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Retaining Wall Installation - Best Practice

It's time for a post about retaining wall installation - best practice.  Retaining walls are something that home inspectors see frequently.  And just as frequently those walls have problems.

A recent post prompted many to think what is necessary to the proper installation of a retaining wall.  This is a very good question, and one deserving a response.

Retaining walls can be constructed of many things - metal, wood, brick and block, man-made blocks, and huge boulders and stone.  The idea is to retain the weight of the soil behind the wall, and divert water, and its pressure, away from a structure or pathway.

An engineer I have known and referred for many years is Ken Fraine, of Soil and Structure Consulting, Inc.  When asking him his thoughts regarding this post, he said,

"Nearly every failed retaining wall I’ve ever inspected failed due to an improper drainage system or a complete lack of one.  Note that [concrete] block walls should also have a waterproofing membrane placed on the backside to prevent deterioration of the mortar joints and the blocks themselves."

Drainage, therefore, is significant.  The the single-most reason walls will eventually fail.

Properly constructed, retaining walls are very complex.  Many things work together to insure their success, from retaining wall material, back fill, angle of the wall setback, stabilization into the rear structure and drainage, etc..

I have seen retaining walls made from the man-made blocks that are 30' high and more.  Of course, with that height, more drainage is necessary than the single collection pipe shown here.  Those blocks intersect, or have lips which rest on each other such that one cannot be moved as regards its neighboring blocks.

The collection pipe would be a 4" plastic tube with pre-drilled holes to collect and then divert water.  Of course it would be wrapped with a silt-filtering mesh and then protected with gravel (called Unit Core Fill/Drainage above).

Even with different wall materials, the components shown above would still apply.  And any wall constructed like the one in the diagram above would be

Best Practice

My recommendation:  just from a visual inspection or walk around, it might be difficult to determine if a retaining wall has all the components and structural capability of the diagram above.  But you can ask!  Find out who did the work, try to obtain any permits and receipts and investigate the company that put the wall in.  Doing all that will go a long way toward the peace of mind needed to know if a wall will last.



Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comment balloon 63 commentsJay Markanich • December 29 2011 06:40AM

Comments

Good morning, Jay. Yes, that is the textbook method of installation, but how often does that happen in reality?

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) almost 7 years ago

Jay, this is why you hire a professional with a solid track record for work like this. There was a house in Ireland at the bottom of a steep steep hill and the owner ( a landscaper of all things) removed all the natural plants and bushes in order to landscape it. Rained for about three days, unheard of in Ireland....and the hill moved into his living room!! Now he has a retaining wall. 

Posted by David O'Doherty, Clayton NC Homes, Raleigh, NC (Raleigh Realty Inc) almost 7 years ago

Don't know Michael!  I can tell you that when Ken puts together a wall it is like that.

David - experience and reputation are king, for sure!  Isn't it wonderful when the house becomes the retaining wall!  I guess the living room got soiled?

So to speak...

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Like so many things, there is a lot more to do it right than there appears...which is why we find so many things done wrong. Good information. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) almost 7 years ago

When reviewing a property condition disclosure, one should always consider a retaining wall as being part of the homes construction and request any documentation from the owner on the construction of the wall or, at a minimum, the name of the contractor who did it. For peace of mind purposes!

Posted by Randy Landis, Overseas Retirement Consultant (Retired in Samar) almost 7 years ago

Thanks. Good to know. Great job and good luck toy you and happy holidays 

Posted by JOSH EVANS *JoshEvansHomes 516-655-5000 (Village Properties of Mineola, LLC) almost 7 years ago

Good information and certainly a big deal here as many homes are built on mountain slopes. If corners are cut, it's going to be a disaster for the home owner sooner or later. Thanks for the details on how to ensure it's done correctly!

Posted by Charlie Dresen, Steamboat Springs, CO e-Pro (Steamboat Sotheby's International Realty) almost 7 years ago

Very good article. Geting it right the first time avoids the second experience.

Posted by Erv Fleishman, Luxury Prop Specialist Realty Associates (Realty Associates) almost 7 years ago

Jim - properly done, these walls are very complex!  Which is why so many fail.  Any aspect not done right leaves vulnerability.

Randy - in Virginia we have no disclosure laws, so asking for plans or receipts is essential.

Thanks Josh.  As always.

Charlie - these fail even with a slight slope, not to mention the mountains!  But we do have mountains here, so these walls come into play often.

Erv - the second experience is often the first experience for many buyers!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

I think they fail when the weekend warrior tries to install them...in fact I have my own weekend warrior...he is great with just about anything but the job of putting in a retaining wall should be left to professionals!

