Rigid foam cabinets?

[Patricia D.]

This video on constructing very lightweight cabinets from rigid foam insulation appeared on youtube today. Aesthetics aside, could this be a good idea for a trailer rebuild? Would they withstand the movement of a trailer on the road?

https://www.youtube.com/watch?v=ucf2FVIdr1Q

[Donna D.]

Travel trailers are like earthquakes going down the road. I wonder if this stuff would turn to powder after a while?

[Mike Magee]

They claim that people have built ultra light aircraft (wings and all) out of this stuff!

[Raz]

Very clever.

[LyleB]

The guy explained that it is used for aircraft, including the wings, seems that would be way more critical and stress invoking than interior cabinetry.

I will definitely be trying this eventually.

I've been following Jed (the guy who made the video) on his YouTube channel for quite some time, including a couple of van builds that he has done. He seems to have a pretty good handle on what works and what doesn't, so if he's sold on trying it out...

[LyleB]

A second thought on this, since I'm planning to replace the carpeting in my Scamp. If this does not compress, would placing a layer of this on the floor prior to Allure work?

Hmmmmm.

Would replace and probably improve the insulating performance of the carpet.

Have to think about that for a while.

[tractors1]

Originally Posted by Donna D.

Travel trailers are like earthquakes going down the road. I wonder if this stuff would turn to powder after a while?

Probably not. I work with EPS foams for making router templates; it's not like styrofoam at all. Styrofoam does fall apart as a trailer insulation (it was widely used in 70s-80s stick built trailers.)
EPS is a much firmer consistency due to the very fine bubbles produced as the product is made.

I also use it as the divider material for drawers I make as it's quite light and easily cut to size on a table saw; the outer layer has a smooth skinned feeling to it.

[Jim Thor]

Very good idea

[steve dunham]

Originally Posted by tractors1

Probably not. I work with EPS foams for making router templates; it's not like styrofoam at all. Styrofoam does fall apart as a trailer insulation (it was widely used in 70s-80s stick built trailers.)
EPS is a much firmer consistency due to the very fine bubbles produced as the product is made.

I also use it as the divider material for drawers I make as it's quite light and easily cut to size on a table saw; the outer layer has a smooth skinned feeling to it.

Are we talking about styrofoam insulation by Dow ,which is used as building insulation in walls ,under concrete slabs , under roofing or as foundation insulation or the white foam used in crafts , coffee cups and plates . It's kind of like kleenex , kleenex is a tissue, but not all tissues are kleenex. I have worked on remodel projects where genuine Dow styrofoam was used as insulation back in the 70's and it was still in great shape 40 years later.

[Dudley]

I fly rc planes and we make planes out of depron foam. If you want strength then add a layer of 3/4 ounce fiberglass cloth and use water based polyurathane or thinned epoxy to bond it. If you go to the websiteTeardrops n Tiny Travel Trailers • Index page you will find a section called foamies with them building whole tear drops out of the stuff.

[samclem]

To clear up some points:
- The foam they are using here is "XPS" for "eXtruded PolyStyrene." It is not "EPS" which is "Expanded PolyStyrene." Both types of foam are sold in home improvement stores. The XPS is stronger and has a smooth finish, the EPS is weaker and is made of bunches of beads that are squeezed together. Just to confuse things, "Styrofoam" coffee cups and cheap coolers are >not< Styrofoam, they are EPS (you can see the little beads in them). Styrofoam is a Dow trademark for their XPS foam (it is blue, and often stocked in HD or Lowe's stores near the similar pink XPS from Owens-Corning). EPS sheets are almost always white.
- While it is true that some airplanes are fabricated using foam, that foam is almost always surrounded by very well engineered and tough fiberglass cloth or carbon fiber cloth in an epoxy matrix. The idea may be similar to the way they are making the cabinets in the OP (the foam provides almost no tensile or compressive strength, it is just there to keep the skins apart. The skins do the work), but nobody is building airplanes using from foam, primer/paint, and screening material.
- Foam covered with fiberglass and epoxy is not hard to do at home and makes very good structures. I don't know how well cabinets made using the techniques shown in the video would hold up to real-world use, and if you want them to look good it would take a LOT of finishing/filling to get there. Also, with this type of construction, any place where a "point load" will be (hinges, the place where the cabinet is hung on the wall or attached to the floor, places where shelves will be, etc) needs to be reinforced. That is usually done by removing the core material (the foam) in that place and providing something beefier (some wood, or epoxy with fillers in it) for a fastener to grab on to, and which can spread the load over more skin area. It's not hard to do, but it is best done during the initial design.
- Over at the "Teardrops and Tiny Trailers" site there are a lot of folks who build their own lightweight trailers using foam and fiberglass, as well as cheaper methods using foam covered with cotton cloth and this same "Gripper" primer shown in the video. Others substitute "Tightbond" glue for the primer. Where wood is used (floors, etc) they generally heavily drench it in thinned polyurethane to stop it from absorbing water. It seems to make some pretty good trailers that hold up to the weather (especially if covered with some good paint). But, if there's no "hard" exterior shell formed with something sturdy (e.g. fiberglass cloth in epoxy), then bumps from any object can leave a dent in the foam. Maybe not so good for lower cabinets in a trailer that get banged around a bit.

[Gina D.]

Those are basically miniature SIPs panels. Its an intersting way to build entire walls without framing and they have been used in the Tiny House industry for awhile now.

