Using screws to hold plywood/foam construction together while gluing?

[jwiereng]

Didn’t IdaSho fiberglass glass his whole camper? Very time intensive and expensive


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Sometimes I wonder if the PMF method actually saves a lot of time. Seems like to get it nice, you still have the fill, sand, repeat and repeat and repeat again., to me it does not appear to be substantially different than fibreglass and epoxy. For me, planning a small squaredrop, I wonder how much difference the material costs would be, considering the project in is entirety, including steel frame, windows, doors, axle, tyre, hitch etc

 

[ReluctantTraveler]

Sometimes I wonder if the PMF method actually saves a lot of time. Seems like to get it nice, you still have the fill, sand, repeat and repeat and repeat again., to me it does not appear to be substantially different than fibreglass and epoxy. For me, planning a small squaredrop, I wonder how much difference the material costs would be, considering the project in is entirety, including steel frame, windows, doors, axle, tyre, hitch etc

What's the PMF method?

 

[jwiereng]

What's the PMF method?

canvas and paint - like the boat builders do. Called Poor Mans Fibreglass in the teardrop homebuilder world

 

[rruff]

Didn’t IdaSho fiberglass glass his whole camper? Very time intensive and expensive

A thin layer of FG isn't expensive at all, and doesn't take a lot of time. It makes a great hard/durable/waterproof layer for the ply.

Sometimes I wonder if the PMF method actually saves a lot of time. Seems like to get it nice, you still have the fill, sand, repeat and repeat and repeat again., to me it does not appear to be substantially different than fibreglass and epoxy.

In my experiments, PMF isn't nearly as strong (strength/weight), hard or stiff as FG/epoxy, and it creeps badly. It's much more like a heavy duty coating than a structural material.

canvas and paint - like the boat builders do. Called Poor Mans Fibreglass in the teardrop homebuilder world

Actually canvas and Titebond, instead of FG and epoxy. They get away with it on the foamie teardrops because they are small campers, and they use 2" thick XPS foam, so not a lot of strength or stiffness is needed. Certainly the materials are nicer to work with vs FG and it may be adequate depending on the application and your expectations.

 

[1000arms]

As always, Kenny, thank you for the constant advice! How "off road" do you get with your rig? I'm a bit worried about things falling apart while on jacks.

My wife is really keen on removing it from the truck if we'll be staying in one spot for a week.

I know you have a steel frame inside yours. I'd planned to build entirely with wood.

High capacity water and waste tanks (and people plus dogs) require less of a camper-frame to support them when the camper is always mounted than when the camper is designed to be unloaded and used off of the vehicle.

You could make a simpler, cheaper, and lighter camper for the flatbed you have discussed, than a camper you can use unloaded from the vehicle.

 

[1000arms]

... A few folks here recommended Boulter Plywood as a good source of quality marine-grade plywood. I know with COVID, supply and quality of everything is kind of a mess, but hopefully choosing a good supplier will make a bit of difference.

I've heard good things about Boulter Plywood.

You might find the following Wooden Boat article on marine plywood interesting:

Marine Plywood | Wooden Boat

www.woodenboat.com

 

[jwiereng]

I wonder why more homebuilds not built like IdaSHO. Simply tools, simple materials, excellent and durable results.

I also wonder why commercial RV trailers/campers are not made this way?
It is just because it takes too long, and not enough craftsman available to work in commercial production?

I’m still thinking about this, does this group have any additional ideas as to why more homebuilts are not made this way? Or why commercial models are not?

 

[IdaSHO]

Id say it is likely 90% labor related and 10% qualified builder related.

Its a LOT of labor. And it isnt difficult to build something I have, but to maintain a certain level of craftsmanship from start to finish is not easy, to say the least.

 

[ReluctantTraveler]

Id say it is likely 90% labor related and 10% qualified builder related.

Its a LOT of labor. And it isnt difficult to build something I have, but to maintain a certain level of craftsmanship from start to finish is not easy, to say the least.

Along those lines... is there any world in which its easier/simpler to use an aluminum exterior shell instead of plywood and epoxy?

I could imagine using a wooden frame and rigid foam, just like you have, but gluing aluminum panels and sealing the joints with silicone or something like that.

I could VERY MUCH be hand-waving over some serious complications, though.

 

[IdaSHO]

The serious complication would be that aluminum is both a radiant and moisture barrier. Both would likely destroy the plywood in short order. That “short order” may be 20 years, but Id argue that built like Ive done will last FAR longer than that.

 

[ReluctantTraveler]

The serious complication would be that aluminum is both a radiant and moisture barrier. Both would likely destroy the plywood in short order. That “short order” may be 20 years, but Id argue that built like Ive done will last FAR longer than that.

Ah, so I was thinking it would keep the moisture out. You're saying it would trap it against the wood and cause rot?

Does "like you've built it" include your OG epoxied version, or just the Monstaliner model? I LOVE how the liner looks, but I'm not sure I'm ready to deal with that whole process.

 

[IdaSHO]

Moisture, and not trapping it is the key. Aluminum would trap it, yes, but just as bad is that it would also likely be a surface for moisture to condense on.

While the monstaliner is one heck of a coating, you would be fine with a single stage paint for some time. I did for many years. It was nothing more than rustoleum with hardener applied with a foam roller.

Only real hangup I had with it is that even with the hardener it fades and “chalked” Monstaliner fixed both, all the while providing some added protection. Looking as good as it does was just a bonus.

 

[ReluctantTraveler]

Moisture, and not trapping it is the key. Aluminum would trap it, yes, but just as bad is that it would also likely be a surface for moisture to condense on.

While the monstaliner is one heck of a coating, you would be fine with a single stage paint for some time. I did for many years. It was nothing more than rustoleum with hardener applied with a foam roller.

Only real hangup I had with it is that even with the hardener it fades and “chalked” Monstaliner fixed both, all the while providing some added protection. Looking as good as it does was just a bonus.

From watching a bunch of application videos, it looks like a real pain to put on, but... perhaps no more so than epoxy and paint?

 

[Alloy]

I’m still thinking about this, does this group have any additional ideas as to why more homebuilts are not made this way? Or why commercial models are not?

It takes time

 

[Alloy]

Along those lines... is there any world in which its easier/simpler to use an aluminum exterior shell instead of plywood and epoxy?

I could imagine using a wooden frame and rigid foam, just like you have, but gluing aluminum panels and sealing the joints with silicone or something like that.

I could VERY MUCH be hand-waving over some serious complications, though.

Aluminum needs a continuous bond or it will warp/buckle.

Edit: unless it was 1/8" or 5/32" and you planned out the welding so it was near corners/bends.....then you'd forget the outside plywood and spray foam the inside then you'd have an air sealed wall