Posted by Linda Edelwich, Glasotnbury Office's #1 Top Producing Agent-not on (William Raveis Real Estate) almost 7 years ago

Great info Jay. Looks like I did everything right with the last wall I built except for the drainage pipe. The soil was very sandy, so hopefully I won't have any problems. I might have to plant a tree just to make sure. :)

Have an AWESOME day!

 

Posted by Michael S. Bolton, MN Appraiser (Michael S. Bolton,Inc.) almost 7 years ago

Jay, this is a job left for the pros. Building a good effective retaining is more complex than most people think.

Posted by Michael Setunsky, Your Commercial Real Estate Link to Northern VA almost 7 years ago

Great information! I made a couple of attempts to do retaining walls, but never did a great job, after reading the post, I can see why. I now leave it those that know more than I do.

Posted by Joe Petrowsky, Your Mortgage Consultant for Life (Mortgage Consultant, Right Trac Financial Group, Inc. NMLS # 2709) almost 7 years ago

You are right about the Linda.  Retaining walls are a big project!

Michael - make it a big one, and fast growing!

Mike S. - extremely complex.  And there are so many factors that go into it, the biggest factor being the terrain and how to deal with it.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Joe - we don't know what we don't know!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Great information as usual Jay.  Who knew that retaining walls were so complex?

Posted by Bill Rozek, NMLS #214260 (Embrace Home Loans, Inc.) almost 7 years ago

I studied landscaping in college and have a batchelors in landscape design. This is spot on and now as a realtor I am amazed even when "Professional Landscapers" skip steps and the key components. This is what make a great retaining wall that will stand the test of time and more importantly hydrostatic pressure in a heavy downpour!

Posted by Matthew Johnson (Keller Williams Premier Realty) almost 7 years ago

Trees and their roots along with other soil ingredients make perfect retaining walls says mother nature. I believe it is when we start to want to add something, the issues arise non-stop...good post

Posted by Richie Alan Naggar, agent & author (people first...then business Ran Right Realty ) almost 7 years ago

Very Interesting, Jay. It's amazing how water is both our friend and our enemy in different situations and controlling it is so important. As always, proper design and planning make a huge difference in durability.
Bruce

 

Posted by Bruce Kunz, REALTOR®, Brick & Howell NJ Homes for Sale (C21 Solid Gold Realty, Brick, NJ, 732-920-2100) almost 7 years ago

Very Bill.  And that lack of understanding is why so many fail.

Thanks Matthew.  It's good to know I get some things right!  Now, if you could tell my wife I am not a complete ditz in the kitchen?

Richie - most applications, particularly on new construction, require more than trees and roots.  But they are very effective when left in place and planted properly.  Look at the hills along the interstates.

Bruce - water is THE killer of houses when not controlled, inside and out.

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Jay - Great information for those who are actually concerned about proper installation. Those who ignore the "rules" usually suffer the consequences.

Posted by John Mulkey, Housing Guru (TheHousingGuru.com) almost 7 years ago

I was just contemplating buying a home with a retaining wall but I am kind of wary! Between having to mow over top of it and having to worry about the thing needing replaced some day I am just not sure if it is worth it! There are a lot of fish in the sea! Happy New Year Jay!

Posted by Rosalie Evans, The Evans Group, Sioux Falls, SD Homes For Sale (Meritus Group Real Estate) almost 7 years ago

Great information Jay, Retaining walls are the type of things you do not pay attention to, unless something goes wrong.

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) almost 7 years ago

John - thanks, as always.  Retaining walls are one place you don't want to skimp on the family recipe.

Rosalie - check it out carefully!  And thanks, with the same wishes back at you.

Chris - over time we would like to know they are there, but not having to bring them up in conversation!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Jay: Thanks for the post. My first thought is to say the process is clear as mud, but I think its a little better than that. I will study this diagram! 

Posted by Anne M. Costello (Weidel Realtors) almost 7 years ago
As always, well done Jay! Too many retaining walls just seem to be put up with no drainage.
Posted by David Gibson CNE, 719-304-4684 ~ Colorado Springs Relocation, Relocation, Luxury & Lifestyle residential (Colorado Real Estate Advisers LLC ) almost 7 years ago

Jay, yet another great post, complete with illustrations and explanations.

Sadly, most homeowners don't find out construction rules weren't followed until after the fact. Like the guy who wound up with a hill in his house.

Posted by Jon Quist, Tucson's BUYERS ONLY Realtor since 1996 (REALTY EXECUTIVES TUCSON ELITE) almost 7 years ago

Jay -- what a great diagram to cement in the points you made regarding best practice on building retaining wall.  Sometimes around here they skip a few steps - with the clay and rock (though I would think it would be more important.)

