Materials selection

[motas]

Hey all. I've seen a lot of discussion regarding different materials for construction and need to decide on my own. So I thought it would be helpful to make a thread with the pros and cons of each and some additional information and pictures. I will try to keep this post up to date with additional information from replies and research but for now it will be pretty basic.
Steel frame and steel panels
Advantages
Low cost
Fairly simple construction
High strength
Fairly easy repair
Disadvantages
Heavy
Corrosion
Poor insulation

Steel frame aluminium panels
Advantages
Fairly simple construction
Fairly low cost
Fairly easy repair
Disadvantages
Still heavy
Corrosion between aluminium and steel
Poor insulation

Composite panels
Advantages
Lightweight
Good insulation
Easy construction
No corrosion
Disadvantages
Expensive
Hard to repair

Aluminium frame aluminium panels
Advantages
Fairly light weight
Fairly easy repair
Little corrosion
Poor insulation
Disadvantages
Harder to build

Fiberglass
Advantages
Light weight
Easy to repair
Low cost
No corrosion
Disadvantages
Hard to build
Poor insulation

Timber frame plywood panels
Advantages
Very low cost
Lightweight
Very easy to build
Easy to repair
Disadvantages
Rot
Relatively weak

If anyone has more material choices, pros, cons, pictures or any other information I'd really appreciate it and will add it to this post. I'll also continue to update it with my research.
Thanks.

 

[LukeH]

How is slapping some resin on a bit of fibreglass matting over a composite panel difficult?
You're in the middle of nowhere and you've managed to catch a branch that would have gone through any of your material choices.
Steel? Tape it up temporarily because there's no way you're travelling with spare panels. Your magic sticky tape is good, but not as good as the original panel, you have to be careful not to rub it. Over a few weeks the UV will weaken the material and the glue and there's a chance it'll start leaking.
Alu? Idem.
GFRP? Well you just happen to have a roll of mat and a pot of resin. In the spares bin.
Sand a bit around, slosh on some resin, put some mat on, resin it and let it dry.
Good as the original because it IS the original material. The rest is down to how good you are at sanding. But it'll remain waterproof because it's fully compatible.
How is that harder than replacing a metal panel?
What's more if you bonded the metal panel onto the frame with Sika or uhb tape you will really suffer when the time comes to replace it back home.
But hey, maybe welding a patch onto a metal panel won't set fire to the interior insulation...
A roll of GF mat is like carrying a spare panel, only rolled up and more versatile

 

[motas]

Hence why I listed fiberglass as easy to repair. Composite panels are not easy to repair because the panel has to be replaced which is generally attached to other panels with epoxy. I am sure you can patch it with fiberglass (as I'm sure you can with almost any panel) however this is not a proper repair as it is most certainly not the original material. Steel or aluminium riveted to the frame can quite easily be replaced in most small towns and is as good as new. However you are correct it is not feasible to carry a spare panel in isolated areas so it is harder to repair than fiberglass.
I have revised the relevant materials to fairly easy to repair and fiberglass left as easy to repair to reflect this as you do make a good point, however I have left composite panels as hard to repair because unless I am mistaken it is very difficult to fully repair damage.

 

[getout]

What about wood (for frame and/or exterior)? Would you mind adding that with your categories and thoughts?

Sent from my SCH-S720C using Tapatalk 2

 

[Bernard_Roofus]

I hate to get on the band wagon, but I work in the aviation industry and I agree, composite structures are far more difficult to correctly repair. You would need a vacuum pump, expensive resin, and time. Also if the panel's integrity was damaged, then it is a whole other repair method to bring it back to "origional strength". Not to mention depending on the type of composite, the dust from sanding is very dangerous to breath. So you would have to include a filtered respirator in your repair kit. I am not saying composites are bad, I love em, they just have their own unique properties. Not all resins are compatible and mixing them may require a scale vs a measuring cup and temperature is a huge factor in repairs. For example, if you have a FRP (fiberglass reinforced panel) that is damaged, you would not just lay some glass mat over it and resin to fix it. That would cover the damage, but it does not repair the integrity, you would have to cut the damged area out and splice in a new section. Sorry to ramble, but I work with composites like kevlar, carbon fiber, fiberglass and honeycomb structures for a living.

