# Interlocking Block Garden Wall



## joetab24 (Apr 10, 2009)

I'll let you know up front I've never done this before, but I am a firm believer in learning as much as I can and being patient, so that the end result is a project well done.

So far I've dug a trench. Yesterday, I had some help. I was pressured a bit by my well meaning but pain in the butt! dad to move a little quicker than I have been. 

We put a layer of stone down and some paver base. The problem is there is still a decent slope in the trench. (in the photo below the ground slopes from bottom of the screen to the top). 

Somebody who has done this before said I should probably build up to the higher end by digging deeper on the low end and adding an extra row of rocks. 

You may be able to detect the slope of the trench in this picture.
http://tinyurl.com/czn3f2

I know I should have done this better before adding the stone, but I set the stones to the desired height, 3 rows up. I then pulled a string so that it was at the same height and then I used a line level to make sure the string was level. This morning I made a water level and I think I am going to use that to get a level line. 

http://tinyurl.com/cdqc82 http://tinyurl.com/dxlgtq http://tinyurl.com/dc7b2s

I am now going to have to work on digging the low end deeper. So I will remove the stone we put down and dig deeper to add an additional row of stone, otherwise if I try to level the low end with the high end, some of the first row will not be below grade. Rookie mistake, but I will fix it. 

Some earlier pics
http://tinyurl.com/ccf438 http://tinyurl.com/dbhb5l http://tinyurl.com/cl84bm 

Thanks for taking a look.


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## 47_47 (Sep 11, 2007)

The hardest part is getting the base right. After that the wall will fly up. Yes you'll have to level the base course first. I'd carefully remove the base material to either a tarp or wheelbarrow and level the grade. 1/2-3/4 of a block is enough below grade.

As a side note, where are you planning to do with the downspout in pic 3? I wouldn't have it exit behind your wall.

Here's my wall from last summer. Take your time it is not a race and it will be fine.


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## joetab24 (Apr 10, 2009)

Thanks for the reply. I am definitely going to move the downspout extentsion. A few people have given me ideas about how to deal with it.

Should I end the wall against the right patio pillar?
http://tinyurl.com/dxlgtq

On the left side, I start against the pillar. This is where my property begins.

Here is a wider view

http://tinyurl.com/cl84bm


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## 47_47 (Sep 11, 2007)

You could turn it back to the right pillar for symmetry or extend it out to the driveway and make two turns back to the pillar. It looks like you have less than 2', I'd lean that way. Do a dry run and decide. 

Either way do not butt your wall to the house/porch. Leave a gap (1/2" or so) to allow for movement of the wall.


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## joetab24 (Apr 10, 2009)

*interlocking blovk garden wall*

I've been watching this video a few times to get some visuals. 

http://www.thisoldhouse.com/toh/video/0,,1632351,00.html

At about 2.15 he checks for plumb against the mason's line. Do you put the level anywhere on the block to do this? I think he says something about the front of the block. I probably should know this, but I don't.

Additionally, how do you make sure you are laying the blocks in a straight line? Did you use a mason's line? If so, should the line touch the front of the block?

Also, some people have suggested knocking off the lip of the block for the first course. 

And finally, did you use adhesive for each row. I was under the impression this should only be used for the top stone (capping?) if you are using interlocking blocks.


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## joetab24 (Apr 10, 2009)

*interlocking block garden wall*

I also haven't squared the corners of the wall using the 3, 4, 5 method. I really hadn't considered this until I was looking through a DIY book from the library. The example in the book was on flat ground. I already have a flower bed so the surfaces are not even. I guess this can be solved with stakes and a plumb bob. Any tips here are appreciated greatly.


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## concretemasonry (Oct 10, 2006)

Just look at the installation instructions on one of the internet sites by the international segmental retaining wall licensing companies (Allan block, Anchor, Keystone or Versalok). They all have great information that you do not get from the "knock-off" versions.

The first or bottom course should be level or you always fighting through the installation.


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## joetab24 (Apr 10, 2009)

*interlocking concrete blocks*

Concrete,

Thanks for the reply. I was able to find that Home Depot's Windsor blocks are made by Anchor. There is another company called Pavestone who seems to have info about the Windsor blocks.


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## kimberland30 (Jan 22, 2008)

I just finished a low retaining wall around our tree, and it definately helped to knock the lip off of the first course. We compacted the soil and added paver sand, and without the lip of the stone it was easier to get level. 

When placing our block, we leveled each one by taking a small level and placing it across the stone and from front to back. We also made sure the placed stone was level with the one next to it. Every few blocks I'd put the 6' level on it to make sure it was still straight. I purchased a line level but never used it, the regular levels worked just fine. 

It's a PITA to get the first course level, but so worth it. Like another person said, once that first course is down the rest will go very quickly.


