Plywood Question

[captndiet]

I am finishing up the mechanical repairs/maintenance on my 2002 Dodge 3500 Extended High Top Van and will be starting the interior build shortly.

My question would seem to have an obvious answer, but I have been researching it and have not come up with one.

What plywood to use?

There are many different grades, finishes, plys, type of wood, and thickness available.

I will be putting one bed on each side wall at the rear, (28" x 79" each) which leaves 13" between them.

I will hinge the platform lid to allow access to totes underneath the beds.

Menards is my closest lumberyard. Here is a link to their choices for 1/2" plywood.....

https://www.menards.com/main/search.html?search=1/2"+plywood

I am sure I left out some important info.

Thanks for the input.

Jeff

 

[Beeps and eats]

For bed's I use 3/4" osb plywood, the finished side up the rough side isn't viable anyhow. And it's less expensive. But 1/2" is too flexible in my opinion.

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[bullfrog]

For bed platforms I have used cheap damaged interior doors from big box stores. They come in a 28" width and are 80" long new. Lots of them at recycle stores have been cut for carpet and can be had for a few dollars. Take your tape measure and you may find one the perfect lenght. By glueing a piece of thin plywood (3/16" or 1/4" birch) on top to cover any holes or damage a 200 pound person can stand on them. The smooth surface of the cabinet grade plywood doesn't catch or poke air matresses or give you splinters as much as construction plywood would and because it is thiner it costs less than most thicker plywood. I have also used Luan with good results but it is not as strong. This method weighs about the same as the thicker plywood but is much sturdier as it ends up being about 1 3/4" thick. Hinges can be mounted on the sides so nothing sticking up on the sleeping surface. I paint the whole thing with semi gloss house paint to prevent mould from condensation and possible water damage. I use interior doors lots of places instead of plywood like counters. You can use dowels held in by glue or spray foam to mount or make it really strong you can cover them with glued on drop cloths covered with paint. My whole camper trailer is made this way and has held up outside well for years so I know it will last inside your van.

 

[Almost There]

captndiet

What plywood to use?


Jeff

That depends on the support structure you  have below the bed top, in particular the largest span between uprights and how you framed it out and the weight load you expect it to carry.

I used 1/2 plywood as dividers between all my compartment sections of the bed frame. Turned on it's narrow edge, plywood is extremely strong. I then used 5/8 plywood for the top because the largest span is about 24" x 45" and is right below the middle of the bed where it's going to be supporting the most weight. 5/8" is sufficient for me because it's only me and I'm under 200 lbs.

Tell us more about the support structure and the weight load and we can give better advice.

 

[highdesertranger]

yep plywood webbing is better than using 2x4's and such. I would also use real plywood. highdesertranger

 

[Canine]

There are different grades of plywood. Ideally get AB or underlayment as they have all the holes fill in. Plywood can have a lot of voids inside of it because knots fall out. Underlayment is cheaper, too. I painted all my wood and have no issues with splinters. One time I used 5/8 plywood and it was plenty strong enough for my narrow behind, but this time I used 3/4. Plywood takes paint much better than OSB. OSB will flake up and leave little pokeys that will catch cloth and such. Plywood will be smooooth and look better, too. Plywood holds screws much better, too. OSB will work, but it is less than ideal. I recommend plywood for sure.

Sometimes a bunk of plywood will come in with a corner busted off or otherwise damaged. If you don't need the full sheet, that can be had for much less. It's worth asking.

 

[captndiet]

I had planned on plywood for the base.

The ends will end up being 24" - 26" tall. The base approx. 15" tall. The mattress' are 5 1/2" thick.

Had planned on base divider at the half way point. (39 1/2")

The totes I have are 13" tall.

I am 220# & Sue is 150#

Jeff

 

[bullfrog]

I have used the totes as a base with a 1/2" piece of plywood laid on top. You can still slide one tote at a time out with out any thing being disrupted.

 

[Beeps and eats]

One thing I have learned in building beds is you never really know what you need, one bed I built for a woman who weighed 84 lbs and was 4' 9" and one for a man 6' 4" and 270lbs it's really a matter of engineering the bed for the job it has to do.
The first bed I mentioned was 1/2" ply and needed very minimal framing. So it was fairly light weight. The second one was 5/8" ply and 2x4 framing with ply reenforcement's in the center and ends to prevent shifting and sagging. So my advice is to build for strength and keep the weight in mind. We all have different body types and that's going to be the determining factor in the bed build. But that's what makes each build unique, they are a representation of the owner.

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[WanderingBiker]

Over engineer it and build it once, under engineer it, build it twice

 

[MrNoodly]

For bed platforms I have used cheap damaged interior doors...

