I want to build a 24′ x 48′ garage / workshop using pole barns (tri-lams) for the columns and a finished concrete floor. The area I live in is “marshy” and prone to low level water accumulation during heavy rainfall. Most of the locals bring in fill dirt to build up a mound, then pour the slab on top of the graded mound. This takes quite a bit of time to allow for natural dirt settling. I was wondering if there was a way to pour a footer and build up a stem wall with CMU’s, back fill with gravel, then pour the floor. I would, of course, have to have some sort of ramp to get into any one of the bays. Anyway, just looking for ideas for an elevated workshop to keep my feet dry ?
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You can substitute gravel for the fill dirt, and if you make the fill area larger than your building, you would not need the knee wall. just put the slab on top.
might work best if you push some of the existing soil out of the way, and use to grade the sides of your gravel pad.
cost is likely a driver of using fill dirt. Might want to call around and see what is available for what cost.
someone might have a large compactor they would come use for site prep as well. Or you might be able to sweet talk some kind of a deal with the local road authority. Will want to talk to them about a driveway cut at some point. Plan the whole job, including a good driveway to get to the garage. no sense having a dry garage and a swamp to drive through to get to the road.
Ok, thanks. Right after my post I found this picture through some random searches of a stem wall. This is what I had in mind although not quite as tall. Perhaps one or two courses of block. I was thinking of anchoring a sill plate on the block then bracketing the posts to that. Thoughts?
I guess that makes sense if you don't want to increase the elevation outside the garage.
I don't think you need a sill plate, and will have to look more into support for those columns. I want to say it is not a given that a sill plate would spread the point loads from your columns to an otherwise unsupported CMU wall.
Would be better to bed anchors into filled cores of the CMU. Might have to size the CMU for this purpose. specifics will take some figuring. do you have an engineer to look at the design?
You can do this in a monolithic pour. Form the outside of your stem wall with what ever form material you are using. Form the inside with drywall scraps. Place all your steel then put spreaders of 2x scraps between the forms, You should then be able to backfill and compact against the inside form if you are careful. Then pour. As the concrete level comes up inside the forms remove the spreaders and stakes holding the drywall. The drywall stays in place. I've been in places where they would leave the spreaders in place but I don't recommend this.