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How deep is your base?
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Posted by well_drained z6a MA (My Page) on Tue, Jul 27, 04 at 13:49
| I'm trying to figure out how far down to dig for a base for a rock path and patio. I live in eastern Mass. and I'm concerned about frost heaves, drainage and longevity.
Between the Gardenweb and various other websites, books and magazines, I've heard everything from three inches to 18 inches deep. You can't push a shovel two inches into the ground in my New England yard without hitting a rock or a root, so I'm trying to find the lowest base depth that will still meet my goals.
The sources also differ about the materials to use for the base. Several recommend a layer of gravel or crushed stone on the bottom, covered by a layer of sand or fines. But they differ about how thick each layer should be.
Any assistance appreciated,
wd
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Follow-Up Postings:
RE: How deep is your base?
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| Frost heaves and drainage are closely related. Basically, you need to get rid of anything that doesn't compact (topsoil) and replace it with material that compacts into a porous but very solid mass. For a patio or walk, the standard is at least 6" of base (gravel, crushed stone) plus a couple inches of sand. If you are placing interlocking pavers, you can compact the sand, lay the pavers and recompact. If you are laying irregular bluestone or other flagging, you need to leave some uncompacted sand to level the stones. Roots are bad news. They will heave any pavement if allowed to remain, even if they start deeper than the base. They are the reason many good contractors will go down at least a foot with compacted base, as it will eliminate all but the deepest, and they might not show up for years. Don't leave any rocks in the base - they will telegraph through to the top. |
RE: How deep is your base?
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I am working on a stone retaining wall apx. 18-20 inches tall with various rock types. the base is shallow and i think adequate for the height but only now have roots concerned me. the wall is at the sidewalk in front of the house with room for the roots to grow under the walk. Do i
cut the tree roots off and risk tree damage? what to do??? Also, mortar for the odd sized and shaped rocks is a problem to apply. Any tools info. and or suggestions would be greatly appreciated. |
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