Building garage 24x30 - help me!

[going88mph]

Hello,

I'm building a 24x30 garage in my back yard (metro DC area). Have the permits approved already. The estimates I've been receiving for the concrete foundation & floor have been very high ($9,000 - $21,000). I am considering doing the excavation myself, which I'm told from the contractors would reduce the cost by about $5,000-$10,000.

County code calls for 24" footing and a 4" floor, which is what I plan to do with a monolithic pour. Can someone help me figure out the correct sequence of steps, or maybe recommend a book? I can rent all of the equipment (bobcat, backhoe, etc) locally. More specifically, what I'd like to know is the order of steps, i.e., first remove the topsoil, then level the 24x30 lot, then place the gravel, then dig the footing, etc.

This is the foundation plan I'm going for:

Any help is appreciated.

 

[camarotoolman]

next build your forms, don't fegot to pitch to the doors so rain will run out, put down vapor barrier, rebar and wire mesh, ridid insolation. Pour slab. I would hire an expeinced guy or two off CL to help, just pay them by the hour.

 

[BillK]

88,
That is exactly how my 24 x 24 detached garage is built. Dont know where exactly in the area you are, but I am in Waldorf. I would call around and get a couple of more estimates. Things are pretty slow in construction right now and you may be able to get a better deal ??

When I built mine 25 years ago,the foundation was the only thing I did not do myself. I think the most important thing is to get the base correct. Mine has one small crack that only showed up a year or two ago after an extremely dry summer.

The only thing else I would do is make it 5" instead of 4". The added price is very small compared to the overall project.

 

[Angelfire]

What's the history and make up of your soil? Around here, overex and compaction is pretty much a requirement. For a 24" footing you should be going down about 4' then bring it back up in lifts while compacting, if the conditions require it.

 

[Falcon67]

And over here, all footings have to rest on undisturbed soil. So read the county requirements and do that. And for a 24x30, you'll need at least 2, better three guys that know what. Better to let the concrete company provide experience labor. You'll be damn sorry about using anything less. Nothing quite like 68,000 lbs of concrete with a bad finish, dips, who-knows-what.

Around here, it's typically
Level
Dig footers (small here - 18" wide by 12" deep on a house)
Forms
Sand - level and pack
Rebar place and tie off
Inspect
Pour