Structural differences between 4x8 vs 5x8

[DiabloCanyon]

I am finishing up the skin on my first TD which is a 4 x 8 and it got me thinking that the next time around if I tackle another one, I may do a 5 x 8. I was wondering what the structural differences were with regards to spar placement, extra reinforcements (if any), or do things just remain the same with layout? Is it necessary to upgrade to oak/hardwood for spars to add that extra bit of strength?

Thanks again!
Tom

[kirkman]

I did not make any structural changes when I built my 5x8. 5 years and still looking good!

[Mightydog]

The only structural changes we made were in the profile. We really didn't make any as a result of going five wide.

[dh]

Same here, nothing special, just made it a foot wider.

[David S]

I'm building 5 wide,used yellow pine 2x2 for spars,spacing is tighter on the sharper part of the curves,you mielage may vary.

[OuttaHand]

I am just finishing up a 5' wide. The biggest thing I can think of is the amount of plywood you'll need.

On your 4', for the roof, were you able to run one sheet wide and use the entire 8' length front-to-rear? If so, you obviously can't do that on a 5' wide. You might be able to find 5' wide plywood, but if you mount your side walls to the outside of the trailer frame rails like I did, that's going to add roughly 1.5 inches to the overall width. That means if you want your roof plywood to lay over top the side walls, you are going to have to use 8' long plywood and lay it sideways.

You can use some of the not-quite-3' long cut-offs when you're working on the interior and galley, but you will probably have a little more waste and expense.

[jdaan]

You might be able to find 5' wide plywood...

5x5 Baltic Birch is great if you can find it in your area. The price is a little higher per square foot than some of the other stuff, but you might make that up in reduced waste.

Justin