How to Rebuild a Concrete Block Retaining Wall | Ask This Old House

Ask This Old House mason Mark McCullough rebuilds a retaining wall that was stacked with the wrong material.
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Time: 2-3 days
Cost: $4000
Skill Level: Moderate
Tools List for Rebuilding a Concrete Block Retaining Wall:
Shovels [amzn.to/2mQYAwP]
Wheelbarrow [amzn.to/2mv6dco]
Tamper [amzn.to/2mo5iKB]
Rubber mallet [amzn.to/2mwVVrT]
Level [amzn.to/2mZkdv9]
Wet saw [amzn.to/2lhfVPm]
Shopping List:
Tarp [amzn.to/2lhb4O6]
Gravel [amzn.to/2mQJw2e]
Concrete blocks [amzn.to/2mXvzzM]
Channel connectors
Fabric liner [amzn.to/2ls9sky]
Perforated plastic pipe [amzn.to/2lik1Xt]
Construction adhesive [amzn.to/2mZ2rbn]
Steps:
1. Remove any plants lining the retaining wall with a shovel. Dig deep to give the plants a strong root ball.
2. Transfer plants temporarily to a tarp for safekeeping.
3. Remove the pieces of the old wall.
4. Dig a few inches back and deep along the location of the old wall.
5. Lay a thick base of gravel along the trench. Pack it down tight with a tamper.
6. Lay the first course of blocks about halfway deep in the trench. Lay one block every six feet or so along the length of the wall, level those to one another, and then fill in the rest of the wall. Use the rubber mallet to secure the blocks in place.
7. Lay a fabric liner along the back and base of the wall.
8. Backfill behind the first course with more gravel.
9. Lay the next course of blocks. Line up the channels using the channel connectors. Be sure to not overlap face joints.
10. Lay the perforated plastic pipe behind the wall and backfill with gravel.
11. Install the next course of blocks the same as the second. Backfill with gravel. Repeat until the wall is at the desired height. Some blocks may need to be cut with a wet saw to ensure an even fit on each course.
12. To secure the top cap for the blocks, add construction adhesive to the top course of blocks. Then add the cap pieces. Even it out with the rubber mallet.
13. Return any plants back to the wall if needed.
Resources:
Mark used Mini Creta 6” landscape blocks in the color sandlewood, manufactured by Techo Bloc (www.techo-bloc.com/en/).
To join the top cap to the blocks, he used Gorilla Construction Adhesive, manufactured by Gorilla Glue [amzn.to/2mvcUew] (www.gorillatough.com/).
Everything else he used, including shovels, landscape fabric, and gravel can be found at home centers, landscape and masonry supply stores.
Expert assistance for this project was provided by MJM Masonry (www.mjmmasonry.com/).
About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers-and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.
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How to Rebuild a Concrete Block Retaining Wall | Ask This Old House
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[@analarson2920]

Awesome job and I love the the new stone with the double row of locks, I did not notice the showing of how to connect more drainage pipe and the end caps which are important to keep things from accumulating over time. Keep sharing, may everyone prosper from this kind of stuff, I know it has helped our family over the years, a great blessing.

[@pamelaatkinson5710]

Didn't realize how much went into putting up a retaining wall! Such a physical job! This looks fantastic!

[@garciavashchino1]

The retaining wall came out so classy looking, very nice.

[@construction-productscemen4935]

The finished product looks fabulous.

[@MSI2k]

Man, the finished product looks fabulous.

This is the quality that I like to do for my landdscaping business startup. I am still learning where I am at in Seattle.

[@LongHuII]

I bet there's a lot of business for walls there.

[@PJJ196]

Wow huge improvement .. looks amazing.. great work ❤❤

[@johnjerrehian4642]

New wall is a huge improvement! Nice job!

[@mversantvoort]

The new wall looks great!

[@petecockett8291]

I live these DIY videos by these guys....great information...

[@WeykampLandscape]

Those stones are from TechoBloc - MiniCreta 6" - Champlain Grey. With Escala Coping They did a decent job installing. If anything I would recommend excavating more dirt from behind the wall to allow for more gravel. Approximately 1'-2' would help the wall drain better and last longer. The most important steps with retaining walls are making sure the base and back of the wall have sufficient gravel and cloth to reduce sediment from clogging the gravel.

[@n121pp67]

Jake Weykamp Awesome thank you so much for posting the details!!!

[@finkthreely7089]

What is the tallest height this method should be used to build?

[@firesurfer]

@@finkthreely7089 3 feet.

