Insulation on Ceiling

[weeeee]

... done lots of cold weather camping to -20 C.

Heat helps to minimise interior sweatting; I use a boat propane heater that has served me very well. Its a sealed unit so all intake and exaust is to the exterior.

CT Insulation / finish - The ceiling is insulated 1" ridged blue foam insulation (or was it 1/2 in; whatever max I could insall betwen the ribs; I didnt want to loose any head height). It has worked well; I would have installed thicker but I didnt want to loose any head height. The finished material was 1/4 good one side exterior sheathing ply; sealed with polyurithane; screwed in place with self tapping wide and heavy headed galvanized screws. This is covered with finished strips of oak trim again sealed with poly -U. Walls have 4" fiberglass batten insulation with 3/4" & 2X3 firring strips with 3/8" & 1/2" ply.

I notice minimal sweatting as the screws have a second layer of oak trim on top; also the firring strips offset direct screw contact and the poly -U acts as a vapour barrier; as suggested above. I notice the most sweattingin the interor around doors where the metal is still exposed ... check my pics for a better description.

Did you use any vapor barrier on walls or ceiling, or just using the sealed plywood as the barrier?

[mskobier]

All,
I am watching this post with much interest. I am currently in the process of converting my own 7x16. I have room for 1-1/2" of insulation on the roof. I am considering filling the void space in the ribs with expanding foam to help cut down on the sweating issue. I understand metal (steel) conducts heat, but with the ribs filled with insulation, the only heat transfer (theroetically) is the actual heat transfer through a strip of metal apprix 1/16" thick. To reach the inside, the heat would have to conduct through a thin strip a couple of inches long. Without the insulation, the entire metal rib is exposet to the heat sink of the aluminum skin and the cold air caused by it. I guess tha question is, is filling the ribs with expanding foam worth the effort? It doesn't look like it would be to much work to accomplish filling the ribs. From reading the many posts, most of us fill the ribs in the walls with foam, why would we not fill the ceiling ribs too?

Mitch

[GPW]

The more you fill in the better the insulation .... I don't know why we couldn't just get the whole inside sprayed with foam ... like houses... certainly would insulate everything , and add a good bit of rigidity to the surfaces... Makes it very Quiet too ...
We did Kustom Vans like that in the past ... made a Great job ... Pricy , unless you can make a deal ...like taking the trailer to a site where they're already spraying foam ...

[Prem]

I don't know why we can't just build single wall camping trailers and tow them to the trailer park behind the hotel in Puerto Escondido, Oaxaca, Mexico and hang out with all the Canadian RVers under palm trees while a warm ocean breeze blows over our skin.

[GPW]

For that kind of weather , might as well have a lean to ...

[Prem]

I may not have mentioned this before, but when I built the Featherlite, I insulated with rigid foam and put 1 inch-wide, thick felt tape the entire length of each aluminum rib in the walls and the ceiling. That meant that the plywood paneling would be against a soft surface, not metal. I attached the 4 x 8 ft. sheets of thin plywood with aluminum rivets using SS washers also. The rivets sucked down on the paneling and the felt tape beautifully.

I don't know why, but the rivet heads never "sweat" in cold weather when I'm heating the inside. Since the only metal inside the walls is aluminum, nothing is rusting.

For what it's worth.

Prem

[Engineer Guy]

Prem ~

I'm always looking for new, offensive material.

I insulted with rigid foam

So, just how does one insult with rigid foam? Reminds me of the classic line from Monty Python in 'The Holy Grail': 'I f**t in your general direction'! Great typo.

[Prem]

Engineer Guy,

insulated, insinuated, insulted...I type too fast. That's when I become "vowel challenged."

Sorry. I didn't mean to insulate you.

Prem

[BC Dave]

... done lots of cold weather camping to -20 C.

Did you use any vapor barrier on walls or ceiling, or just using the sealed plywood as the barrier?

Just catching up today ...

The ploy urithane sealer acts as a vapour barrier; seal all sides/edges; expecially the edges on plywood; it wicks moisture if you dont.

[Prem]

Best edge sealer for plywood: Bondo.

[BC Dave]

Best edge sealer for plywood: Bondo.

oh ... and I got sealing the edges from Perm after I didnt; he's the expert; with many good tips.

... I saw snow in Van for the first time today; we should all be packing and heading to Mx ... sigh.

[GPW]

Prem , not to be argumentative , but Bondo ??? I'd think I'd want something to sink waaaay into the end grain ,filling up the little tubes and spaces between ... more "encapsulation" ... Bondo would be Perfect for a final "cap" and filling voids ....
Sorry, it's just that it's so WET here , I always have to obsess about water intrusion ...
Inner door cores on my new (for me) Mini CT are ply , the bottoms untreated , and now soft and de-laminated ...grrrrr!!!! Going to try 75/25 mix and severe clamping ... and the Bondo sounds like a good idea for the edges... Thanks !!!

