3+ something Btu. And you body puts out at least 150 Btu per hour. It all adds up !!

[8ball_99]

The metal studs transfer heat, But the insulation still does quite a lot. Honestly I don't think campers are built from wood with climate control in mind.. They do it cause of cost. Wood is much cheaper and easier to build with. Insulate the walls best you can and but a decent layer between the metal and the living space. My ceiling has 1/2 strips on the studs with 1/2 foam in the gaps. But my walls just has 3/8ply with 1/4 paneling on top of that. That little bit of wood on the studs does help. On hot sunny days the walls don't feel any warmer then the air temp. I can heat my trailer with a 15 dollar bathroom heater and I can cool it with 9200Btu AC. Considering its 7x24 thats pretty good. Its always a trade off with insulation. Thats why our houses only have R13 or R19. R30 would be better but probably not worth the cost for the gain.

[OverTheTopCargoTrailer]

hi 8ball_99

We are just talking about heating and cooling the trailer with the min use of power , ie like boondocking or coyote camping, where maybe no power is available.

If one has a heater or electric power, then any little bit of insulation helps.
A white roof also does 10x more then the insulation to keep the roof heat out.
My temp dropped 15 deg F , just by painting the roof white for $25

Personally I hate the heat most, don't mind a little freezing so much.

[B@tt]

hi 8ball_99

My temp dropped 15 deg F , just by painting the roof white for $25

Wow! thats a HUGE difference. I had no idea painting the roof could do that much. What is the average temp you camp in? Its gotta be pretty hot to make that much of a difference.

[Pyrofish]

This is a pretty interesting topic, as I've been debating how I will insulate my roof for about month. Living and camping in Florida, the roof is a major hot spot.

What I'm considering doing is finding some of that screen-room aluminum 1" tubing. I plan to attach that directly to the 1" framing in the ceiling, running side to side, to give me a 2" cavity in which to put 2" thick foam. Then I'll run 1/2" plywood strip across that to hold the foam, and to attach the Luan ceiling. I think this will save me weight.

The foam is available at Lowes here for $26+ a sheet, but I may have a better source.

For the walls, I'm thinking something similar, but I need to get the wood off the walls prior to planning those. Now that the 4th of July is over, I can spend some time on it. Some of my camping will be 90F with only a Fantastic Fan on a 12v system... so I need some insulation. I wasn't going to paint the roof, but with those kinds of numbers, I think a bucket of elastomeric couldn't hurt