Weight savings with a Foamie build vs plywood?

[BrianInVA]

Quick question - I’ve been searching and I’m finding it nearly impossible to locate a “frugal” (read cheap) source of xps foam. However, I’m finding cheap sources of plywood and various sizes of lumber all over Facebook Marketplace.

How much weight is saved with a Foamie camper build vs a plywood/wood small camper build? I hope to build a 6”x10’ vargo type “standy” camper similar to the image below. My tow vehicle weight limit is 1500lbs.

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[GPW]

Consider plywood averages 57 lbs. per cubic foot , Foam is a LOT less ....

Regarding cost , a sheet of foam is still less than a sheet of 3/4" plywood ...around here ...

[Pmullen503]

Don't compromise to save a few hundred today. You won't miss the extra money spent a few years from now. You will regret having spent months working on a trailer that's heavier than it should have been because you wanted to save a few bucks.

[ghcoe]

A 4'x8'x2" piece of Corning XPS Formular 250 weighs 7.5lbs. As stated above a piece of OSB or Plywood in the 1/2" range is around 57lbs. Building a simple 4'x8' square drop body like I do would require 1 sheet of OSB 7/16" and 4 sheets of XPS 2". This would weigh 87lbs before canvasing and adding doors and windows. Now building the same body with just plywood or OSB would bring the weight to about 285lbs before canvasing and adding doors and windows. As you can see building with XPS is nearly 200lbs. lighter. Of course the bigger the build the more difference will be noticed.

My complete 4'x8' builds on a harbor freight trailer usually come in around 375lbs. The Harbor Freight trailer weighs 253lbs. Door, window and canvas/paint only adds about 35lbs.

Building with XPS also gives you the extra benefit of adding insulation into the build without adding even more weight or doing without insulation at all. Also, you don't have to worry about wood rotting.

[tony.latham]

My tow vehicle weight limit is 1500lbs.

If you build something similar to the camper in the photo using traditional methods, it will more than likely weigh well over your 1500 pound max.

And by the way, because of the frontal mass of that design, it'll have a lot of drag. In other words, for a small car, it'll be a beast to tow at anything above 50.

I don't mean to be the bearer of bad news.



Tony

[BrianInVA]

My tow vehicle weight limit is 1500lbs.

If you build something similar to the camper in the photo using traditional methods, it will more than likely weigh well over your 1500 pound max.

And by the way, because of the frontal mass of that design, it'll have a lot of drag. In other words, for a small car, it'll be a beast to tow at anything above 50.

I don't mean to be the bearer of bad news.



Tony

My tow car is a 2009 Ford Crown Vic, a big old police interceptor sedan with a small v8. The towing capacity is limited to 1500lbs, but only due to its type of rear suspension. Ford trucks with the same motor and transmission had much higher towing capacity.

[twisted lines]

I want to go to HD, and try a Foam board like the shape of the Roof

[Pmullen503]

.........And by the way, because of the frontal mass of that design, it'll have a lot of drag. In other words, for a small car, it'll be a beast to tow at anything above 50.

I don't mean to be the bearer of bad news.



Tony

That's going to be like towing a parachute....

A vardo has the advantage of standing room, taller doors, etc. which makes it easier to reconfigure the inside for sleeping, eating, sitting and cooking. So, if you don't plan to move it very far or very often, the design has definite advantages.

[dbhosttexas]

A LOT is going to depend on the specific species of wood the plywood is made from and how dry it is, but on average a 4x8 sheet of 3/4" plywood will weigh about 60lbs.

A 4x8 sheet of 1" XPS foam board insulation weighs 4.41 lbs. It would take close to 12 sheets of foam board to equal the weight of one sheet of plywood.

Plus your plywood will have zero insulation value

[BrianInVA]

.........And by the way, because of the frontal mass of that design, it'll have a lot of drag. In other words, for a small car, it'll be a beast to tow at anything above 50.

I don't mean to be the bearer of bad news.



Tony

That's going to be like towing a parachute....

A vardo has the advantage of standing room, taller doors, etc. which makes it easier to reconfigure the inside for sleeping, eating, sitting and cooking. So, if you don't plan to move it very far or very often, the design has definite advantages.

I’m going to make the front end similar to the FoamStream here on the forum, for better aerodynamics. Think that will help?

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I just found a tutorial on making cone shapes with foam so the process to cut and glue the top semicircle at the top of the front end to meet the roof line looks fairly straightforward.
https://youtu.be/QKPtQksKBxM

[GPW]

The FoamStream does tow very easily … like nothing is there … My old square Jayco towed like a Barge in molasses … ugh !!! Shape is everything …

[CRZ42]

The extra money spent on foam is well worth the weight savings and lack of rot. Keep keeping an eye on FB marketplace and craigslist and something will popup sooner or later.
Another possible source if you haven't already checked is building supply houses. The local one near me was $7 less a sheet but you had to buy 10 sheets minimum, at the tie I found this out, I only needed one sheet. But when I start my next build I will be going there.
Another option is talk to any contractors that you might have in your network. They may have leftover/partial sheets they can give you. I managed to get some chunks (under half sheets) that I could use for shelves or braces.

[tony.latham]

is well worth the weight savings and lack of rot.

Folks keep bringing up rot with wooden teardrops. It's malarky. A properly built wooden teardrop is no different than a properly built wooden house. They don't rot.

Now... if you make the mistake of using OSB in the floor, and it gets wet, it's oftentimes called rot. And it's not. It's wet OSB.



Tony

[twisted lines]

I just found a tutorial on making cone shapes with foam so the process to cut and glue the top semicircle at the top of the front end to meet the roof line looks fairly straightforward.

You May find a search for (Orange peel pipe cap) Handy for a shape like that.

[BrianInVA]

Keep keeping an eye on FB marketplace and craigslist and something will popup sooner or later.
Another possible source if you haven't already checked is building supply houses. The local one near me was $7 less a sheet but you had to buy 10 sheets minimum, at the tie I found this out, I only needed one sheet. But when I start my next build I will be going there.
Another option is talk to any contractors that you might have in your network. They may have leftover/partial sheets they can give you. I managed to get some chunks (under half sheets) that I could use for shelves or braces.

After a LOT of FB Marketplace searching, I found a bunch of unused 3" Foamular 250. A contractor accidentally ordered two times what he needed for a refrigerated warehouse, and was selling it for $40 a sheet. Two inch xps is $39 a sheet locally. So I picked up a dozen sheets. I'll lose two inches of interior space each way, but this stuff is R15 and quite strong/rigid.