PS, I have a door frame on my house with a little rotten piece on the bottom , that I'll be using your Bondo Jedi trick on too ... Big Thanks , that saves me from having to sister in a new piece of wood which eventually do the same thing ...

[Prem]

GPW,

Ideally, you make your own bondo-like paste with epoxy and micro-spheres and silica, put on a yellow dish washing glove (tough rubber) and drive the paste into the plywood edge with fingers and thumb. Leave the edge slightly mounded up, domed with bondo.

Then you coat each sheet on the front with fiberglass cloth and coats of thin epoxy resin in 80+ degree heat. Coat the back of the sheet with two thin coats of epoxy. No water gets in. Sand the outside lightly, then wipe with a rag dripping with acetone to remove the waxy amines that came to the surface when the epoxy hardened. Paint with automotive acrylic enamel. Very durable. Might outlive you.

In the alternative, Bondo (tm) from the store is polyester resin with micro-spheres and silica. It's much cheaper and pre-mixed. It flat out works if you apply it by hand using the above method. 25 years ago, I was in the sign business. A couple of those signs are still up around here and their edges have not let go yet. No delamination, even though water vapor can penetrate polyester resin slightly. Go figger! It works. It must be the thickness of the paste that keeps the moisture out.

If you use polyester Bondo, you can stay cheap by just using automotive acrylic enamel sealer on the sheets front and back. (Don't use Thompson's Water Seal. It's got silicone in it. Paint won't stick.) Paint with cheap enamel from the hardware store. Every couple of years it will need sanding and a fresh coat.

Prem

[Prem]

BC Dave wrote:

from Perm...

Again? What did I do to deserve this again?

Repeat: I've never had a perm in my life.

[mskobier]

GPW, All,
Sorry to hear about the water damage to your door. However, there is light on the horizon on how to repair that piece and never have to worry about it again. There are at least two products on the market that will "fix" your problem. For people who build and repair wooden boats this will not be new news. The first product is called GIT ROT. I do not know who makes it, but it can be purchased on line or from your local marine dealer. The second is called Penetrating Epoxy and can be purchased from West systems. There are other similar products by other manufactures too. These two I have personal experience with. Basically, they are all a very thin two part epoxy which is designed to wick in and fill the voids/pores on water damaged wood. I have used both products and all I can say is that they work!. I had to do an in place repair to the floor of an old motorhome I once owned. The water system had been leaking for quite some time and had severly degraded the floor under the water tank. I could push a screw driver all the way through the floor fairly easily. Now normally this amount of damage would have been the end of the moptor home. There was no way to remove the existing floor without destroying the motorhome. I had heard about the GIT ROT from a wood boat builder friend, so I ordered a quart kit from the local marina. When I went to order it, the people at the marine didn't have a clue as to what I was talking about, but we found it in their catalog. Anyway to make a long story short, I mixed up the GIT ROT and poured it on and let it soak in. It took about 24 hrs to set up. After it had set up, I could stand on the bad area and jump up and down and the floor was solid. 15 years later when I finally got rid of the old motorhome, the floor was still solid. I also used it to repair a water damaged portion of particle board flooring in a mobil home I once owned. The warer damage was in front of the sliding glass door and the floor was very weak. Mixed up the penetrating Epoxy, poured it on and let it soak in, came back a day later, and the particle board was so solid, I could hardly drive a finishing nail through it to install the molding. I ended up drilling a small pilot hole for the nail to go through. I eventually replaced the floor, and I literally had to chissel that section of floor out. Anyway, for a water damage repair, I would not hesitate to use one of these products. Especially since that is what they were developed for. They do smell like Epoxy when they are curing, but that smell goes away in a couple of days and you are left with a repair that will last a long time. For the delaminated plywood, I would mix up one of the products, soak the area where the damage is, wrap the repaired are in poly plastic (epoxy will not stick to it), clamp between a couple pieces of board with several clamps to ensure even pressure and go away for a couple of days. Afterwords, remove the clamps and plastic and reinstall your door. Should last the life of your TT.

For treating the edges of plywood, I would think that these products would also work well. Again, that is what they were developed for. To seal and strengthen wood.

Another use for these products is stripped out screw holes in wood. Mix a small amount. Plug the striped holes with sawdust or small wood stick. Pour on and let soak in. Come back in a couple of days and drill new screw holes. The repair will be a lot stronget than the original wood and should not strip out again.

Anyway, I hoe you find this information usefull.

Mitch