Posted by Steven Cook (No Longer Processing Mortgages.) almost 7 years ago

Great information.  I know that drainage is so important in a retaining wall - even if they just have a few holes drilled, it's better than nothing.

Posted by Joy Daniels (Joy Daniels Real Estate Group, Ltd.) almost 7 years ago

Anne - you are welcome!  Hopefully now, when you put in your first wall, you will know what to look for!

David - that seems to be the most common problem.

Thanks Jon.  My legal name is Jon, by the way.  After the fact is the worst time to find out about retaining walls.

Steven - it is easy to see when steps have been skipped!

Thanks Joy.  The best drainage is from behind, with the water diverted into it.  But holes work too, just not as well.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

When we were looking for our last house we really liked one in particular, but the retaining wall in the back scared us away. It was literally made from old tires and other assorted junk. We didn't even get far enough to have it inspected... we just didn't want to deal with it and moved on. It's so important they are built right.

Gretchen

Posted by Mel Ahrens, MBA, Kelly Right Real Estate, Customized Choices for your Real Estate Needs (Kelly Right Real Estate) almost 7 years ago

Gretchen - that sounds like a pretty circumspect decision and you may have avoided a load of mess!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

I am and have for years been leery of retaining walls.  I've seen so many of them leaning, buckled, bulging, crumbling, depending on the materials used. 

Most, however, are outside the range of home inspection defect repairs.  Often buyers must either make repair a condition of the contract or take it as is. 

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) almost 7 years ago

I agree with the Lenn, but still, on a home inspection, I am going to mention what I see.  It is hard to tell what is underground and whether they have been constructed properly.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Nice diagram.  If I ever build a retaining, that's what I'll aim for.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

Jay:

I too am leery of retaining walls.  If a client considered buying a home with a retaining wall I would strongly recommend inspections by experts who could evaluate the wall's integrity.

Posted by Evelyn Kennedy, Alameda, Real Estate, Alameda, CA (Alain Pinel Realtors) almost 7 years ago

I can read the diagram. I still can’t build a retaining wall. That is what contactors are for. Good information, Jay.

Posted by John Juarez, ePRO, SRES, GRI, PMN (The Medford Real Estate Team) almost 7 years ago

Bill, I've seen a lot of retaining walls that looked like RETARDED walls!  Here in Hawaii we see a huge amount of moss rock walls built by people from the South Pacific Islands and of course, they are without license and without building permits.  Then the owner expects us to iron things out years later.

Posted by Bruce Hicks, Your Lifetime Friend/Helper! (Best Homes Hawaii) almost 7 years ago

That's a lot of work Reubs!  Don't forget the geosynthetic reinforcement (plastic dead men, but engineers cannot be so clear).

Evelyn - the older I get the less my X-ray vision works, and I bet it is the same with engineers!

John - we all have our role.  "A man's gotta know his limitations..."  I think a prophet said that.  Oh yeah, the Prophet Dirty Harry.

Bruce - I see a lot of retaining walls here made with very large boulders.  And they work!  Mostly those are on public works properties, like highways, but I have seen a few in very large private properties.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

jAY~Of course I am bookmarking this, so that in the future I will really look like an "expert" if this comes up...which it has in the past and then I won't have to try to recall all of the dos and don'ts of a retaining wall (to be built or if existing), I will simply forward this on!

Congratulations of your feature. Oh, and it's all about Best Practices and a Happy New Year.

Posted by Gayle Rich-Boxman Fishhawk Lake Real Estate, "Your Local Expert!" 503-755-2905 (John L Scott Market Center) almost 7 years ago

Thank you Gayle, for all the compliments.  Great nose by the way!  And all the happy backatcha!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Very informative. I guess I, as a lot of others, tended to over simplify retaining walls. When you look at one it appears as simple as dirt. As you point out it's not so much retaining soil but disposing of water so hydrostatic pressure is not allowed to build up behind the wall.

Posted by Marshall Brown, BSEE, CHI (Mid America Inspection Services, LLC) almost 7 years ago

Great Marshall.  It is the water pressure that kills the wall, or deteriorates it from behind!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Hi Jay, thanks for your post.  They are always so educational.

Have a Happy and Prosperous New Year!

Posted by Bob Miller, The Ocala Dream Team (Keller Williams Cornerstone Realty) almost 7 years ago

Thanks Bob, and the same backatcha!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Hi Jay!  I have to say, I have yet to see a retaining wall on an inspection that isn't showing signs of failure.  I even saw one made of those massive concrete blocks that have to be set in place by a crane (so you know it wasn't DYI), and it was one of the worst.  Unfortunately, the need for drainage seems to be often misunderstood.