[@frankmiller95]

Rhetorical question: Why are there so many people posting criticism of the engineering on this when the guy doing it is a pro, and, unless we missed it, none of them have engineering or landscaping degrees that indicate they know better? This is no different than some bullshitter from Queens, who's never served a day in the military, saying he knows better than the generals. Really, WTF?

[@amberts180]

I wish I could give this more likes. Thanks for sharing

[@Astinsan]

The rock is a foot for the wall. Gravel or crushed rock tamped down is like concrete. It gets more stable the more in compacts down. That’s why they call it a base rock material at the home improvement store.

[@plummetplum]

Looks good. How do they exit the drain pipe neatly?

[@NEOhioTrainFan]

Nice catchy music especially at 2:48

[@thisoldhouse]

Thanks! Our composer is Jordan Critz

[@kalijasin]

That’s significantly better. Wow!!

[@1sttigertiger426]

Where did the perforated drain end?

[@microphonixvirtualstudio1634]

You can also use 1' X 2' blocks of concrete 2000 lbs each to build a retaining wall. It requires no mortar and no back fill. It need not be anchored to anything.

[@lucky1206]

I like watching these videos with the 'lets get to work' songs ha ha...pretty good job

[@RodneyIbarra]

Where is it draining to?

[@dctineffect]

Excellent video- helped us envision what it will take for our wall. But I have to say "Preforated"? maybe "perforated". lol.

[@buckbuck9225]

Nice job.for this old house..

[@redracer1999]

wow, looks great!

[@emmett3067]

Awesome video. Well explained and looks like a quality job.

[@smudge6831]

Great Scott!

[@BrewPub]

Where is the drainage pipe dumping the water to? I don't see any veep-holes between the concrete blocks of the 1st course.

[@npsit1]

Look at all that nice soft dirt...

[@gpslightlock1422]

That is really nice.

[@beauch1119]

For a retaining wall that isn’t on a hill, is it necessary to put in that perforated tubing? We want to replace the old large rocks that act as a retaining wall in front of our house that edges up to the sidewalk. It’s not downhill. Just wondering if that would be necessary?

[@watchmenpropertyinspection3469]

perfect. built to last

[@andrewmiguel8951]

Its look good but theres 2 problem that i didnt see. 1 where did he connect the pipe . 2 the gravel need to be open the water can run tru the gravel.

[@EverydayworkAli]

That was quick.

[@magreger]

What a difference when things are done correctly

[@paulprice9397]

How far below my level line should I allow for two rows of 8” block 2 rows high. I’m at 1” 1/16 now

[@japan-e9j]

Excellent job beautiful

[@0011clem]

good job.

[@kevinleven7482]

4:45 her eyes LOL

[@P2055516]

Crystal Meth ?

[@OUigot]

She's creepy, with a manly stance and looks like she never laughed a day in her life

[@juliof970]

Who provides the soundtrack to all the montages?

[@heroknaderi]

Good job

[@ukrakmeup13]

Does anyone have a link to those those blocks used? Been looking for big ones like that...

[@Flaaendue]

what kind of blocks are these? I am trouble finding on my local box store website

[@jamesw4912]

What happened to Roger he's supposed to explain it to us

[@Scimu]

Tom took him to the hardware store to source more caulking

[@jamesw4912]

funny

[@maykerlara1]

james w cccCCcc. B.B. bbbbbbbbbbbbbbbbbbbbb My. 3AWZ

[@joshbrennan8774]

This wall didn't need any mortaaaa so Roger said no dice

[@rbeck3200tb40]

Hes in someone elses yaaaaaaad planting bushes three and a quaaaata inches apaaaaart

[@photondebuger45]

Ahh memories I would watch this like in the morning when I was like 10 and just putting this out there I would make me sad if anything happened to the original cast like Silva and the other guys. I've watched them since I was young

[@C-Mah]

What do you do with the top of the fabric before laying the capstone? Just fold it over or leave it pulled back?

[@firesurfer]

Cut it 3'' below the top of the dirt.

[@Britineeng]

Do you start the wall at the highest or lowest point?

[@jeffreyrivers1983]

Roots grow!

[@bluelambo31]

Great video

[@Mixwell1983]

Was hoping to see Roger on this one.

[@tomn.9879]

And thank you, this is a great video! Are there any rules/guidelines that a homeowner should follow to help choose the best material for a retaining wall? Brick, boulders, wood, etc.

[@AStanton1966]

Pressure-treated timbers with deadmen are the easiest and cheapest to use in retaining walls. However, the chemical starts to leave the timbers after about 10 years. And the carpenter ants love to move in, chew on the wet wood, and expand their colony to your house. I have an exterminator now treat my timber wall annually and it still standing--holding back 4-feet of earth--going on 22 years. When constructing a wall, you have to look at design and height. Any wall approaching 3 feet or higher is usually called an engineered wall and will fall over if you don't know what you are doing. Stone or block is the way to go if done right. However, it will be the most expensive.