 

[westyss]

I guess I should respond to this too seeing you have included an image from my build, composite panels are not what I would call expensive when you crunch the numbers, more like they are hard to get. Maybe someone can comment on the cost of the WHOLE wall structure on certain types of construction, ie. outside material, insulation, inside material and whatever is supporting the structure. With what I used the panels are a whole unit, no structure, insulation, finished inside material needed. Cost of my panels was $8600 and around $1500 for the aluminum corners so a total of around $10,000, took me a very short time to put it together so factor in the time it takes to manufacture any other type of system even though you are not paying yourself for the work but factor it in anyway, because it does take a considerable amount of time to "do it yourself". I would imagine it would start to add up and perhaps exceed the cost of a composite structure.
Like I said the cons for composite should be AVAILABILITY not cost.

Repairs: I cant see why a composite panel would be a difficult repair, am I missing something? Slap some mat and resin and its good to go.......... or use some 291 to patch it up if its a small ding, looking at my camper would you say that it smashed into a fire hydrant and made a big gash in the side by the cassette access door? Cassette door was totally destroyed and I had to purchase a new one but the panel was repaired simply by troweling on some grey Sika 291, its the exact color match. look closely.

Something that has always stuck with me too was a comment someone made to me and I think I read it somewhere and it was meant as a statement about building boats and not campers but I feel it is very similar, and that is " the time and cost of building the shell ( Hull of a boat or shell of a camper) will be around 30%. 30% seems to be a pretty accurate number so in reality the time to build the shell should be recognized as a small time and cost componant of the entire build and that includes R&D.

One last thing, I call it composite only because it is comprised of several materials all glued together, maybe it can be called something else, but it isnt like an airplane structure with high tech materials supplying great flexibility and light weight strength, more like a rigidly made box.

 

[motas]

What about wood (for frame and/or exterior)? Would you mind adding that with your categories and thoughts?

Sent from my SCH-S720C using Tapatalk 2

I did remember this afterwards and I will add it to the list later.

I hate to get on the band wagon, but I work in the aviation industry and I agree, composite structures are far more difficult to correctly repair. You would need a vacuum pump, expensive resin, and time. Also if the panel's integrity was damaged, then it is a whole other repair method to bring it back to "origional strength". Not to mention depending on the type of composite, the dust from sanding is very dangerous to breath. So you would have to include a filtered respirator in your repair kit. I am not saying composites are bad, I love em, they just have their own unique properties. Not all resins are compatible and mixing them may require a scale vs a measuring cup and temperature is a huge factor in repairs. For example, if you have a FRP (fiberglass reinforced panel) that is damaged, you would not just lay some glass mat over it and resin to fix it. That would cover the damage, but it does not repair the integrity, you would have to cut the damged area out and splice in a new section. Sorry to ramble, but I work with composites like kevlar, carbon fiber, fiberglass and honeycomb structures for a living.

In this list I was not referring to patches as you can patch any material with the right material fairly easily, but that is not a full repair. I would much rather repair a steel frame or panels than a sandwich composite panel. It is quite simple to repair steel. Fiberglass is the only exception since it can be repaired easily with its original material.

I guess I should respond to this too seeing you have included an image from my build, composite panels are not what I would call expensive when you crunch the numbers, more like they are hard to get. Maybe someone can comment on the cost of the WHOLE wall structure on certain types of construction, ie. outside material, insulation, inside material and whatever is supporting the structure. With what I used the panels are a whole unit, no structure, insulation, finished inside material needed. Cost of my panels was $8600 and around $1500 for the aluminum corners so a total of around $10,000, took me a very short time to put it together so factor in the time it takes to manufacture any other type of system even though you are not paying yourself for the work but factor it in anyway, because it does take a considerable amount of time to "do it yourself". I would imagine it would start to add up and perhaps exceed the cost of a composite structure.
Like I said the cons for composite should be AVAILABILITY not cost.

Repairs: I cant see why a composite panel would be a difficult repair, am I missing something? Slap some mat and resin and its good to go.......... or use some 291 to patch it up if its a small ding, looking at my camper would you say that it smashed into a fire hydrant and made a big gash in the side by the cassette access door? Cassette door was totally destroyed and I had to purchase a new one but the panel was repaired simply by troweling on some grey Sika 291, its the exact color match. look closely.

Something that has always stuck with me too was a comment someone made to me and I think I read it somewhere and it was meant as a statement about building boats and not campers but I feel it is very similar, and that is " the time and cost of building the shell ( Hull of a boat or shell of a camper) will be around 30%. 30% seems to be a pretty accurate number so in reality the time to build the shell should be recognized as a small time and cost componant of the entire build and that includes R&D.

