which plywood for truck bed sides?

[newbury]

I DON'T WELD
On my new to me toy, my F350 DRW 7.3L 4x4 I wanted a ladder rack, for rare use. The used ones on CL etc. didn't look adjustable.
Trac-One has a decent adjustable frame one for $300 BUT IT DOES NOT FIT Superduties, my cab is too high (plus I've got running lights on top).

So I went to my basement, and with a few 2x4's and connectors I've built a frame that will START to meet my needs. Six stakes, 3 crossbeams, clears roof by several inches, no pics.

And I'm looking at it and thinking I could enclose it w/ removable plywood sides running to the top to increase my load size as I "ferry" stuff down to my retirement home. Basically a removable set of walls with a tarp strapped on top.

I'm not planning on using it for hauling firewood or stone, just cardboard boxed household items.

So my question, for any of you that have done similar - What thickness and type plywood do you think I'll need for 70mph and rain? Will half inch do? Do I need to go to 3/4? Pressure treated? Marine?

thanks

 

[Diamondpilot]

I would use marine grade 5/8.

Chris

 

[LD1]

Definatally need PT or Marine grade. And its expensive.

I think half, 5/8, or 3/4 would all work just fine. Just use pleanty of screws.

 

[JDgreen227]

What kind of service life do you expect? 1000 miles? Six months? A dozen trips? It doesn't sound like you will be wanting long life, so I would go with 1/2 inch CDX doubled up. REAL plywood, not that cheapo OSB S*** and use fender washers under the screws to give them more holding power.

 

[radioman]

I agree with all the posters here, but it all boils down to how long do you need it for? or are you planning on leaving it on the truck lifetime?

I have many times in a pinch carry firewood with full sheets 7/16 OSB on a flat bed truck. When the firewood was dumped, the drywall screws taken on and sheets were taken off for double duty use around house. I put the OSB sheets on the inside of 2X4 stakes with screws. Easy on. easy off. no problem.
If you are in a need to have a supply of OSB sheets or whatever you need at retirement home- this sounds like a good solution - if not perfect.

 

[CurlyDave]

I DON'T WELD
On my new to me toy, my F350 DRW 7.3L 4x4 I wanted a ladder rack, for rare use...

I am not going to help you with the design, but as an engineer, I will point out that the force on anything exposed to wind increases as the square of the speed.

To keep it really simple, if you are rarely using this, keeping to below 50 mph will reduce the forces on your rack to 1/2 of the forces at 70 mph.

 

[newbury]

To keep it really simple, if you are rarely using this, keeping to below 50 mph will reduce the forces on your rack to 1/2 of the forces at 70 mph.

I understand the forces, and it will be directly behind the cab with only about 2 inches protruding above the cab.

How long?

Probably until the truck rusts into the Mississippi mud. Example - I built a bed for inside the back of my '81 dodge van. I've still got most of the bed, the van is long gone.

I'd EXPECT to use the box maybe 2 or three times a year. I'll probably want the rack more frequently to carry ladders or long lumber. I'm leaning towards 5/8 Marine plywood for the box IF I can find it locally, the big box stores (HD, Lowes) don't carry marine, the only close lumber yard has to special order marine, so I might go PT and paint.

The rack cost about $70, half for hardware and half for PT 2x4's. I bought a bunch of the metal angle brackets, should have used scrap plywood for angle braces.

Of course I don't know AND DON'T WANT TO KNOW how many federal, state, and local regulations I've broken by not having a licensed carpenter and licensed mechanic put it together under the supervision of a licensed architect and licensed safety engineer with an inspection by a licensed ladder rack inspector.

It seems very sturdy so far when subjected to both vertical and horizontal forces. I've yet to test in the windtunnel called I95.

 

[bcp]

I think the only difference between exterior and marine plywood is that the marine has no interior hollow spots where a knot was. The weather resistance would be the same.

Bruce

 

[crashz]

Remember that you will have forces pushing the sheeting out as you drive faster too. For this reason I would fasten the sheets to the inside of your framework, with a space cut in for your toolbox. It may not be as pleasing to the eye, but it will be very secure.

I can't tell from the photo, but also make sure that the frame is secured to the bed. This is most important when transporting anything that could become a type of sail. Probably easiest to use screws with large washers through the access holes in the stake pockets, so that the frame is secure and you don't need to drill into the sheet metal.

Otherwise looks good!

 

[Cat_Driver]

You're wasting your time building a rack out of wood. Not only do you need to figure the load but the forces involved with that load and road conditions. Hit a pot hole and that load gets doubled pretty quickly.
Used racks are a dime a dozen on E-bay craigs list etc.

Here's one for $260.00. You couldn't buy the lumber for that.

NEW CONTRACTOR PICKUP TRUCK TOOL LADDER LUMBER RACK | eBay