Two questions. On the top 12" of a driveway (it will be paved) should I use 3/4 gravel or 1 1/2 gravel ? Also ,I need to back fill the interior of a garage.(4' +-) Can I use 6" gravel for the first 2'? (compacting it every foot) Then sand for the last two feet? Job located in northeast U.S.A. Thanks
Will the driveway be asphalt or concrete? If asphalt you will need a dense grade base or crusher run type stone. This type of stone has a mixture of sizes plus fines that creates a very dense base for the asphalt when spread, watered and compacted. A typical residential street in my neck of the woods is 6:2:1, which means 6" of dense graded base, 2" of asphalt binder (a heavier aggregate asphalt) and 1" of wear course ( a finer graded aggregate asphalt). I wouldn't suggest that spec for a residential driveway unless you were expecting heavy traffic. A 6" dense grade with 2" of wear course or "baby binder" ( a slightly smaller aggregate binder course) should serve you well. If it's concrete then 3/4 or 1" stone will work just fine or the same dense grade base described above. I have always filled garages with #57 stone (our local screen size) which is 1/2" to 1" stone. This type of stone is "self compacting" in a residential application ( a low loading situation), meaning you can put into the hole and the stone is the right size that it interlocks together and doesn't settle. Now all my great advice has come from my life experience living in the Southern US, in which we don't see winters like you guys up North experience, so I may be totally off-base with my recommendations.:idea
1weare---For your driveway,the determination of what size stone to use depends on your sub base.If it's soft clay with any signs of water intrusion,definitely go larger 1.5'' to 2.5'' crushed stone,if it's tight and dry you can run a 3/4'' crushed stone.Whatever size you choose,I would recommend Item #4 on top,minimum 4'' thick.Also,if it isa soft sub base[or even if you are not sure] ,get yourself a roll of geotextile cloth to place between the sub base and your aggregate.Money VERY well spent. Your garage shouldn't need 6'' stone,that's way hard to work with and won't easily compact.I would just go with a nice clean bank run gravel[say largest stone of 3-4''] and compact no more than a foot lift at a time,less if you don't have a good serious tamper.I would finish grading off the top with the same product or go to a few inches again of Item #4 or 3/4'' crushed stone.Compaction is PARAMOUNT. Your top is what your bottom is.