Foamie build/wall frame questions!

[Jimmytg]

Hello,

It seems like I am perpetually in the planning stages of my foamie, but I want to make sure I get almost everything figured out before I start (knowing full well that there's always going to be things that come up, that I hadn't planned for!)

I'm looking at building a foamie(Standie) with the dimensions of 6 and 1/2 ft wide by 12 ft long by 6 ft tall, using PMF to cover the exterior, and 1/8" luan on the walls inside. My questions are as follows:

1. Do I need to build any sort of wood frame or can I just use 2-in foam for the build? Knowing also that if I use foam only, I will need to use wood slats for the top to help support it. Trying to keep things light.

2. If I don't build a wood frame, how would I frame the windows and the door? Do I just cut channels partway into the foam on the inside and add vertical 2x2s to support the windows?

3. I've seen people put wood studs in between the pieces of foam and attach them to the base, but I'm guessing that would show when you add the PMF correct?

4. If the recommendation is to build a frame and then add the foam making the walls 2 plus inches thick, how does one add windows when they seem to fit walls up to 1 3/4" ish inches thick.

I would love to just use foam to keep things light, but I also want to make sure that the camper is sturdy enough.

Once again, I do appreciate everyone's taking the time to read my posts, and the input and guidance you all provide! I feel like I'm getting very close to starting

Thanks!

 

[pchast]

You need less than you expect, unless you intend to add roof loading. Hard points are easily added where needed for the most part. A couple of builds use sheet metal in angle iron form as inovative supports.

 

[Pmullen503]

Hello,

It seems like I am perpetually in the planning stages of my foamie, but I want to make sure I get almost everything figured out before I start (knowing full well that there's always going to be things that come up, that I hadn't planned for!)

I'm looking at building a foamie(Standie) with the dimensions of 6 and 1/2 ft wide by 12 ft long by 6 ft tall, using PMF to cover the exterior, and 1/8" luan on the walls inside. My questions are as follows:

1. Do I need to build any sort of wood frame or can I just use 2-in foam for the build? Knowing also that if I use foam only, I will need to use wood slats for the top to help support it. Trying to keep things light.

I would inlay vertical strips of your 1/8" into the inside surface of the roof foam. Depending on the loads (Snow? Roof racks?) 12 to 24" O.C. less if curved. Make saws cuts 1.5" deep to fit your plywood and cut slats to fit. Ideally you want them flush with the inside surface so your 1/8" luan ceiling panel can be glued to the slats as well. Use a non foaming adhesive.

2. If I don't build a wood frame, how would I frame the windows and the door? Do I just cut channels partway into the foam on the inside and add vertical 2x2s to support the windows?

SInce the windows will be thinner than your walls, make those supports the width you need to accommodate your windows. You'll have a step on the inside that you'll have to cover. Do a mock up first to figure out how you want to finish them off. I'd make them flush on the outside with the wood thickness less than the flange.

3. I've seen people put wood studs in between the pieces of foam and attach them to the base, but I'm guessing that would show when you add the PMF correct?

Yes, it will show eventually due to different thermal expansion coefficients. You can hide that under the door and window flanges. It's important to wrap the wall canvas a few inches under the floor. That's what will hold the walls to the floor in the long run.

4. If the recommendation is to build a frame and then add the foam making the walls 2 plus inches thick, how does one add windows when they seem to fit walls up to 1 3/4" ish inches thick.

You won't need a frame.

I would love to just use foam to keep things light, but I also want to make sure that the camper is sturdy enough.

Once again, I do appreciate everyone's taking the time to read my posts, and the input and guidance you all provide! I feel like I'm getting very close to starting

Thanks!

 

[Jimmytg]

Thanks a bunch for the detailed responses to all of my questions! It will definitely help me with a successful build!

There is just so much involved in the planning process and that makes me hesitant to start, hoping that my plan will work out.

Thanks again!

 

[rjgimp]

Even at the size you are planning, no additional framing of wood or other material is needed. XPS foam with PMF is incredibly strong. I think you'll be surprised! I don't even think you need spars in the roof, unless you are in an area that sees heavy snow loads. Even then, I would arch the roof instead using kerf cuts or heat if you can come up with a means to apply enough heat evenly for a long enough period of time. It can be done, but it's tricky.

 

[Jimmytg]

Great info-I appreciate the guidance!

Thanks RJ!