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Old 10-08-2015, 01:20 PM   #11
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Originally Posted by EastCoastCB View Post
Yes, I did see that thread, and it gave me a lot of hope that this idea was feasible. But on that thread, there were only photos of buildings. I have also seen people spray foam the outside of shipping containers with great results.

So I think the concept is sound.
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Old 10-08-2015, 01:41 PM   #12
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I'm having a real hard time imagining how foam on the exterior could last on a bus for more than a few weeks (?) Even if it were coated with something like Gelcoat or fiberglass. And trying to get a reasonable finish is a tough job even for a pro.
UV light would degrade both the spray foam and the rigid foam, so they would have to be painted with some sort of solar protective coating. The elastomeric coatings are designed to handle temperature swings, rain, and UV light.

The next concern is vibrations when driving. The spray foam sticks to everything and it can handle the vibrations just fine. Also, I only plan on driving the bus twice in 4 years, so I'm not overly concerned with travel. It wouldn't cost too much to repair, or even start over.

As for the finish, I only want to foam the roof of the bus which I doubt anyone will ever see. There are some specialty tools for smoothing spray foam. With those and a belt sander, I should be able to get the roof smooth enough to paint.

I do not want to foam the exterior walls of the bus, I think that would be much harder and would not look good. So my main concern with appearance is the bend between the roof and the wall. That part is visible from the ground.
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Old 10-08-2015, 02:02 PM   #13
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Thanks everyone for chipping in. It really helps to bounce ideas around. So far, I am convinced that insulating the outside, while not ideal, will still be worth the money. It should cost around $600 for the foam, and $150 for the solar elastomeric coating. So with a 4 year lifespan, it only needs to save me $15/month off my electricity bill to pay for itself. I think it will save me much more than that.

But one question that remains, is it better to go with rigid foam or spray foam:

Spray foam advantages:
-Sticks really well
-Proven technology

Spray foam disadvantages
-Higher cost
-More work
-Riskier/more things could go wrong
-Most be done all at once

Rigid foam advantages
-Cheaper
-Easier to do in sections
-Doesn't need smoothing
-Easy to find materials
-Easy to paint

Rigid foam disadvatages
-What kind of glue to use?
-How much does the glue cost?
-Will the glue still hold after temperature fluctuations?
-Do I need a special sprayer to apply the glue?
-Need to cut the foam to fit around the long metal ridges going down the length of the roof.


I lot of this discussion has leaned towards the spray foam, but I still think that the ROI of rigid foam would be higher. I would need 10-12 panels of 4x8 rigid foam at about $10 each. Even if I had to buy 20 cans of spray adhesive, the cost should be under $100. I might need to score the foam to get it to bend around the edges of the roof, and I might need to fill those gaps with Great stuff, but that shouldn't take more than 4 hours and should be fairly easy to trim. Then I could just paint over the whole thing. I would still need to apply insulation to the inside of the bus, but I think that spending $250 on outside insulation would really help a ton.

What are your thoughts?
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Old 10-08-2015, 02:03 PM   #14
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If you are going to use foam board you will want to use several thinner sheets of it with a layer of glue, plain old white glue, in between them. Foam and well many things are more flexible in thinner layers. Basically you want to make plywood-esque foam for the top. you will need to cover it in something or it will deteriorate in the sun. As for attaching it to the bus though I don't know what would stick to the metal and not melt the foam.

If I were to try to foam the outside of a bus I would probably get 1.5x.5 steel square tube and weld them to the roof 16 inch on center (wood 2x2 could work). Then spray foam in between. Cover that with metal roofing and elastomeric over that.

Quick question, how do you plan on using your skoolie? Is it going to be a non moving cabin or are you using it as an on the road RV? How long do you plan on using your skoolie for? Where do you plan on using this rig at?

You say it is only going to be driven 2 times after completion, how long are those drives going to be 50ft or 500 mi?

