Details on "sandwich" construction method

[Marck]

Ok I am 99.9999999% sure I understand what you folks mean by "sandwich" construction...but I was hoping someone could give me a site addy where i could SEE it being done... obne of your sites mebbe???
I KNOW you frame, put the ply on each side, with styro insulation in the gaps... just wanted to get a CLOSE look at it in progress.

[Steve Frederick]

I built the stripper, using the sandwich method, except, my outer layer is 3/4" thick. The process is simple, glue furring/studs to the outer wall, then glue closely fitted insulation in the voids, cover with your inside finish. The method allows you to finish your inside walls while still outside on a bench.
I'll be using this method to construct Mike's Lil Diner project.

Furring defines the inside profile.

Fill the voids between furring with glued insulation.

Fitt the interior covering.

Clamp the whole thing, be creative

The erected walls, ready for bulkheads and headliner.

[Marck]

Ok Thanks Steve.. i KNEW I knew what I was knowing....
Ummm ok that sounded really dumb... whaddya want, I just finished watching the presidential debate.. of course i sound dumb now.

lol

Thanks again steve.

[Larry Messaros]

You can take a look at my site as well. It is a slide in camper that I built.

http://www.puppycuts.ca/camper/camper.htm

There is also pics (some are the same, but there are a few different ones) in my photo album at:

http://www.puppycuts.ca/album/Camper/index.html

I have yet to start my trailer (it will be soon! )

Sorry the pics are not as detailed as I would like, but they were taken over 20 years ago and that's all of the pics of construction.

You can't tell by the pics but there is no exterior plywood. The inside layer is 1/8" panelling glued and nailed onto a 1x2 frame and then assembled. Then came electrical and finally insulation. I did not put any plywood on the exterior of the frame. I basically followed how most campers and trailers were being built at the time. The last thing to install was the aluminum which was standard RV type aluminum.

In all of the years that we used the camper and the back roads that we went on, we never had any problems with twisting, racking, or generally with anything falling apart.

[denverd0n]

So, on your camper you used 1/8" ply for the inside walls and aluminun on the outside. Right? Have you ever had any trouble with the 1/8" being too thin? Like, does it flex when you lean against it?

The reason I ask is because I'm trying to decide if I want to make my sandwich walls using 1/8" ply inside and out, or 1/4" ply inside and out, or maybe 1/8" on one side and 1/4" on the other side (though I haven't decided if it would make more sense to have the thicker wall inside or out).

Whatever I use for the walls it will be 3/4" thick stock for the framing. Any advice?

[mikeschn]

If you let cost be the driving factor...

I can get 1/4" luan for the outside for $9.99 a sheet.

I can also use 1/4" luan for the inside on the sidewalls.

If you are building a rounded teardrop then I need to use 1/8" luan for the headliner and the roof.

Once you leave the luan world... costs go up really quick!!!

Mike...

[Larry Messaros]

So, on your camper you used 1/8" ply for the inside walls and aluminun on the outside. Right? Have you ever had any trouble with the 1/8" being too thin? Like, does it flex when you lean against it?

I found it very flimsy as just a wall, but once all of the walls were tied together it stiffens up very nicely. There wasn't a long expanse of wall to make it flimsy.

The reason I ask is because I'm trying to decide if I want to make my sandwich walls using 1/8" ply inside and out, or 1/4" ply inside and out, or maybe 1/8" on one side and 1/4" on the other side (though I haven't decided if it would make more sense to have the thicker wall inside or out).

Whatever I use for the walls it will be 3/4" thick stock for the framing. Any advice?

Hmmm, I would probably use 1/8" on both sides for the walls. The reason being is that the side walls would not need as much support for the outside aluminum. My camper did not use any sheathing on the outside because I just followed how the commercial campers were built. The aluminum on my camper came in 12" and 16" strips and they were stapled on the tabs to the studs on the wall and the next piece would slide into a groove that would cover up the staples. The Aluminum could expand and contract without puckering. With a single sheet of aluminum you would want support underneath when it expands.

For the roof, I would probably use 1/4" but do it with 2 - 1/8" sheets to make the curve easier.

