I've got an existing asphalt driveway that's around 20 feet long. It's in fair shape. I want to widen it by about 5 feet. The ground is level, I'm in the soggy Willamette Valley, Oregon so frost isn't a big concern. And the plan is to have it used for occasional parking.
Is laying down 6" of 3/4 minus gravel sufficient? Should I use larger gravel?
Is there anything special that needs to be done at the junction of the gravel and asphalt?
3/4 minus (21AA in US Midwest) is perfect for this application.
Hope you have some college kids around, that's nearly 2 cubic yards!
I would overdig another 6" to be able to place an edging to retain the gravel and make a clean edge.
Place the gravel in 2" "lifts" (lay down 2") and then compact with a plate vibrator. Repeat twice. Enjoy!
6" compacted will be quite solid and stable.
Update
This edging can be backfilled with dirt to grow grass. Just place it when you are 2 1/2" from the top. Its usually staked with landscape nails every 2 ft, but I'd do it every foot. I know you're not using pavers, but this will retain the edge of the gravel. You don't have to do anything with the asphalt edge, unless it is rolled over unevenly, in which case you can cut it with a masonary blade in a circular saw.