The advantage is weight and ease of construction..the disadvantage..cost.

Note the size of the tiny house in these pics on a single axle trailer. You could get so much more bang for your buck.

Also note the Boler in the background of one of these pics

Tiny House Reinforced Structural Insulated Panels at Lowe's Home Improvement - Non-warping patented honeycomb panels and door cores

[k corbin]

It's fine but you actually don't need to put any foam in it. You can do a stress skin cabinet panel without the foam layer using just the wood strips and the 1/8" plywood skin. The foam is not doing all that much in the way of structural support in this application.

The cabinetry in boats and aircraft often use honeycomb materials as the inside layer.

[Raz]

Originally Posted by k corbin

It's fine but you actually don't need to put any foam in it. You can do a stress skin cabinet panel without the foam layer using just the wood strips and the 1/8" plywood skin. The foam is not doing all that much in the way of structural support in this application.

The cabinetry in boats and aircraft often use honeycomb materials as the inside layer.

I'm not sure what you are referring to? In the video they used foam board stiffened with fiberglass screen. No plywood involved. Without the foam all you have is the screening.

[floyd]

I once went to an aircraft junkyard with the hopes of buying a fuselage for a boattailed speedster project car. There was no light plane of the right size to make a car body which had enough structural integrity to stand the rigors of road use. There may be some out there but from what I've seen its a different engineering endeavor altogether.
Some days on concrete highways, a small fiberglass trailer can look like a basketball is chasing you.

[tractors1]

Originally Posted by samclem

To clear up some points:
- The foam they are using here is "XPS" for "eXtruded PolyStyrene." It is not "EPS" which is "Expanded PolyStyrene." Both types of foam are sold in home improvement stores. The XPS is stronger and has a smooth finish, the EPS is weaker and is made of bunches of beads that are squeezed together. Just to confuse things, "Styrofoam" coffee cups and cheap coolers are >not< Styrofoam, they are EPS (you can see the little beads in them). Styrofoam is a Dow trademark for their XPS foam (it is blue, and often stocked in HD or Lowe's stores near the similar pink XPS from Owens-Corning). EPS sheets are almost always white.
- While it is true that some airplanes are fabricated using foam, that foam is almost always surrounded by very well engineered and tough fiberglass cloth or carbon fiber cloth in an epoxy matrix. The idea may be similar to the way they are making the cabinets in the OP (the foam provides almost no tensile or compressive strength, it is just there to keep the skins apart. The skins do the work), but nobody is building airplanes using from foam, primer/paint, and screening material.
- Foam covered with fiberglass and epoxy is not hard to do at home and makes very good structures. I don't know how well cabinets made using the techniques shown in the video would hold up to real-world use, and if you want them to look good it would take a LOT of finishing/filling to get there. Also, with this type of construction, any place where a "point load" will be (hinges, the place where the cabinet is hung on the wall or attached to the floor, places where shelves will be, etc) needs to be reinforced. That is usually done by removing the core material (the foam) in that place and providing something beefier (some wood, or epoxy with fillers in it) for a fastener to grab on to, and which can spread the load over more skin area. It's not hard to do, but it is best done during the initial design.
- Over at the "Teardrops and Tiny Trailers" site there are a lot of folks who build their own lightweight trailers using foam and fiberglass, as well as cheaper methods using foam covered with cotton cloth and this same "Gripper" primer shown in the video. Others substitute "Tightbond" glue for the primer. Where wood is used (floors, etc) they generally heavily drench it in thinned polyurethane to stop it from absorbing water. It seems to make some pretty good trailers that hold up to the weather (especially if covered with some good paint). But, if there's no "hard" exterior shell formed with something sturdy (e.g. fiberglass cloth in epoxy), then bumps from any object can leave a dent in the foam. Maybe not so good for lower cabinets in a trailer that get banged around a bit.

I stand corrected - checked the invoices from my plastic supplier; the material I use is Extruded Polystyrene, or XPS; it's a closed cell foam. It is white. Too many Es.....

http://ww3.owenscorning.com/sciencedoesntlie/

[Mike Magee]

Basalt roving might function well as an alternative to glass fibers, when coating sheets of this stuff.

[Jann Todd]

Originally Posted by Donna D.

Travel trailers are like earthquakes going down the road. I wonder if this stuff would turn to powder after a while?

I don't think it deteriorates very fast but he did say that you can't use screws since it won't hold them. I've used this stuff for insulation in a place or two and it works and does hold up.

[Patricia D.]

I think that most Ventura owners, when doing rebuilds, have used the rigid foam (Dow or similar brands) for insulation rather than fiberglass and it makes the whole trailer feel more solid.
I am thinking of using the foam for the structure of the cabinets but using 1\8 in. ply for the front frame and exposed ends.
The fellow in the video did say that he uses drywall screws to put the shelves in to hold them before reinforcing and he insets wood blocks where the hinges will be. He uses 1/8 in luane for the doors with one thin strip of wood, probably a trim of some sort, to stop warping. For the finish he uses paper covered with varathane and it actually has a wood finish look. There is a second video that shows the finished cabinets.
I was just intrigued by the idea of really light method of construction.

[Roy in TO]

Originally Posted by Patricia D.

I was just intrigued by the idea of really light method of construction.

As am I. This has me contemplating ways to replace the really heavy bed/table in the boler.