Issue with shop floor

[Exceller8]

I have a 16x20 Tuff Shed as my workshop. I have a concrete foundation but the shop is sitting on a roughly 2x4 galvanized floor frame (shown in link photos) with plywood on top. My issue is the with my fully loaded HF 56" box the floor is starting to sag. Nothing major but it has me a little worried.

I know I could unload everything move the box cut the plywood out and fill with concrete and put the plywood back, but I was looking for other ideas. Leave it as is? secure it to the wall?

What would you do?

Thanks in advance for any help!

http://www.tuffshed.com/photo_galle...19144077&SetName=Storage Sheds - Garden Ranch

 

[Streetbu]

I'd add at least another layer of 3/4" plywood, maybe even too. The box fully loaded will weight more than you think, and all that weight is on 4 casters with about 1 or 2 square inches total contact each Your ground pressure would be around 500lbs per square inch. That's huge! Or maybe a 1/2" steel plate at least a foot square under each wheel to help distribute the weight some more.

 

[Garage Flooring]

First of all I would give them a call and see what the capacity is. If you are exceeding that capacity understand you do so at your own risk... BUT

There are several things you can do. The Plywood is probably not really the problem. If you are going to add more plywood, use a 3/4" or even an 1-1/8" Sub-floor material but run the grain the other way.

An even more effective solution, if you can access it is to get to the underside and add additional 2x4 material. You could either add one between each existing joist or even put it in like you would do header material. Then screw through the plywood into the new joists.