The other thing you might want to check, is for windows and doors, what kind of thickness of wall can they be installed in. The windows and door that I used were designed for a 1" wall

I agree with Mike's next message that you should stay with the luan as it is the most reasonable. The luan that I used actually had a paper covering with a picture of oak on it. It was made for finishing rooms in basements. There were also plastics strips to match that you would use to join pieces together. This made it really simple because it was instantly finished on the inside. The finish stood up very well for the 10 years that we had our camper.

Having said all that, I just came back from some of the local building stores and I may have a problem finding the same plywood. When I go down to the big city in a couple of weeks I will see what's available.

I hope this helps.

[Marck]

Ummmm ok....
I stopped at 84 lumber today to get some prices... I only stopped there because it is right behind my work....
The guy there tried to inform me that threr is no such thing as 1/8" luan. I told him I had "talked"to various people who had recently purchased it.. he told me I must be wrong... so while standing there in front of him I called Lowes, anyway, they told me they have 1/8" luan in birch, pine, maple, and a few other types. The guy at 84 lumber kept trying to tell me that they are mistaken, and must mean 1/4" and that he could give me a better deal... I politely told him no thanks and left.
I will be going to Lowes for my luan unless I find a better deal first.

[mikeschn]

My big box store right around the corner from me with the orange roof only has the 1/4" luan. To get the 1/8" stuff I have to go to Pontiac plywood. The 1/8" stuff definitely exists, but it's not as popular as the thicker stuff... so most folks will have to look a little harder for it!!!

Mike...

[Steve Frederick]

Any "real" lumber yard will stock, or will gladly order 1/8" stock. I got mine at a yard that services mostly commercial builders. They stock, 1/8" ply in birch, luan, fir, and oak. I also got 1/8" sheets of baltic birch for the galley lid from the same shop. Cost was as good as the big boxes!

[asianflava]

My big box store right around the corner from me with the orange roof only has the 1/4" luan. To get the 1/8" stuff I have to go to Pontiac plywood. The 1/8" stuff definitely exists, but it's not as popular as the thicker stuff... so most folks will have to look a little harder for it!!!

Mike...

I found the exact same thing, none of the big boxes had 1/8, they only had 1/4. But, the guy at 84 Lumber did point me to a specialty wood store and they had 1/8. They also had it in 5X5 sheets whill make life easier for me.

[john]

I can't post individual pics but I can give this address with pics of the method I chose.http://photos.yahoo.com/johngwalkerjr

john

[wired74z]

Here's an arcticle from Workbench magazine. I managed to dig my copy out last night. The paper magazine has a longer article than the online version.

http://www.workbenchmagazine.com/main/276-torsion.htm

I've been thinking of using this method to build all of the flat sections for a teardrop trailer. Just add insulation and wiring as you build the panels. I'm thinking of using pocket screws to assemble the frame before attaching the skins.

Would 1/4" skins inside and out be enough? Or should I use 1/2" on the outside? Living in Minnesota, an insulated camper is almost mandatory !

Tom

[BoilermakerFan]

Only item listed on the website now is the cutting diagram for the closet organizer.

Post more details of the construction technique and we can let you know.

[Larry Messaros]

Here's an arcticle from Workbench magazine. I managed to dig my copy out last night. The paper magazine has a longer article than the online version.

http://www.workbenchmagazine.com/main/276-torsion.htm

The url is missing the "l" in html. Here's the link:

http://www.workbenchmagazine.com/main/276-torsion.html

I've been thinking of using this method to build all of the flat sections for a teardrop trailer. Just add insulation and wiring as you build the panels. I'm thinking of using pocket screws to assemble the frame before attaching the skins.

Would 1/4" skins inside and out be enough? Or should I use 1/2" on the outside? Living in Minnesota, an insulated camper is almost mandatory !

Tom

Tom, I think that 1/4" on 2 sides would be the max that you would need. On my camper 1/8" on 1 side (inside) proved to be incredibly strong once the walls and roof were tied together. I understand that in some places it is difficult to find 1/8" luan but for strength 1/8" should be all you need.

Here's a link to some plywood that might work:

http://www.chpi.com/pages/deco.html