Question on steel...

[hrace18]

I am getting ready to tear down and rebuild the garage/shop at my dad's house. The original building is 24' wide x 30' deep with an extra slab next to it that is uncovered. We installed a 4 post lift on the uncovered slab and plan to cover the whole thing now, will end up being 40' wide x 30' deep.

I am going to be doing it myself to save money, plus I like doing all my own stuff anyways! I am looking at doing a single sloped roof going from 14' where the lift is down to 12' on the other end.

My main question is what size posts should I use for the main structure? I was thinking 3"x3" or 4"x4" 1/4" thickness. Since I already have the slab I was thinking about welding plate to the bottom of the posts and bolting them in with concrete anchors. What should I use for the rafters and how far apart should they be?

Sorry for all the questions, but I just want to have a plan when I get everything together.

 

[Torque1st]

You need to find a structural engineer. If you live in a city or area with building codes your local codes enforcement people will be looking for a PE stamp on the plans.

 

[hrace18]

He doesn't live in the city so I don't need permits or anything like that. Mueller is not too far from where he lives, so I have requested a quote from them for a building.

 

[38Chevy454]

Either of the posts you have suggested are fine, bigger is better, but it also costs more. Either is much stronger than a 4x4 wood post. The foot plate and using anchors is fine, the anchors are only holding it in position; the load is vertical through the foot plate. It is the distance between the posts and the header piece that you need to worry about. Your local codes will dictate what size header and rafter size and spacing you need.

 

[robertlynk]

Is the old building wood or steel ? If wood you will have to put up a steel building with the same configuration as the wood building because of the loading of the concrete. if the building is steel follow the same pattern. With a standard steel building the main roof structure is supported by the center columns where as a wood building spreads the load along the entire length of the foundation. So I think for safety you should have the foundation check to see if it will support the load of which ever type of material used

 

[Charles (in GA)]

It sounds like part of your slab was simply an open pad that I'll bet had no perimeter foundation, so it would not be designed to support any kind of building.

Charles

 

[KEH]

If there is doubt about the strength of the original pads i would dig new footings around the existing pads and make them proper depth with rebar.

Keh