What is stronger for ramps/resist bending (3) 2x4's, (2) 2x6, or (1) 2x12?

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Forum topic by Sparkynutz posted 11-12-2013 06:20 PM 6433 views 0 times favorited 3 replies Add to Favorites Watch
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1 post in 1680 days

11-12-2013 06:20 PM

Topic tags/keywords: bending strength of lumber sizes per same width

I frequently transport heavy materials in my truck bed that stick past the tailgate and want to make some supports to take some of the load off the tailgate. Tailgates are known to buckle if overloaded and I want to prevent that if possible. I’m looking at using fir or yellow pine #2 or better lumber to save on cost, but haven’t decided on dimensions to use yet.
Would multiple smaller boards resist bending better than fewer wider boards or vice versa?
I’m laying them the flat way front to back with a single 2×4 on top accross the front bolted down to the truck bed.
I’m not interested in standing them up edgeways and making plywood boxes or anything similar as I’d lose more bed room than I’d like.
My other idea is using a single sheet of 1-1/4” 17 ply marine plywood or similar, but doubt it would be stronger than the lumber.
What do you guys think?

3 replies so far

View Rex B's profile

Rex B

320 posts in 2274 days

#1 posted 11-12-2013 07:14 PM

It depends whether you mean multiple boards stacked or side by side:

If they’re side by side, they have the same thickness and a 2×12 is wider than 3 2×4’s; hence stiffer. If you’re willing to stack them, 3 2×4’s would be much stiffer than a 2×12.

Either way, you are correct, solid lumber would be stronger than plywood for this.

-- Rex

View Tennessee's profile


2873 posts in 2538 days

#2 posted 11-12-2013 07:32 PM

I think I’d be looking at a couple of pieces of 1”X1”X1/4” angle iron, laid open end down.

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

View crank49's profile


4032 posts in 2995 days

#3 posted 11-12-2013 07:37 PM

If I understand your explanation you are sort of making a table top in the bed of your truck out of 2x lumber with a cross brace on one end.The table top will be longer than the bed so it can extend out past the tailgate.
Is this about what you mean.?

If so, it makes no difference whether you use 2×4s or 2×12s as long as they are equal quality and type of lumber AND all the boards are joined together in some fashion and the assembled width is the same. Glue & biscuits or pocket screws or whatever.

If its every board for itself, then use the widest boards you can get because solid is better than strands.

There are many more efficient, lighter ways to do this, but I would have to know what is being hauled to suggest a proper design.

One fairly basic idea would be to build a torsion box design having 1/2” skins of marine grade plywood and a 3/4” thick grid between the layers. Built with waterproof glue and screws. This would carry about 30% more load than just glued together 2x boards.

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