I’m fixing to run a driveway down the side of our property…it’s currently lawn. Eventually we’ll pour a concrete driveway, but that will come after the garage is built and that could be a year or two, I imagine. There’s 15′ between the house and property line, 3′ landscape buffer required and an 18″ overhang on roof… leaves me with a little over 10′ for drivable part of driveway.
To allow access, I thought I’d get the sod out and the road base down so it’s driveable for the time being. I’ll also run gas and sprinkler feed line into back yard.
Clay soil for the most part…southwest Idaho. I was watching it move around under weight of a backhoe while doing some other work…reminded me of silly putty!
And finally, my questions:
How deep should I cut down the existing soil and what would be best to replace it with given the soil conditions? I only want to do it once.
Should I build it up to approximately finish grade and then cut back when we do concrete or leave it shy by about slab thickness?
And last, what’s the wisdom on putting slab against foundation vs leaving a space between. Top of footer is about 18-20″ below grade and my concern would be undermining it if we excavate right next to it.
What say y’all?
PJ
Everything will be okay in the end. If it’s not okay, it’s not the end.
Replies
The gravel bed should be a foot plus, check local codes. The bed should be of at least two types of gravel or rock: larger 2 or 3 inch topped with 1 1/2 modified (stones mixed with fined that compact very well). Insure that you roll the stone every two inches or so and not all at once. The effective compaction of a roller extends only an inch or two down, so if six inches of stone are rolled only the top skin is compacted properly leaving the rest susceptible to heave and washout, leaving you with a moving base for whatever drive surface you choose. Preparation is 90% of finish work.
The sub-base can be a combination of 3-6" net and 2-3" net, in 2 layers, starting below the frost line and coming up to 19" below finished grade. The sub-base needs to be about 1-1.5' thick for light vehicular traffic.
The base is made of 12" of ¾" net, and finally 4" of 0-¾". The last 3" below grade are for the concrete slab to come.
Since you won't be pouring the slab for a year or two, don't get neurotic about the compacting; some natural settling will occur through two years of car traffic and a couple of freeze-thaw cycles. Still, do compact mechanically now, in small lifts. You'll get a better job. Expect to add a bit of 'top dressing' to fill in the ruts and to compact that just before you pour the slab.
You definitely do not want to undermine the house footings. Stay away from them if at all possible. If you must dig there, shore the trench sides as you go and be careful.
I would leave a decent space between the driveway slab and the foundation wall of the house, too. These two concrete elements are each in a different plane, and expansion will be differential. You don't want the driveway slab pushing laterally on the foundation wall in the heat of summer....
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Wow, been more than a year since I posted this and finally getting it down to the short strokes...slow but sure, I guess. Thought some might be interested in the progress.
Where we started
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Then a retaining wall on property line
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Trench for gas line, will supply shop and eventually house
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Dozed some dirt out
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Pit Run, lots of it. Four trucks and pups...96 yds. We had one big patch of hungry, pumping clay
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Will get topped this week with 3/4"road mix
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PJ
Everything will be okay in the end. If it's not okay, it's not the end.