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## joetab24 (Apr 10, 2009)

i haven't done much since this post because i'm waiting for my new patio to be installed. 

i did, however, work on a small section to practice setting the blocks level. i set 3 blocks in 2" of paver base and used leveling sand to level them. i did not fill the whole trench with paver base because i found it easier to add the base, tamp, and level as i moved. it then rained for a few days and the blocks shifted slightly. i don't see myself being able to get the whole first row done in one day. besides praying for a dry spell, would it make sense to add dirt to the front of the block and backfill stone as i move from block to block to keep them in place?


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## 47_47 (Sep 11, 2007)

Joe, 

The one course of block will move. The lock together as you add more. 

Dry lay the number of course of blocks you plan to use and measure the height of the wall, add for your compacted base material and sand thickness. Set your level string line at the top of your proposed wall and measure down this distance. Take your time and do not disturb any more soil than necessary. 

Once done, add and compact your base material. Use the level line and spirit level to get as close as you can to the finished grade height of your compacted base. Now start laying your first course. Use a hand held level and your string to double check as you go.

Added: Estimate your time. Plan on 65% of the time digging your soil and leveling your compacted base, 25% setting the first course and only 10% to finish.

Good luck.


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## jomama45 (Nov 13, 2008)

Joetab, to save a little time on the first course, here's a few things I would do.

- Chisel the majority of the lip off the bottom of the block for the first course. 
- Set your string out a few feet in front of the wall, use a tape measure to reference if occasionally.
- Use a four foot level for the tops & to range the back for the first course.
- Use a four foot level to screed your sand PERFECT before you set block.

If you do these things, you should be able to merely tap the block around to level. And if the block aren't perfectly straight on the back (try to keep within 1/4"), the rockface does a good job of hiding it. Have fun!


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## Tscarborough (Mar 31, 2006)

A couple of things. First, place the string at the rear of the block. The front is split faced and can vary as much as 1-1/2". Second, to get the base course right, you will need a small level and a big level. I use an 18" to level front to back and a 4' to measure down the wall line. This allows you to find small irregularities and the longer the level the more accurate the reading will be.

Knock the lips off, I just beat them with a brick hammer, since it doesn't have to look pretty. Keep a bucket of fines (bigger than concrete sand) with you as you work each block for leveling, and spend the time to get them right. For big walls, I allow 15 minutes per unit when estimating my time.

To make curves, be sure that the gap between each block (at the rear) is the same, and the curve will be perfect.

If the ends are constrained, work from the ends to the middle, so that your cut closer will be lost in the over all wall, and will not compromise wall integrity. If the closer is less than half the width of a block, cut a little off of 2 rather than using a small piece.

If the base of the wall steps down, make the step down at least 2 block into the hill. Step downs are the most common point of failure because people are too lazy to dig that extra little bit.

Good luck and drink lots of beer!


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## Tscarborough (Mar 31, 2006)

I just looked at your pics. You should probably curve that corner by the downspout. That is an easy mornings work. You may be over thinking it.


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## joetab24 (Apr 10, 2009)

guys,

thanks so much for the feedback.

I am finding that I am having a difficult time tamping the soil level. It's close, but I keep finding irregularities. The soil is moist and fairly pliable, since it has been raining so much here in PA. Is it ok to add the paver base and level that or do I have to get the dirt perfectly level? Also, am I supposed to add an inch of sand to the whole trench, or just use the sand to level?


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## Tscarborough (Mar 31, 2006)

The dirt only needs to be nominally level, the base is what you level.


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## Zel1 (Mar 21, 2007)

I built 3 of those walls at my house with some help on the first to get the concept down. Like was said above, get the base level, then level each block as you put them down. Check each, with the ones you previously installed with a 4' (or larger) level. 

When we finished building the walls, I went back to Home Depot to get the caps. I was told they didnt have them and I was only able to order a skid or more. I only needed about 40-50 of them, so I wasnt going to order hundreds of them. I called Anchor and they told me that a customer ordered a large quantity and returned a portion of them to another Home Depot almost 2 hours away. I called, varified they had them and went to pick them up. Thats when all hell broke loose. The manager I spoke to was helping me load them up when another manager said "they are not for sale. They were special order and we dont have a skew for them, etc, etc. " This guy was determined to have me unload them from the truck and drive 2 hours home with no caps. The other manager really went to bat for us and charged us for a different wall cap they actually stock. The manager with the problem turned his back to deal with someone else, we paid and got the h*ll out of there before he noticed. lol.

Bottom line is, if you want caps for that wall, make sure you can get them first.


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## joetab24 (Apr 10, 2009)

I was wondering if Depot had the caps. I picked up some paver base from Depot. I assumed this would be fine to use as a base. Am I right? What did you use as a base?


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## Zel1 (Mar 21, 2007)

I used 3/4" modified stone. Once tamped down, it was nice and smooth. If I remember correctly, those Anchor blocks dont recommend using sand to level, just the modified stone. I think the paver base should be fine. I think they sell "paver base step 1" (3/4" modified stone) and "paver base step 2" (filtered sand). Make sure what you have is the 1st step stuff.