One last thing, I call it composite only because it is comprised of several materials all glued together, maybe it can be called something else, but it isnt like an airplane structure with high tech materials supplying great flexibility and light weight strength, more like a rigidly made box.

For the purposes of this I have split construction time and money. Your time may be worth a lot to you but for someone like me who works part time money is more of a concern than time. I have revised steel structures to fairly simple to build and left composites as easy to build to reflect this. Again you mention that it is easy to patch which is completely true it is very easy to patch, but not so simple to fully repair. I will add in the ease of emergency repair to each one soon to make them more accurate. Also I hope you dont mind the use of your picture if you do I will take it down, your camper is a great build though and a good example of composite panels.
Thanks.

 

[shachagra]

What about wood (for frame and/or exterior)? Would you mind adding that with your categories and thoughts?

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I think wood/epoxy is a great material selection. I think it depends mainly on what you are comfortable working with. Wood is very light and strong and when coated with epoxy and glass even stronger and decay resistant. It is very easy to repair. The only major repair we made to our rig in 16 months of living in her was completed by my 16 year old boy on a beach in Sicily. I never had to go back and redo it as I planned. It is the predominant material in custom boatbuilding.

 

[getout]

I think wood/epoxy is a great material selection.

Ironically enough, your build(s) were exactly what I was thinking of when I asked the question. Thanks for you comments.

 

[Bernard_Roofus]

Wood is also very easy to work with, and cheap.

 

[motas]

Have added wood frame and plywood panels as that is the way I have seen out of wood. Recently my girlfriend found a big pile of coolroom panels for sale on Facebook for $150 so I have bought them and plan to build my camper out of them. Not as good as some other options but for that price its worth a shot. Will let everyone know how it goes.

 

[Billhilly]

I think wood/epoxy is a great material selection. I think it depends mainly on what you are comfortable working with. Wood is very light and strong and when coated with epoxy and glass even stronger and decay resistant. It is very easy to repair. The only major repair we made to our rig in 16 months of living in her was completed by my 16 year old boy on a beach in Sicily. I never had to go back and redo it as I planned. It is the predominant material in custom boatbuilding.

Would you be able to give us a short description on how you insulated your truck, and any improvements you can now see? Wood is one thing I hadn't really considered, yet! I had wondered about spray polyurethane instead of polystyrene. And how did you then line the inside?

 

[Darwin]

It's too bad NA RV manufactures don't use the wood/epoxy/glass building techniques like shachagra mentioned. I wonder if it's cost prohibitive?

 

[shachagra]

There is lots in this thread, but couldn't find anything on the insulation

http://www.expeditionportal.com/for...Turkey-International-7500?highlight=shachagra

Basically the cabin was built just like a house, but with strips of 2"X3/4" marine plywood where you would have studs, polystyrene foam where you would have roll insulation, and 1/4" marine plywood instead of stucco and drywall. The "studs" are epoxied to the outer and inner plywood sheathing. They plywood was very high quality, I still pull small pieces off the scrap pile that are weathered but perfect after sitting outside for 4 years.

I thought it would be easier to build the sides, top etc in the garage like a SIP (structural insulated panel) and then erect onto the truck when finished, but now after doing a small van that way am confident that the way I built it (like a house) was probably easiest.

 

[Billhilly]

There is lots in this thread, but couldn't find anything on the insulation

http://www.expeditionportal.com/for...Turkey-International-7500?highlight=shachagra

Basically the cabin was built just like a house, but with strips of 2"X3/4" marine plywood where you would have studs, polystyrene foam where you would have roll insulation, and 1/4" marine plywood instead of stucco and drywall. The "studs" are epoxied to the outer and inner plywood sheathing. They plywood was very high quality, I still pull small pieces off the scrap pile that are weathered but perfect after sitting outside for 4 years.

I thought it would be easier to build the sides, top etc in the garage like a SIP (structural insulated panel) and then erect onto the truck when finished, but now after doing a small van that way am confident that the way I built it (like a house) was probably easiest.

Thanks for that! So when you look at the SketchUp views below, do you see wood and fiberglass, or perhaps an alloy exterior like in post #1? Or?
I realise we all bring a different 'skill set' to the table, but as much as I like the composite panel deal, cost is clearly a factor going that route. I have zero glassing experience, but can see the massive benifits of building a monocoque structure. I can also see advantages with alloy for seal faces, hinge attachment etc, but maybe I underestimate this wood stuff!

I guess spray on polyurethane would be a insulation option if you build yourself a trimmer deal like they use on your island. Cheaper, better insulation values, and waaaaay messier!