I built the equivalent of a hollow core door. A sheet of 1/4" ply glued and screwed to a perimeter of 2x2s with additional 2x2 cross pieces also glued and screwed. Then another thin sheet of plywood laid on top so I could store flat things inside. It works great, and I'm a heavy guy.
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[Canine]

MrNoodly, very nice. Outstanding use of space. And strong.

 

[highdesertranger]

there is absolutely no reason to use 2x4's, 2x6's, OSB, and particle board. they don't use any of that in better RV's and Boats. learn how to build stuff right, with plywood webbing, it will be lighter and stronger. you can build an airplane out of plywood, 1x2's, 2x2's and lathing. highdesertranger

 

[bullfrog]

One complaint I have about thick (5/8" or thicker) is I have a hard time waterproofing it. I've used the mix, Thompsons, polyurathane, fiberglass, roof sealant and still if exposed to water long enough it seperates at the glue joints usually at a corner. Granted most has out lasted the screws I put it together with which is why I started using wooden dowels and Tightbond III or Gorrilla Glue after the glue dried and the screws were removed. Waterproofing and covering with Poor Man's Fiberglass is as close to perminent as I've been able to accomplish. Places where I would have in the past used 2"x whatever I now use a 1"x2" on top and bottom with a 1/4" groove running the lenght for a 1/4" piece of plywood on edge a 1/2" wider than the width I need glued together as sort of "truss" they use for floors nowdays. Much lighter and stronger and if you cover the ends of the plywood with PMF it will last. Be careful about putting carpet or anything that will hold moisture on plywood as over time in will cause problems. Even boat builders have to occasionally do repairs.

 

[bullfrog]

MrNoodly I do the same thing for thr floors of my trailers with the addition of spray foam in the cavities and PMF on the bottom or outside.

 

[BelgianPup]

Could someone please explain what "plywood webbing" is? It sounds good above, but Google doesn't seem to recognize the term. Does it have another name?

Thanks!

 

[Matlock]

Same plywood just turned vertical to support the horizontal pieces of plywood. Use instead of 2x2's for structure frame.

 

[ridgeway]

I worked as a rough carpenter before I will not use OSB for anything I make for my self, I have seen too much of it deteriorate with just a little water and moisture.


--Common grades of consumer plywood- The letters tell you the quality of the layers of the woo
ACX- the first layer is high grade you can put a finish on it and it will look nice
CDX-  the first layer is a little rough, it will take more sanding to make smooth you might get a splinter from time to time.
OSB- Glued wood chips, the top layer will always look like glued wood chips. If it gets any significant water it will swell and be ruined.

Why is OSB used ? It is cheaper. In large applications like a home it saves thousands and most of your home is protected from water. Also most of the OSB will have a covering such as tile, hardwood, carpet. For a van and a few sheets plywood it is not worth saving $20-$30 IMO. You are investing a lot of hours of labor and time.

--Plywood thickness
Most of the time I use ¾ plywood for stuff I do not want to flex such as a bed. For a van and weight factors I am using 1/2" if you run a support every 18” ½ plywood should be plenty stiff. If you run ½" bigger then an 18” span you might want ¾".

 

[maki2]

Could someone please explain what "plywood webbing" is?  It sounds good above, but Google doesn't seem to recognize the term.  Does it have another name?

Thanks!

It does indeed have a real name for that type of structure and you are correct because it us it is not in the world of enginerring definitions known as " plywood webbing". Its official name is "stress skin panel" construction.

To make a stress skin panel there must be a continuos adhesive  bond between the piece of skin material and the other structural supporting pieces.  A hollow core door in a house is strong enough for its purpose because it is made as a stress skin panel. It can be a bit tricky to get a good  bond between the pieces if your materials are not truly flat and if you cant apply weight on the panel while the adhesive cures. But using a few mechanical fasteners can help to keep things pulled together while the adhesive develops full strength. Remember full strength bonds require days of cure time, not just a few hours of time. So don't get in a hurry and think you can slap it together and use it that same day or you might get adhesive failure. Read the instructions on the adhesive and pay attention looking for the time required to develop " Full strength" and dont put stress on it until after the adhesive has fully cured.

 

[user 423]

Could someone please explain what "plywood webbing" is?  It sounds good above, but Google doesn't seem to recognize the term.  Does it have another name?

I'm not sure of the proper name but I thought it meant cutting out excess material to lessen the weight.

Vertical plywood supports for a bed,etc. would  be very strong but you could remove quite a bit of the inside and it would still be strong.

Cutting holes in plywood used for the bed surface with a hole saw would provide air circulation and help with limiting mildew.

And it would reduce weight.