[@steelyspielbergo]

@@AStanton1966 I'm watching this video because I'm about to replace my wood wall with something else. Versa-lok probably. Anyway, it's 6 years old and falling apart because of ants. I didn't know about this problem and didn't do anything to prevent it. Live and learn.

[@AStanton1966]

@@steelyspielbergo I learned from my elderly neighbor. He had a wooden retaining wall up against his house which gave the carpenter ants a highway right into his house and wooden structure. I would never recommend butting a wooden wall against a house or building made out of wood.

[@steelyspielbergo]

@@AStanton1966 I worry about that too. My wall is against a basement wall. It's brick so I can't tell if anything got in there. I sprayed a bunch of poison into the weep-holes hoping that might work.

[@AStanton1966]

@@steelyspielbergo If you don't see any ants, you are probably good. You can always call a professional and have him give the area a quick spray. Just don't get involved with any of those big named-corporate chain exterminators.

[@emersona9]

That drainage zone should be at a minimum 12 inches behind the wall I only saw maybe 4-6. The two most important aspects of a retaining wall is the base and the drainage. They are the difference between a good construction and one that fails in 2-3 years

[@AStanton1966]

If that wall was over 3 feet high, I would agree. However, that wall is hardy holding back anything--so no biggie.

[@donaldlee6760]

@@AStanton1966 - 12 inches is a good rule to follow, but yeah, the wall is so short and hardly holding anything back so I agree it's a "no biggie" too.

[@georgefeliz7875]

Hey I like to know where can I buy does bloks? Thanks 👍

[@leetomlee7265]

Who is the manufacturer of this concrete blocks? I would like to build one myself. If I have a slope at the highest point (from bottom to top)about 4 feet and from this 4 feet high slope extending 40 feet to the other end (right to left) with the height of about one feet, would this concrete blocks on the high end side strong enough to support the dirt?

[@TrainFlood]

Wow that’s a hell of a lot of work.

[@kathiecannon6927]

curious what is on either end of the drain tube that was inserted. Open at either end (allowing dirt to fill the tube)? Closed at either end? Hummmm

[@rbeck3200tb40]

its probably closed on the end by the house and open sticking out a little towards the end of the driveway towards the road. Watch a guys youtube channel called "Apple Drains" He is the best drainage person out there with decades of experience

[@kirkswenson7566]

rbeck3200tb40 Chuck from Apple drains is awesome but rarely shows a retaining wall.

[@chopperboi89]

What did they do about that big piece of rock? There seemed to be a large rock when they were putting in the gravel (3:00)

[@firesurfer]

Leave it alone, just work around it.

[@68camarorsss33]

I come to the ATOH comment section for all the armchair contractor “you should of done it like this” comments

[@seemapagarkar9]

68CamaroRS/SS qqqqq

[@mtadams2009]

Same here.

[@joncrosby8988]

@@LuggageStardate except at 0:55. And 2:30-2:45. And 5:49.

[@Murtagh653]

I come to the ATOH comment section for all the "they are on TV so they must be right and I am morally superior because I pretend like I know more about this topic than anyone else in the comment section" comments

[@southlakelife]

@@joncrosby8988 Boom

[@dogcreekproject6872]

There you go Donald!

[@beachboardfan9544]

Aaaalright great scott hahahahaha

[@hotpocket8624]

Beach&BoardFan aaaaaalright

[@MoneyManHolmes]

Great Scott! That turned out nice.

[@gabemalcolm4429]

LOL!

[@ytown]

Beach&BoardFan I was waiting for it and finally heard it at the end lmao!

[@AdamDrumm]

Beach&BoardFan 10/10

[@King_TuTT]

I just love your channel and content! keep it going guys! :0)

[@OnlineWaterproofingShop]

Don't really see the point with the drainage pipe, what was the fall across the length of the retaining wall? How is the dirt going to be washed out of it over time so it can continue to function?

[@trandall8]

I had understood you should NOT place landscape fabric behind the wall as eventually, that fabric will clog with soil and actually prevent proper water drainage through the gravel. Any input on that?

[@KnightofAntiquity]

T Randall Depends on the fabric. Certain fabrics are meant to do exactly what you are worried about so soil doesn't get into the gravel channel. If soil builds up there it won't drain.

[@spressne1]

Where did you source the block from? I'm not finding any that stout that have that level of interlocking.

