Question
Hey Sean,

I checked out the preformed retainer wall cement blocks at Home Depot.  Good news!  Only $1.54 each!

Are these blocks suppose to be laid directly on the dirt, or do i have to lay some gravel or sand first?

Looking forward to hearing from you,
Wayne
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The text above is a follow-up to ...

-----Question-----
Hey Sean,

I'm in the process of trying to landscape my backyard.  I have alot of "vision" but no credentials to back my vision.  If i had money, i'd just hire someone. Although i think i'd get much more satisfaction out of making things "nice" myself.

My biggest obstacle at the moment is trying to figure out how to get rid of my neighbors VINES!  I think they originally planted these vines so they wouldn't have to look at my backyard which is always at the dirt stage....until winter comes and i get six foot weeds by summer.  (Northern California)

But anyway, these vines grow up from their side, over the chain link fence (which also has to go!) and then proceed across my yard.  The last ones i chopped were 10 feet across my yard.

They're not interested in pulling up there vines, and i had a big argument with them last week.  Basically saying i was sick of cleaning up their vines.

I was thinking about building some kind of wall with a solid lid over the top so that the vines had nowhere to travel.  Not sure if that would work though.

Any idea?

Looking forward to hearing from you,
Wayne
-----Answer-----
Well without knowing what type of vine it is its hard to give you an exact solution but off hand I'd say you have two choices that don't involve a lawsuit or fight with your neighbor.
Build a wall and hopefully the vine is not a "suckering" type and that will stop it. Or two, build a solid fence with no gaps. Regardless though, even if its not a suckering vine, if it is a vigorous grower it may still pile up on top of itself and climb your wall or fence so regular bi-annual or even more often maintenance may be necessary.
I am Sorry, but unless you are willing spray 'round-up' or some form brush killer which will or might kill the root all the way back in your neighbor's yard...you are pretty much stuck with an ongoing maintenance issue.
Also check local ordinances and see if the vine is a listed nuisance or if their are laws pertaining to requirements on your neighbor to control it.

Answer
Regarding installation of interlocking concrete block walls, the best thing to do is check with the manufacturer for their installation recommendations. Home Depot may have a brochure in the area where they are sold or you can google the company that manufactures them and see if they have instructions on their web site.

However, the basic practice for these type of walls typically involves a trench to be excavated below the local frost depth and filled with crushed gravel. The gravel is leveled and compacted with a vibratory plate compactor, (you can rent and haul in small pick up). After that each course of block is laid using a level and a string to ensure it is straight and even. After each course is laid it is back filled with gravel and soil and this soil is compacted. If the wall is taller than 2 or 3 feet you often are required to install a layer of "goegrid" reinforcing mesh. This is a roll of coated geotextile (strings) that is pinched between to layers of block and extends back into the soil for several feet (length of extension is dependant on height of the wall). In some designs a french drain is put behind the wall to capture the water moving from up slope into the gravel behind the wall. The french drain is then directed underground to a lower are of your yard where it can drain out onto the yard or into a storm sewer.

In general, I do not recommend using the small blocks that are typically less than 40lbs each. Those little blocks do not hold well and are really only suited for decorative rings around plants. My personal opinion is that these little blocks are not well suited for long term use or aesthetics. You may note if you drive through nicer neighborhoods you will not see these blocks being used. If you want a solid wall that will stand the test of time and looks substantial use only the larger ones that range from 40 to 90lbs each. and these will typically cost you at least $4.00 each if not more.

Anchor Highland Stone, Anchor Diamond Stone, Allen Block, Keystone, etc. all make good products, some of which Home Depot carries. Google them for more info. Or just cut and paste this into your search bar:  http://www.google.com/search?hl=en&q=interlocking+concrete+block

Good Luck


Sean J Murphy, LA,ISA, LEED AP
Please check out my blogs and articles on landscape topics like this on my websites.
http://www.seanjmurphy.com
http://amenityarchitects.com