7 Commonly Overlooked Retaining Wall Install Mistakes that Lead to Failure

what's happening hard skaters today i want to get into seven commonly overlooked retaining wall installation mistakes that lead to failure let's get into this now previously we did this with interlocking concrete pavement installation mistakes that go commonly overlooked and we're going to draw on that and expand a little bit more because there are some similarities between these two installations of interlocking concrete pavement and retaining wall structures and most importantly this has to do with the base and we talked about excavation having the right aggregate and the right base depth but also with retaining walls we need to make sure that we have an extension beyond the toe of the wall and in behind the wall you should have a minimum base extension of six inches in front of the wall as well as a minimum of 12 inches behind the wall from the face of the wall to the back of the drainage area should actually be 24 inches so in some cases you actually may be looking at more than those 12 inches in behind the wall for that base this allows for more than enough room for that wall unit to sit without being displaced over time we also talked about compaction and compaction is just as important with a retaining wall structure both with the base as well as the backfill area and because a lot of these different commonly overlooked mistakes with retaining wall structures mesh into one another we'll be covering this many many times but compaction is one thing that is incredibly important with the base preparation all the way up the backfilled area ensure that you have proper compaction equipment for your project this generally means a reversible plate compactor that has enough force to be able to work in lifts depending on the force that that compactor is able to apply and a rule of thumb is one thousand pounds of force for every one inch of material it's compacting poor compaction over time will lead to unevenness in the courses causing your wall to look like waves from course to course however this could be done just from the installation not being proper with ensuring that your initial layer your initial course is level and each subsequent course is also level continuing along with the backfilled material in behind a wall this actually is the cause of many failures that i see and this is usually because the wall is leaning forward and this is because the water the hydrostatic pressure in behind that wall is causing pressure to build up and push that wall forward because there's no drainage material typical drainage material in behind the wall is a three-quarter clear stone angular crush and this has minimal fines in it for water to move through the system and down and into a drainage pipe which we'll be getting into very shortly here but that backfilled material is incredibly important and we talked about that minimum 12 inches in behind the wall for the base that should also carry up the wall for that drainage material and maybe even more depending on engineered drawings improper drainage in behind the wall can cause the wall to push forward but also it could leave efflorescence deposits on the surface on the face of the wall and this looks incredibly unsightly and it needs to be acid wash to be cleaned off this is because efflorescence is caused by moisture because the presence of moisture in behind that wall that moisture will wick its way through the face of the wall bringing with it and dissolving mineral deposits on the face of the wall continuing along with that backfill we're going to talk about the drainage pipe as well because this is commonly overlooked and that drainage pipe should be perforated for water that builds up in the system to be captured by the drainage pipe and moved out of the system or sometimes even through the face of that retaining wall if you're using three-quarter inch angular crushed stone for the entire base as well as the backfill material that drainage pipe should actually be placed lower in that system however if you're using a three-quarter inch minus for the base material and a gravel something like that that is three-quarter inch angular crush down defines in it and you're gonna be using a three-quarter inch clear stone for the backfilled material you'll want some sort of non-woven geotextile to separate those two and then that drainage pipe can be placed in that backfilled material as opposed to lower in the system into the base embedment is another crucial part of this whole system and you need to have a minimum of six inches embedded below the final grade and this could increase depending on a lot of different factors including the height the slope beyond the wall and the surcharge that is actually placed on top of the wall we actually don't even have an embedded layer underneath this so this you can see actually the base the a gravel here washing out through this corner we've got our embedded course there and i'd be interested to know if there's another embedded chorus below this because with this high of a wall i would hope there would be but here in this corner in such a crucial area we've got no embedment and we're getting that wash out of the base which will lead to eventual failure of at least this corner if not further up the retaining wall it's always important that if you're going over a certain height depending on your local codes that you do have an engineer create this drawing for you that you can then follow which brings us to staggering the wall units many times i do see a diy project where wall units are just stacked in one single line the stagger is what gives the retaining wall strength acts as a single unit a single mass withstanding the surcharge that is placed on that wall without that stagger you're missing a lot of strength from withholding that surcharge that's placed on the wall segmental retaining walls are designed to have that stagger a minimum of a third of a unit from one to the next and then finally height and height encompasses a lot of different aspects the height of your wall depends if you're gonna need some engineered drawings or if you can follow the manufacturer's specifications for that specific product it also depends what kind of products you can actually use to build that wall because not every product should be built for a retaining wall retaining wall products without mechanical clips or without some sort of clipping system built into the unit should only be built to a certain height which is usually not that high as your height increases so too should the weight of each segmental retaining wall unit in that system a setback can be placed on that wall or a batter which is where each unit from one course to the next is set back at a specified angle typically already built into the segmental retaining wall unit this helps withstand the force that is applied from behind the wall that surcharge additionally a geogrid can be used to also stabilize the material in that backfill area preventing any further pressure placed on the back of that retaining wall or that surcharge load the construction of retaining walls get really technical and these seven things should not go overlooked and many many others but these are the most common things that i do see in a retaining wall construction that definitely doesn't mean that's the only things and if you have specified engineered drawings for your retaining wall those do need to be followed luckily manufacturers typically have some sort of specified drawings and the heights to which their wall units can actually be built to however with larger static and dynamic loads that are placed on the wall or with steeper slopes beyond the wall this may require engineered drawings to be able to construct that wall it's better to be safe than sorry especially with retaining wall structures and if you want to learn more about retaining wall construction we do have a members only platform for how to hardscape with a two-hour course in there on retaining wall construction that goes through everything in depth that we've already talked about in this video as well as many other aspects from start to finish for retaining wall build if this video has helped you in any way please give it a like comment below any questions that you have and subscribe to this youtube channel for more hearts keeping content thank you so much for watching

Channel: I Am a Hardscaper

Views: 74,790

Keywords: hardscape, hardscapes, hardscaping, hardscaper, hardscapers, installation, paver, pavers, paving stones, paving stone, contractor, contractors

Id: HD5BwGr1jpw

Length: 8min 9sec (489 seconds)

Published: Fri Jul 01 2022