Posted by Julie Babcock -Nook & Cranny Home Inspections (Nook & Cranny Home Inspections Tonawanda, NY) almost 7 years ago

You are such a thorough home inspector, which makes you very good at what you do! You always have some new information I didn't know and this was one of them! Thanks for the info!

Posted by Sylvie Stuart, Home Buying, Home Selling and Investment - Flagsta (Realty One Group Mountain Desert 928-600-2765) almost 7 years ago

I think you hit on it Julie.  It was probably the lack o' drainage behind that compromised even the biggie retaining wall.

Sylvie - you are very welcome.  Have a happy happy.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

What one has to marvel is in ancient times, building and wall retention that still stands today. This in contrast to the attempts that you come across in your inspections.

Posted by Winston Heverly, GRI, ABR, SFR, CDPE, CIAS, PA (Winston Realty, Inc.) almost 7 years ago

Great article.  I did install my own retaining walls 10+ years ago.  Followed all the instructions carefully, except I cut the embedment depth on one side of the house.  It started raining and the whole wall next to the house slid forward a bit.  Water followed it to the foundation wall and followed it around and into the basement :(.  Pulled out the whole thing, dug out the trench another 6" relaid the foundation and reset the whole wall.  Been solid as a rock for 10 years now.  You're certainly right that you can't take short cuts, but a home owner who can and will follow directions can do it right.  Contractors can also be templted to take shortcuts.  It's mostly just hard physical labor.

2 level retaining wall

Posted by Alan Mackenthun (Bridge Realty) almost 7 years ago

Not many retaining walls here in Northern Florida. One less inspection issue to deal with in terms of possible hidden damage. Happy New Year!

Posted by Bill Reddington, Destin Florida Real Estate (Re/max Southern Realty) almost 7 years ago

This is an excellent post.  Thanks for the information.  This is good consumer information that I like to share with clients.

Posted by Gene Riemenschneider, Turning Houses into Homes (Home Point Real Estate) almost 7 years ago

Winston - there is a lot of ancient stuff, on different continents, that we all need to wonder about!  They had some great engineers!

Alan - you are right about the no short cut thing.  And you are right, drainage is everything.  Obviously you did a great job!

Thanks Bill.  What, things are pretty flat there?

Gene - thank you!  We try to be very instructive!  I am glad it is a sharable post.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Thanks for all that valuable info. Never realised there was so much behind the construction and detail of a retaining wall that needs to be fulfilled in order to last.

Posted by Jennifer Chiongbian, Real Estate Broker - NYC (Specializing in all types of Manhattan apts & townhouses) almost 7 years ago

It's all true Jennifer, and if steps are skipped they don't last!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Jay,

Hydrostatic pressure is a remarkable force. Dewatering is vital to hillside stablity. Many landslides are the product of excessive water pressure. Congratulations on your feature. SC

Posted by Steve, Joel & Steve A. Chain (Chain Real Estate Investments & Mortgage, Steve & Joel Chain) almost 7 years ago

Thanks S&J!  I see evidence world wide that water is a remarkable force, for sure.  Have a great new year.

 

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

My neighbor decided to excavate the slope between our yards, leaving an 8 foot vertical dirt wall that he thought would be held back by simply installing those Pavestone overlapping blocks on a dirt base.  No drainage, no footing and definately over the height limit for this type of block. Fortunately, the city stopped the project before the three adjoining neibor's backyards slid into his yard in a massive land slide!  Additionally, there were no permits with the city!

The city made him submit plans created by an engineer requiring the installation of a concrete block wall (with the cells filled with concrete) built on a footing with correct drainage...the proper way to do it!

This type of work should not be left to day laborers with no experience in the correct installation of retaining walls.

Posted by John Alesi, (Orange County California Real Estate) (Century 21 Award) almost 7 years ago

John - that sounds like a disaster planned from the start!  Good thing the city got involved.  And you are right, this kind of thing is no day laborer undertaking!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Jay, Thanks for the great illustration showing how a retaining wall is supposed to be done. Maybe if homeowners can see this, they'll realize this isn't a simple weekend project and call for help.

Posted by Tina Gleisner, Home Tips for Women (Home Tips for Women) over 6 years ago

Tina - there are a couple of "retaining walls" I can see from my house that could have used a diagram!  And thanks!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Retaining walls built to code around here are very robust. I built one I called "The Iraqi Tank Trap". It was so much over-kill.

Posted by Wayne B. Pruner, Tigard Oregon Homes for Sale, Realtor, GRI (Oregon First) about 6 years ago

Sounds very cool Wayne!  Would love to see a photo!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 6 years ago

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