Steel working question

[TheDjost]

I'm planning on building a shed/mini-workshop in tha back yard, and the plans I have call for building out of wood. Now since I don't own the place, it has to be removable. I am adapting the plans to make the whole thing modular and dismantable, and one of the things I'm changing is the main building material. I'll probably build out of steel. More precisely, out of 2 inch square tubing.

What thickness do you think would be sufficient to hold a 5 or 6 ft span? The whole shed is built on a skid foundation. Two 6x6 wood beams laid on the ground will give me a solid and straight base. Since the yard is paved this should be sufficient. The shed will be 8 ft wide, so if I put the skids at 1 ft from each edge, the span will be 5 ft in the middle.

Inside the shed will be some moderate weight, since it will serve as a small workshop for tinkering around the bike, cars and other projects (tools get heavy).

Is there a rule of thumb as for what size steel tube will replace a certain size wood joist? I've looked at steel tubing tech specs, but i'm lost at all the definitions, and variables. I'm not an engeneer!

Anybody's experience, comments, hints, etc. are welcome.


-Justin

[Dragonrider]

Hmmm...for a floor span...

I am using 2-1/2" square schedule 80 (basically 1/4") as a boom arm. At 6 feet it will pick up 1500 pounds.

You should be ok with lighter than that, though you want to stay heavy enough that you do not get any flexing. Say, 1/8" wall?

My crane project is here (with pics):
Deck Crane

Good luck!

[fusionking]

If your planning to use 16" centers as is standard with wood then 14ga. should be plenty. Have you thought about std steel studs?

[TheDjost]

Daniel, I'm happy that you suggested 1/8" because I had already figured my pricing with 1/8" thick steel mainly for strength, but also because I am using a stick welder and I don't want to have too much trouble with burn-through. I was worried that 1/8 might not be enough and that I would have to go bigger, but since Garry suggested I go even thinner, I should be okay.

I just drew my complete plans today, and I'm going with 24" centers for ease of welding. At 24" centers, plywood sagging becomes a problem, wich is solved using cheap 1 inch angle as bridging between the beams to hold up the wood surfacing material.

Garry , If by standard steel studs, you mean something that would have the same dimensons as wood, then it won't work because I also need to keep the structure as low as I can. That was one of the things that pushed me towards steel in the first place. With a 6x6 wood skid, and 2x6 joists, the floor would be at least a full foot off the ground. Build up the shed with 8 ft clearance inside at the top and add the 2x4 for the roofing support and the whole thing stands almost 10 feet tall. Building in steel will save at least 8 inches off that. It doesn't seem like much, but then I don't want to have to cut some interior clearance to comply with city code of 9 ft for a shed.

The floor will be plywood. 2 layers of 3/8" glued and screwed together should give me plenty of strength to keep the floor from sagging.

For the walls and roofing, I was thinking about 1x1" 1/8" square tubing again all welded at 24" centers. What do you think?

-Justin

[fusionking]

3/4 would be a normal floor thickness. I say at least on the floor go with 16" centers or you might regret saving a couple of bucks depending on how heavy those tools are. 1/8th is harder to shoot a screw thru and 1'' means you better use short ones or you'll have problems if they are too long....just get the right ones. I would save money on thickness on the walls on roof and spend it on the floor myself. steel is sold by the weight so you should get a lot more 14ga than 11ga for the same money. Just a few thoughts off the top of my head. Sounds like your on the right track.....good luck