I chose to go the cheapest, most involved rout of doing the majority of the work myself, and overseeing the work I didn't do. I have time, and the ability to do the work. I also enjoy doing these things.
I really did look at doing a poll building vs a steel building. The price for a wood building was more expensive than the Mueller building I purchased. Trusses were also very difficult for me to source, and I'm not going to make my own that span 30ft. I did the steel building because it is an engineered building with all the load calculations already done. One of my neighbors built their own garage and it collapsed in a big storm, I don't want to take that kind of chance.
I chose to do a monolithic slab with anchors drilled after the fact, it was the cheapest pour labor wise for me. Pumps, conveyor, or buggies are needed if you do a pour after the walls are up. Pumping also changes the mix and increase price on the raw material, at least it does here. I decided to do drilled anchors after the fact because I was worried about a potential blow out or accident shifting my templates and causing bigger issues.
Important things to consider if doing it yourself.
I purchased the building direct from a manufacturer, and set up delivery. It was my responsibility to insure the delivery truck (40ft semi) was able to drop the materials where I wanted them. I had to cut part of my gate so the material would fit through. Otherwise they WILL drop it on the side of the road.
I did all the foundation prep. I ordered the ABC, layered, and compacted it all to grade with a skid steer I already owned. I didn't have a fancy laser level so I made myself a water level. I rented a mini excavator to dig the footers, etc.
I set the forms making sure they were square and strong enough to withstand a bump here or there and not blow out. Laid out, tied, and put the rebar on dobies because "pulling up" is unreliable in my experience.
I was super worried about getting a good pour and finish. Being that I did all the prep work, which is vital to a stable and strong slab, I waived any warranties. I reached out to 2 concrete delivery companies and asked for referrals. I reached out to all and made a spreadsheet. I asked them all detailed questions about the process and ran away from the ones that said they would add water here or there, or spray it with water. I also inquired about how they would handle the 100+ degree day pour. The most knowledgeable just happened to be the cheapest, and was actually a driver for the company. All of the companies listed on Google were either not interested or expensive, $5000 in just pour and finish labor.
I had the guy doing the pour set up the batch how he liked it, I verified it and paid the plant directly after addressing any concerns.
They came, poured, and finished. The slab looks amazing, and there were no issues during the process.
My red iron building costs so far.
30x40 red iron building delivered ($10,500) Bare kit no insulation or roll up door, just an opening.
24 Tons of ABC ($750)
Compactor Rental ($200)
Excavator Rental ($300)
Concrete Forms and Stakes ($600) Crazy high wood prices!
Rebar, Rebar Chairs, and Wire ($1000)
Concrete labor ($1600)
30 yards of Concrete ($5200) Hot weather + high flow = $$$ Water reducer, cold water, fiber, all adds up.
Saw rental for cutting joints ($100)
Anchors ($400)
Scissor lift rental ($650) I was hesitant to spend this but it would have been impossible to get it done without it.
If I didn't have my own skid steer that would be another $1000.
I'm around the 23K mark with all the small nickel and dime expenses not captured here. Several Turn key red iron buildings of the same size were quoted 38k to 50k, minus the concrete. Several of the modular tube buildings were quoted at 20k for erection on a slab that was not included in the price. Several concrete contractors wanted 8k to 10k in just labor for site prep pour and finish.
If you have any specific questions let me know.