View Full Version : Question about geogrid / perforated pipe

08-23-2006, 10:00 PM
I'm in my second year of business now, and I've done quite a few retaining walls, but I'm just starting my first wall which will require geogrid. The question I have is about which direction to roll out the geogrid behind the wall, as I've read opposite things. I've attached a picture below of the geogrid I'll be installing, and I'm hoping that someone can tell me if the side I labelled X should be running parallel or perpindicular to the wall face.


I also want to install perforated pipe as a drain which I've never had to do before, and I was just wondering where I can buy it from?? Or does anyone have any different suggestions on what to use as a drain?

Thanks in advance for any replies.

08-23-2006, 11:00 PM
I buy geo-grid in a large roll that is 15' wide on a large roll. Mine and there are different strengths has a arrow pointing out as you are looking at it on the roll. The arrow has to go back in the bank. Now i have just learned that there is a different kind that can go multiple ways, im not sure of it and i think someone else will comment on it. Mine has to go that way by the arrow due to that is how the tinsle strength is. It is very importanrt to get it right i knew a job in my area 2 years ago an inspecter on a state job asked if they gridded the whole wall like they just did. The contracter proudly said yes, he had to tear the whole wall apart 70' long 9 courses high because he ran the grid the wrong way.

08-24-2006, 12:02 AM
Go to your plumbing supply for perf pipe, tell them you want sewer/drain pipe, do not buy sched 40. Also be sure to wrap with fabric or use a sock to prevent clogging. Lastly if you daylight the drain instead of tying it into another drain or making a well close the pipe with a grate to prevent critters and give a finished look.

08-24-2006, 08:24 AM
Well your roll can only be rolled on one direction... your "Y" side. That would mean your "X" side would be attached to the wall. Pref pipe can be found at plumbing supplys, home depot, mason supplys etc. Make sure you use fabric and drainage stone as well when installing the pipe, and on large walls you are going to need outlets.

08-24-2006, 09:59 PM
Thanks for all the replies, I got the drain pipe put in today, and started on the first row of geogrid. I'm confident now that this wall will hold up forever, unlike the retaining wall I saw put in at the house next door which is already showing some problems.

08-24-2006, 10:28 PM
Make sure you run it min. 60% of height of wall. Since i dont know your surcharge 80% you will have a piece of mind, especially when a hard rain comes.