[@PWL20Y]

its teco block

[@mae2759]

Check out Versa-lock. Similar, but with pins instead of those sliders.

[@jbhootgrass]

Base under wall should be 3/4" minus compacted gravel, not 3/4" clean gravel as it does not compact as well and you wont have a solid base to lay your first row of blocks. 3/4" clean gravel is fine behind wall for drainage but seems like they cut a corner by not using minus on the base.

[@aztekwarrior518]

"it'll look nice with our house too..." "Yeah.. Good, okay.." Aka: Shut up and let me do my job

[@bblack340]

Beautiful thumb nail

[@oscarmuffin4322]

Surely the fabric should have been under the gravel as well? Just from my experience of septic soakaways that gravel under there will fill with mud then you're back to square one.

[@mattt555]

I think the fabric is removed. It was just there to keep stuff out of the way. Fabric would stop water and fill with mud and stuff and cause it to fall.

[@mae2759]

@@mattt555 There are fabrics that are very water-permeable called "Non-woven geotextile fabric". Standard "landscape fabric" you use to keep weeds out would not be used here, since that blocks water like you said.

[@zhugeliang777]

@@mae2759 so he puts the permeable textile to keep mud at bay but let the water drain out? cool!

[@aquariuswithfire]

Does the perforated drain pipe empty anywhere? They didn't show where it emptied to. Or is it supposed to act as a seep reservoir?

[@kirkswenson7566]

aquariuswithfire There is a major void in most videos to provide guidance as to how to properly arrange the drainage pipe. Do you cap it? Do you have it pitched? Do you wrap it with a landscaping fabric sock? Do you lay it level? It’s odd that this topic is so commonly passed over in retaining wall videos.

[@levistrauss5378]

What you need are tiebacks

[@gregorybusby9889]

Where can i get these blocks?

[@tysmith7646]

If the drainage pipe is perforated how does water run through it to the end. Can anyone explain? Like if there are so many holes I don't get it?

[@hardkore360]

The perforations on the drain actually allow water to GET in and carries the water away from where it is rising or puddling

[@AllAccessConstruction]

Man I wish my walls was this easy... 😅 😅 😅

[@bobsagget9212]

Can someone explain why he put fabric behind the wall? Seems like it would trap the mud and push the wall over instead of letting the water drain through

[@scottrandall8502]

My take is that cloth is porous.

[@lovealwaysjasmine]

Can I use a retaining wall on a driveway that has a drop off? The drop off is right outside the garage so if I back up too far I’ll fall in the ditch 🙄

[@marcosmota1094]

*Imgur* is your friend. Upload a pic.

[@YadaYadaYadadada]

Would it be good or bad to use the sock to cover the perforated pipe?

[@AStanton1966]

Wouldn't hurt; more the merrier.

[@kimfucku8074]

Why is everybody having so nice dry and sandy earth? I have to battle with hard loamy earth all the times.

[@Rick-tb4so]

Does it matter what size stone you use and why ??

[@firesurfer]

It depends on the height and type of application.

[@PaverPat]

He did so much in under 6 minutes

[@philxdev]

^^ these stones are overkill but are pretty good.. but the old once would suffice if the wall was built properly.

[@fishon8406]

Maybe two courses high, no more. There is no weight in those small bricks to hold anything back if used on a wall even this low - looked about 24-30" tall.

[@hectorherrera5983]

How much do you charge for feet!!!

[@claireschofield6118]

Hi matey sorry to tell you Need to come round to our house

[@Aaron_Higgins]

If that retaining wall is supporting the neighbours property then there is a very unusual soil friction angle...

[@sgvpotter]

after digging out for the first gravel, why wouldn't you put fabric first, then add the gravel for the base? Why would you add gravel then the fabric?

[@ClicketyClack]

The fabric is there to prevent dirt from filling the voids in the gravel.

[@dialecticalmonist3405]

+Clickety Clack "The fabric is there to prevent dirt from filling the voids in the gravel." What prevents dirt from filling voids in the fabric? And if that happens how is that different from filling voids in the gravel?

[@firesurfer]

@@dialecticalmonist3405 There is a space between them. It would have been better to have more clearance from the fabric and the block. The space prevents the fabric from loading up.

[@carlosalbertotararantantan3866]

Ya lo hize,PL that set.

