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RE: Dry Stack Rock Wall

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I meant to reply earlier but it looks like problem solved.  FWIW, I used to design rockeries in Seattle about 15 years ago.  At that time, it was required to "chink" the rocks with angular crushed rock, 3" to 8" in least dimension.  The Seattle detail that you linked showed drain rock as small as 3/8" behind the rockery with no filter fabric to prevent the drain rock from "running" through spaces between the rocks.  I worked with a rockery contractor that really took pride in his work and placed each rock "just-so" and his rockeries never had any problems.  This work can't be done cheaply.
Bob G.
-----Original Message-----
From: Joe Grill [mailto:jgrill(--nospam--at)]
Sent: Tuesday, September 21, 2004 2:21 PM
To: seaint(--nospam--at)
Subject: RE: Dry Stack Rock Wall



I may not have to do this now.  The architect and contractor are in a huge hurry.  I ran across a web page by the Seattle Department of Planning for a prescriptive design for "Rockeries".  A 6' tall wall would require the lower 3 feet to be " 4 man-rocks" or larger boulders.  They define a 4 man-rock as being 3000# to 4000# with a volume between 18.4 to 24.5 cubic feet.  I started to try to write a spreadsheet to do the design when the architect called.  When I told him things may be in this range or larger for the 10' wall that he was proposing he said we will probably go with a cantilevered wall probably CMU.  I then talked to another (the third geotech.) that I know who said again that there wasn't really any design criteria for these since they were...lots of bad expletives...walls to do and were best designed by the competition.  He said there are lots of failures and require a lot of expertise in building etc. etc.  His comment was the design is one thing but the devil is in the details.  He doesn't do them any more.


I would, however, like to see some design criteria if anyone should run across it.  If I find any I will try to remember to share it with you.


I think the link to the Seattle publication is as follows:


By the way, I would also like to thank Jake Watson for his help with my question in this matter.  He is the one who let me know these are called "rockeries" which gave me a little more to google with.  Thanks Jake!


Joe Grill


-----Original Message-----
From: Jnapd(--nospam--at) [mailto:Jnapd(--nospam--at)]
Sent: Tuesday, September 21, 2004 1:43 PM
To: seaint(--nospam--at)
Subject: Re: Dry Stack Rock Wall




What are the sizes of the rock you have to use ??


I am in the process of designing similar walls from 4-8' tall. I will be using a min 2' dia. rock at the base of a 4' wall and 6' dia rock at the base of a 8' high wall.  Rock densities shall be over 165 pcf.  We have VW size boulders across the site. The wall will be battered at 1:2 into the bank. We ask the contractor to provide a contact surface between the boulders that leans into the bank at 30 degrees.


Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA

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