Lightweight vs. Sturdy Build

[rccoulter]

Hello folks!

First-time poster here. I've been reading this forum for a couple years now, and searching/browsing it has answered SO many questions. But I'm FINALLY about to start my build and I'm kind of stuck on one important decision.

Is it better to go lightweight or opt for a sturdier build for a SMALL trailer?

I'm building a 4.5 x 5.0 foot gear hauler over a 40"W x 48"L aluminum, bolt-together trailer.

I'm waffling between to different methods.

1: All floors and walls made from 1x2s and foam board sandwiched between 1/8" Baltic birch plywood (I've already got all the wood for this).

2: Floor cut from a single piece of 3/4 plywood, and walls/ceiling made from 1/2 plywood and 1/8" Baltic birch with hollow walls for wiring (I would just have to purchase the 5' x 10' sheet of plywood for the floor).

Lightweight Build
PROS
Lighter weight
Less expensive

CONS
More fasteners = weaker joints in floor
Less strength to support 6" overhang

Heavyweight Build
PROS
Stronger floor
More mounting options inside
Added strength to bolt-together trailer

CONS
Heavier*
More expensive

The trailer is rated for 1000lbs. The lightweight build would come in around 100 lbs. while the heavyweight build would be around 225 before adding all the extras.

This is a pretty small trailer. It will have a galley in the back, but the front will be mostly used for storing bulky items like tents, sleeping bags, sleeping pads, a big cooler, and a spare tire. On top, I plan on carrying two adult and two kid-sized bikes.

*So, is heavier really a con in this circumstance? Would the sturdier, heavier build actually help the trailer track better? Is the waterproof plywood enough, by itself to justify the heavier build?

I'd appreciate any opinions--I'm anxious to get building, but totally stuck!

[Pmullen503]

How tall?

Do you plan to cover the wood (aluminum, canvas, fiberglass?)

[rccoulter]

Good questions.

The box will be 3.5-4' tall, so around 5-5.5' tall with the trailer.

I'm planning on doing .025 aluminum on the roof, and either PMF or aluminum on the sides.

[tony.latham]

I'm planning on doing .025 aluminum on the roof...

That, as you might know, is awful thin stuff. Teardrops are usually skinned with .040.

I'd be concerned with dime-sized hail. Maybe even pea-sized.

Tony

[BigDave_185]

125 lbs being the difference, What is you tow vehicle?


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[rjgimp]

125 lbs being the difference...

125 pounds can equal a LOT of gear.

[MickinOz]

My thoughts:
Having weighed the pros and cons, I'd go with option 1 - framed and clad with 1/8 ply, since you have the materials already.
Fasteners in the floor ain't a problem.
I'd have the 2 x 1 on edge so that the long face is vertical.
I'd have the perimeter frame, and three internal cross members, so the ply is only spanning around 15 inches centre to centre.
Then glue and staple. This won't weaken anything.
The resulting torsion box is going to be remarkably strong and resistant to twisting.

I'd consider two layers of 1/8 ply on the floor top surface.
I just think 1/8 ply would probably be easily punctured by localised point loads.

There is a bit of a problem with the plan though.
You are planning to overhang the trailer frame by 6 inches fore and aft, 4 inches on each side if I have read your post correctly.
If you were to build the common floor frame then across one way, there are three cross members adding strength. The other way there would nothing to prevent flexing. Bit of an issue I think.
I think that I would do something like this for the internal frame of the floor.
Not to scale of course and its only a first draft, but if you want to build a light hollow cored floor, then there should be solid wood framing crossing the trailer frame all the way around, I think.

[rccoulter]

I'm planning on doing .025 aluminum on the roof...

That, as you might know, is awful thin stuff. Teardrops are usually skinned with .040.

I'd be concerned with dime-sized hail. Maybe even pea-sized.

Tony

I didn't realize it would matter, over wood. But I can totally switch to .040. Thanks for the advice.

[rccoulter]

125 lbs being the difference, What is you tow vehicle?

My two vehicles have ratings of 3500# (primary and 1500# (occasional), the trailer itself is rated to 1000#.

[rccoulter]

MickinOz:

I was thinking along those same lines. But without putting the 1x2s on edge. If I do that I'll just have to add some 2x2s for where I'm bolting it to the frame (see attached image).

TRAILER_FLOOR_SM.jpg (106.66 KiB) Viewed 1506 times

I've got to admit, I think I might be talking myself out of the sandwich floor the more I look at the design. Looks plenty sturdy, but it sure is a lot of work to save 5 or so pounds (~44lbs vs. 50lbs). When I was thinking of laying the 1x2s on their side, with only one layer of 1/8" on top, the weight savings was almost half (~26.5lbs vs. 50lbs), but I can definitely see where that wouldn't be strong enough, especially with the overhang.

I can still save quite a bit of weight doing the sides as a torsion box though.

Thanks for the input. That was really helpful.