[@starlightengramA]

Some years ago I conceived a notion to pour concrete into forms, and then to put them in a pressurized chamber to set up and harden at 2 to 3 atmospheres. An air compressor, hose, some fittings, and a sealed reinforced enclosure pressurized to high pressure would compress the mix and squeeze out the air bubbles. The blocks would harden at preloaded compression forces and theoretically perform as superior barrier blocks against high weight loads and point intrusions, and probably resist torsional and flexural forces better than standard block also. I want to build a "hard room" but it's not for a bullet-proof case. I want to build a machine that is possible (in its test phase) to require containment if it flies apart when it is revved up. The method may even produce high density block performance made with admixtures of space expanding foam particles to lighten the weight but with extreme block strength. Savings in shipping and ease of installation would then help a lot. Are there no videos on the subject?

[@Matixx02]

I would think instead of pressurizing the container to form the concrete, you would want to pull under vacuum. This would pull all the air bubbles out.

[@michaelbreslin2403]

Matixx02 If you multiply the equivalent mass by 10 to the negative third you get the same result.

[@PAFloridian]

At the 5.46 mark that chick pulled away like she got slapped. Hilarious

[@josephbella23]

The OS i

[@robs1852]

Something invisible happened

[@BarriosGroupie]

The main problem with the original wall was the lack of back-fill. There's no need for the drain pipe because the water is meant to leak out the front bricks.

[@ecospider5]

Filter fabric is a no. It gets clogged eventually and then does not let the water through. I am just trying to quote Dirt Monkey on this one. I would take his opinion above others. I am not a contractor so please explain if I’m wrong or misunderstanding The Dirt Monkey videos.

[@GlennMBrown1]

I think it was removed after it served it's temporary purpose during installation... but idk..

[@dannyescobar870]

How much can I charge for doing this job

[@southie1231]

Who manufactures the blocks used in this episode?

[@matt94372]

Looks like Unilock

[@davidwyatt4061]

Techo-Bloc Mini Creta Wall System WWW.Techo-Bloc.com

[@theedrstrangelove]

4 years of season changes and I bet this wall is starting to look like the old one. Should have poured a high strength concrete wall.

[@Burn269]

The best repair to fix a failed block retaining wall, use solid concrete.

[@Burn269]

Joe Stacks I couldn’t agree more. A failing leaning pieces of block wall looks atrocious. Solid concrete walls are the way to go.

[@707SonomaComa]

For really good explanations check out Stanley "Dirt Monkey" Genedak. He explains it all very well. This guy did a good job too. Looks good.

[@ClarkJohnson]

Stanley says not to put vertical fabric behind a retaining wall, but that's what this video shows along with almost every other how-to out there.

[@firesurfer]

@@ClarkJohnson Stanley says to not put it immediately behind the wall. Here they put it back a few inches away from the block with stone in between. (One foot away would have been better) Also, this is a very short wall, designs for anything over 3 feet are much different.

[@raymondlopez7235]

Nice how much?

[@ericcarlson6815]

Won't stacking the geo tarp vertically like that create a barrier for the water causing the same issue they already had?

[@MoneyAndPeople]

there is a lot of drainage behind that wall, it would take 20 to 25 inches of water coming down at once IN WINTER to cause the same issue (water getting into cracks > freezing > thawing > bigger cracks > repeat), basically overwhelming the ample drainage, and this would have to be repeated a lot times before any evidence of the issue occurs. The show is film in North America, thus the chances of that much rain in winter is low and snow stays where it lands until it melts. There main issue was with the mud (dirt) behind the wall getting hard and moving the wall. French drains (the piping) are also very effective.

[@ericcarlson6815]

@@MoneyAndPeople yeah but the tarp is placed behind the drainage, how is the water supposed to get through that into the drainage material?

[@MoneyAndPeople]

@@ericcarlson6815The tarp is very thin (see around 4:10 ) it is like a screen on the windows, except much thinner.. ie if you had it on top of a glass, you can poor water through it, just much slower - another name for this product is landscaping tarp (google image search "landscaping tarp" )

[@ericcarlson6815]

@@MoneyAndPeople oh ok, I had assumed it was like a polyethylene tarp

[@jdjd2059]

Yep, build the wall!

[@realmccoy2269]

$4,000???? Screw that, I'll get Mexico to pay for mine

[@tezoyo6848]

jajajaja no quieres ayuda con tu vieja igual lol

[@dicklongson683]

@Real McCoy build a wall around your mom.

[@brendanboyle9327]

Anyone looking for a verrry similar guitar rift should listen to insane clown posse, homies. Jordan Critz must be a serious juggalo! 😂😂😂😂

[@youredoingitwrong1361]

1:53 scotty doesn't know

[@finkthreely7089]

P r e f e r a t i o n s

[@AStanton1966]

I have yet to see any concrete block hold their color and not turn black or gray from sun and water. If you want to keep the original color, you need to use natural stone.