Making a monolithic slab

[paintman161]

I live in western NY and our ground is mostly sand and a few small stones, easiest stuff i have ever dug through. I want to make a monolithic slab for a 20'x24' Garage. It will be all stick framed and use garage trusses. Has anyone here any experience designing and pouring one, would like all the information i can get. I will most likely bid the foundation out, i just need some ideas as far as plans go to give to the town for a permit.

[Richard A Hetzel]

It's really best to separate the foundation from the floor slab. There is no real advantage to a monolithic foundation, and there can be some drawbacks. If it isn't carefully designed, you can get cracking around the perimeter of the slab. I don't know what the bearing value of your soil is, but with a light structure of only roof load, you may be able to use a wall whose bottom is wide enough to also serve as a footing. Build those, then come back and put in the slab later. It's the best way to go.

[Brock]

and having a stemwall allows you to slant the floor front to back. makes it nice to hose out.

[concretemasonry]

Also block stem walls could be 6" or 8" above the low floor point and the slab can be sloped for drainage and washing out. This is definitely the preferred method here unless it is a cheap GC.

The projecting stem wall gets the wood up and away from the water, salt and goop and makes it very easy to clean or wash out after a winter of collected slop and debris.

Also, with footings below the frost makes it more resistance to any frost heaves over time.

Dick

[doityourselfer]

here is a website that will tell you everything you want to know about pouring concrete on grade and how to do it without getting cracks
concretenetwork.com/concrete/foundations