Lifting roof XPStream - making improvements

[OP827]

Greetings from Alberta. I am deciding on my TTT floor plan design, frame and plywood floor are ready to start interior and walls. This is my first post for the build. It is a foamie with fibreglass and thin plywood reinforcement. I do have some diy experience with fibreglass, aluminum, fabrics, wood, some welding. I have drafted the floor plan for your advice please. Any input is highly appreciated. I know this plan has its inconveniences when the queen bed is expanded, but I feel it is providing good sleeping space that way as well. There is also an opportunity to make upper side of left side bathroom wall to overlap the queen bed for more space inside the bathroom(for wash sink maybe). The trailer exterior and interior walls will be foldable down from kitchen countertop level. The Conceptual mockup is in my album at this site.

Thanks in advance for all your constructive input here.
Oleg

24-NOV-2019 EDIT: Since this initial concept model below the trailer design has changed substantially towards aerodynamically streamlined shape with lifting roof and folding side walls.

 

[KCStudly]

It looks good to me. I'm not sure I understand what you are saying about the folding walls. Will it be a drop down/pop up hard roof?

 

[OP827]

It looks good to me. I'm not sure I understand what you are saying about the folding walls. Will it be a drop down/pop up hard roof?

Thanks KC and NO or "sort of", the trailer fold down design will be similar to Gobur or Esterel caravans out of UK. It will have fold down wall and roof will sit on top of them. Similar to pictures in this post http://www.caravaning.in.ua/forum/viewtopic.php?f=51&t=2501 or google Esterel caravan images, but it will be with bathroom and made of 1-1/2" XPS foam fibreglass sandwich.

 

[KCStudly]

Ah, a hard sided pop up. Those were the words that were escaping me in my prior post. Cool.

 

[OP827]

Finaly after lots of thinking about the concept, the floor plan and how the trailer will fold (it is going to be really cool if the folding design idea works), I had some sawdust flying and made some small progress with finishing frame and almost finished gluing together the floor, last piece is left to attach. Soon will be using the floor as a build table to laminate all wall panels. I am looking forward doing something every day to make progress. Wish me luck.

 

[OP827]

Next is to the trailer walls sandwich construction.

I am going with 1/8" Baltic birch from interior glued to 1-1/2" XPS Foamular 300 rigid foam (bent/curfed or straight) and laminated with 2 layers 6oz fiberglass cloth and epoxy from exterior and then coated with polyurethane paint for UV protection and apperance.

There will be reinforcement in corners and joints with wood, epoxy filler, and FG tape. On the exterior surface I will also grove and glue thin strips of wood every so often (4" and more) to eliminate potential for delamination and reinforce the FG surface, especially where skin will see compression forces.

Any comments on the above?

 

[KCStudly]

You will want to figure out were you want anything to screw to the walls (fenders, cabinets, shelves, light switch plates, light fixtures, coat hooks, etc.) and decide how you will reinforce these areas to accept screws.

Alternate methods for attaching shelves include dadoes into the foam, but with such thin inner skins and (I am assuming) wooden cabinets (in lieu of foam) that can create some assembly hurdles, IMO.

 

[OP827]

You will want to figure out were you want anything to screw to the walls (fenders, cabinets, shelves, light switch plates, light fixtures, coat hooks, etc.) and decide how you will reinforce these areas to accept screws.

Alternate methods for attaching shelves include dadoes into the foam, but with such thin inner skins and (I am assuming) wooden cabinets (in lieu of foam) that can create some assembly hurdles, IMO.

Thanks for your input KC and yes there will be reinforcements. The furniture and internal framing will be self-supporting and work together with the wall structures. The approach is like monocoque in boat or airplane structures where every element is not only just a furniture, but also can carry part of the load to keep the trailer structure together and various joining techniques will be used to achieve that.
I was just mostly asking about the skin sandwich itself, especially outside: will 2 layers of 6oz fiberglass on top of ridig foam work well or more maybe needed (moreweight )? I hope 2 layers will work well.

 

[KCStudly]

I did a single layer of 6 oz over the outside of my ceiling skin on my front radius. Not the same as foam, but all indications are that it would be fine over foam. Two layers might even be overkill.

Maybe Mel/Atahoekid will weigh in with his experience. He did an extra wide hybrid foamie (Road Foamie build thread link) with wood interior skins and epoxy/glass exterior.

 

[OP827]

KC, what is your trailer outside ceiling skin made of, or you meant your plywood ceiling interior, just outside of it that will face foam, never mind then, I got it.
I sent PM to Mel, cause I could not easily find in his build thread how many fiberglass layers were laminated on his Road Foamie, but did not hear back from him yet. Foam is much less of compresion strength as plywood.

 

[KCStudly]

Foam is much less of (compression) strength as plywood.