..shouldn't take more than 4 hours and should be fairly easy to trim.<<<<I seriously doubt this. Take your time and do it right. It seems like you have already made one large time suck by getting a rig that wasn't built for what you wanted and are now trying to make it the way you want.
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Old 10-08-2015, 02:29 PM   #15
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EIFS (exterior insulation and finishing system), "stucco" to most people, often uses foam boards held to a building with screws. They use plastic washers like these to spread the force so the screws don't tear through. Maybe these washers and self-drilling screws could work.

Adhesive might be better because it doesn't make holes in the metal. In a brief search online for "eps adhesive" I'm finding a 3M 78 spray and Liquid Nails LN-604 in a caulk tube. Didn't immediately find a mastic for the job.

If you can figure out who in your area distributes acrylic stucco systems like Dryvit or Senergy, you'll find foam board, tape, and adhesives there too. They might not want to sell to you directly, but at least could recommend specific product names and where to get them retail.
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Old 10-08-2015, 02:53 PM   #16
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Originally Posted by CaptainInsaneo View Post
Foam and well many things are more flexible in thinner layers. Basically you want to make plywood-esque foam for the top.
I had thought about this, but I had dismissed it because I had too many unknowns regarding adhesives. But I think you may be on to something. It would be much easier to mold thin foam around the contours of the roof. I did some more research on adhesives and I found one that is polyurethane based and should work very well.


Quote:
Originally Posted by CaptainInsaneo View Post
Quick question, how do you plan on using your skoolie? Is it going to be a non moving cabin or are you using it as an on the road RV? How long do you plan on using your skoolie for? Where do you plan on using this rig at?

You say it is only going to be driven 2 times after completion, how long are those drives going to be 50ft or 500 mi?
I am using the skoolie more like a non moving cabin. Once the renovation is complete, I will be driving in 100 miles to an RV park. I've already checked with them, and I should be good to move in next May. I expect to stay in the skoolie for 2-3 years, afterwhich I may want to drive it to a different state. But if I do move, I will likely have to redo the insulation anyways depending on the climate there. I do not plan on staying in a skoolie long term. It is more of an intermediate step to moving into a house. I'm sick of paying exorbitant rent on lousy apartments. And each year, the rent goes up while the quality goes down.
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Old 10-08-2015, 03:01 PM   #17
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Originally Posted by family wagon View Post
Adhesive might be better because it doesn't make holes in the metal. In a brief search online for "eps adhesive" I'm finding a 3M 78 spray and Liquid Nails LN-604 in a caulk tube. Didn't immediately find a mastic for the job.
Thank you for this valuable information. I was originally thinking more of a spray adhesive, but I think you are right, a construction tube type glue should work well.

Loctite 1390595 is polyurethane based, and it only cost $4.67/tube at Home Depot. I'm starting to envision a new idea. I will sketch it up and post it later today.
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Old 10-08-2015, 07:34 PM   #18
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Ok, I think my solution is taking shape. Thanks again to everyone who helped!

Above is a very rough sketch of the concept. Half of the outer frame of the bus can be seen in yellow, and it includes the long metal ribs going down the length of the bus. Inside the bus, I will take 1/4 semi-flexable foam and layer it along the sections with the sharpest curves (the green part).

I will get thicker foam (purple) and glue it to the inside of the bus. I will take the same type of foam and glue it to the outside of the bus, cutting room for the outer roof ribs. (still purple) Then I will layer 1/4 semi-flexible foam on the outer curved section (blue).

Lastly I will get 9-10 foot sections of foam (or metalic bubble wrap or something similar) and glue it over all the other foam and also glue it to the frame. (red part)

I didn't show that part really well in the drawing, so just imaging the red curve extending a few inches down the wall of the bus so that there will be good contact between the frame of the bus and the outermost layer of foam.
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Old 10-08-2015, 07:50 PM   #19
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Updated idea.



I didn't like the exterior bulge the first idea would create. I should be able to avoid it without losing any headroom or much useful space. Also, I can use less glue if I insert thicker foam next to the windows. I would reserve the thin foam (green) only for the sharp curved areas.
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Old 10-09-2015, 10:48 AM   #20
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What will be going over all this foam? Just paint?
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