Yes, but having worked with both to a certain degree, it was very impressive how much the plywood firmed up with just a single layer of glass, even after having been formed around a 13-1/2 inch radius (tho I must admit that I do not have a lot of experience with glass).

I think you have it, but just to clarify, I am building inside out with 5 mm ply, 1-1/2 inch thick foam (on the roof it will be two layers of 3/4 thk), TB2, canvas, and paint. To reinforce the outer fibers of the ceiling skin where it formed around the relatively tight front radius, I added a layer of 6 oz glass cloth and epoxy which will be covered by the foam (which is about the stage that I am at now).

From GPW's reports, the canvas over foam can be dented relatively easily (but tends to come back with heat). I'm a little embarrassed to admit that I have committed so far in my build and still have not done a test sample to prove its durability to myself, but figure that if I am not pleased with the result when I do, I can always use epoxy under and over the canvas instead of just gluing it down.

My thoughts are that a single layer of 6 oz and epoxy would be much more durable than canvas and glue, but still might take some damage that two layers would repel.

I guess it comes down to what you want, how "bullet proof" you want it to be, how much time and money you want to spend, and what kind of conditions you plan on pulling your trailer through.

I ramble. Just sort of spewing out some thoughts on the subject. Hope it gives you something useful to ponder.

 

[OP827]

You are right KC. When the time comes, I'll do one layer first and see how it feels and then I can sand and add one more layer or paint. Now I need to start cutting and gluing some foam, wood and plywood for walls and cabinets. Just finished gluing last piece of 5/8" plywood for the floor in front, waiting for epoxy to cure .. it is cold in my garage, running some heater to make the cure happen, tried Ecopoxy for the first time, used West system before.

 

[KCStudly]

We have a saying around here, "no pics, didn't happen". We need to see the pics!

 

[Shar-TNT]

Hey there, OP827! I am a fellow Albertan who built my first foamie in May/June 2014. I will be interested to see your progress and you have my sympathy as you build despite our wonderful weather here in Alberta.

 

[OP827]

We have a saying around here, "no pics, didn't happen". We need to see the pics!

LOL to you too KC, there it is with my "clamping MDF with screws contraption" and routered tongue and grove in plywood:

Sheryl, thanks for your kind words, appreciate that. I additionally insulated the garage door with 3/4 EPS foam so it is a little warmer there

 

[OP827]

And this is how my plywood but joints look like, this one is not perfect, a little glue void there, but it is still holding very strong. I did 1/4" groves both ends and inserted 1/4" baltic birch strip, all buttered with cab-o-sil thickened epoxy.

 

[KCStudly]

That will do nicely.

 

[OP827]

I think I will be able to do epoxy during winter, it worked for this small joint. It was -5oC outside and my garage needed a heater to be in epoxy temperature range. Using a 10 inch strip cut from 6mil vapor barrier, MDF strip, 30 drywal screws, 5 oz epoxy, a cup of cabosil produced a nice clean and strong joint. I had a small air heater blower under the plywood set to a mild temperature overnight and it is snowing this morning. Plywood absorbs epoxy around the glue-up and becomes a composite. Nice looking mirror like surface of the joint, very little sanding will be needed. I'll coat the complete plywood floor with epoxy eventually when I am done with all wall and furniture panels. It will all come together, one day.. It is a jorney for me, not a race. I want to do it on my own (usually slow) pace, and do it right..... I know I am dreaming.. nothing is perfect.

 

[OP827]

Obviously I got side tracked for the last two days. While indeciding about bending plywood and foam sandwich and how to best do it, I decided to build outfit saw horses of specific height that will match my table saw and will be also foldable, it is getting tight with space. Cost in materials to built them was 0.00$ as all needed materials were re-used and repurposed whatever old stuff I had in my garage and backyard, some old demolished deck 2x6s, some small pieces of plywood, 1/2" dowels, hd hinges, aircraft cable and screws. Came up with the design based on what I browsed on web, but it is not a copy of anyones design, just similar ideas combined into something usable. They are very sturdy and still not heavy, much better than anything thin metal or plastic stuff we buy in big box stores. It was nice to hand plane old deck spruce board to its original texture and get the warp out at the same time. When I put some plywood or OSB on them, the height matches my table saw table nicely, so I can now handle big sheets or long board with comfort and safety.

 

[OP827]

Back after a long break, spent many hours thinking of design and then continued to building walls. Since i have no big table and space is limited in two car garage, had to use the trailer plywood floor as gluing and clamping surface. it worked well. most of the lower part not folding walls are glued up, kitchen cabinet face frame and some cabinet walls are cut and ready for glueup. Pictures are below. Home made dust collection system had to be built too. my project needs a name.. shape is streamlined when in transport position based on discussions on this forum. small model mockup picture is in my album.

Anyone knows how to change the name of the whole build thread with a new name?