I helped my dad do a 18x12 patio last summer. He ordered 3/4" modified stone and wasnt there when it was delivered. They delivered some crushed granite and he didnt realise it was incorrect. He wheel barrowed it through the house and into the yard. We arrived with the tamper and knew right away it was the wrong stuff. It took forever to tamp and we were using a gas powered plate compactor. We knew we should not have used it, but stubborness prevailed.


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## chigundo (Apr 27, 2009)

Here's my new wall. The installers felt that it's too low to require crushed stone.. they said just landscape fabric and soil will be fine. But because I'm in charge of the backfill, I feel like adding crushed stone to be safe... the distance of the wall to the dirt behind it is only 6 inches or less in most spots.. so it's not like I have a thick area to add stone to.

What are your thoughts?


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## chigundo (Apr 27, 2009)




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## Zel1 (Mar 21, 2007)

That wall looks incredible. I dont know if I would accept not using crushed stone under it though, but if they are a reputable company and gaurantee it, then I guess live with it and see if anything changes.


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## Scuba_Dave (Jan 16, 2009)

Where are you located?
Its better to start a new thread then adding on to someone else's thread

1st pic looks like its already back filled ??


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## chigundo (Apr 27, 2009)

I'm located in West Hartford, Connecticut.

It's not backfilled yet. That first pic is just the existing garden behind the wall, there's a few inches between that and the wall itself.

The wall is built on what was extremely condensed clay soil and compacted stone dust.


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## kimberland30 (Jan 22, 2008)

I would just use native soil in your case. Compact it as you go. Since it's a clay soil you should be fine. The weight of the block will hold it together and I don't think you need anything behind it to keep it sturdy.


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## joetab24 (Apr 10, 2009)

*Retaining Wall*

Alright, I can finally get back to this project, since our patio is finally finished!

This will be a small garden wall, about 19 feet wide and less than 2 feet high. I am using 3/4" crushed stone as my base. I then put down some home depot step 1 paver base so that I could level everything better. The crushed stone is rather jagged. This is a very fine crushed stone. It reminded me of "stone dust," which I've seen used on some DIY tv shows. I figured it would be better to use this material than sand. Is this ok??
It is taking me about 15 mins a stone to level in all directions. From what I've read this is about right??

Also, because of my schedule, I know I will not be able to dedicate more than a couple of hours a day to this project if I am lucky. With two little ones and a wife who stays at home with them all day, I can't spend huge amounts of time completing projects. Anyway, I covered the section I had leveled (three stones so far) with a tarp. I am really concerned at this point that if it rains all of my work will be ruined. Or should I backfill the area I've completed and put dirt in the front so that it is more secure? Thanks for your help!


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## joetab24 (Apr 10, 2009)

*3 Retaining Wall Questions*

1. My trench is about five feet from a maple tree. I am noticing tree roots as I dig. Most are small, a few a about 1/4". Is this going to be a problem? If so, is there anything I can do? The roots move toward the front of the wall.

2. Am I supposed to put any crushed strone in front of the interlocking wall blocks, or do I just fill with dirt?

3. Should I put a perforated pipe behind the wall? The wall will be 16" high. One foot above grade. I am going to use 3/4 clean crushed behind the wall. 

Thanks!


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## joetab24 (Apr 10, 2009)

*retaining wall*

i've attached a pic


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## joetab24 (Apr 10, 2009)

*some more pics*


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## joetab24 (Apr 10, 2009)

no responses ??


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## Joe F (Jan 27, 2008)

A pro might weigh in and disagree with me, but...

1. I don't think you need to worry about the tree roots.
2. No need to put crushed stone in front of the wall. I think I'd make sure the grade slopes away from the base of the wall slightly.
3. I don't think you need perf pipe behind the wall if you back fill with gravel and use filter fabric.

Looks to me like you have a pretty stout wall given the relatively low height. i.e. large blocks, stepped back etc..


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## 47_47 (Sep 11, 2007)

No pro, but I agree with Joe^


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## joetab24 (Apr 10, 2009)

thanks guys! I am almost done course #1, so I should get this done soon.


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## joetab24 (Apr 10, 2009)

*Estimating Back Fill*

Figured I'd start a new thread since I have a new question.

I am trying to estimate how much stone (3/4" clean crushed) to purchase as backfill for my retaining wall project. (I am sure I should know how to calculate this!). Course #1 consists of 20 11.5" long blocks. The blocks are 4" high and I have gone 5 courses high. I am not sure how high I have to go with the crushed stone; I think I saw at least 6" on a site, but I have to check.


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## Brik (Jan 16, 2007)

The stone is sold by the cubic yard. One cubic yard is 27 cubic feet. (3x3x3). One cubic yard will weigh about one ton. Its also about one "scoop" of a front end loader at the supply yard. Around here, one "yard" meaning a cubic yard sells for about $20-$30 not including delivery.

if your wall will have 1 foot of stone fill behind it and is 10 feet long and 3 feet tall you would need 3x10x1 or 30 cubic feet or a little more than one cubic yard.


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## joetab24 (Apr 10, 2009)

thanks Brik!


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## joetab24 (Apr 10, 2009)

*retaining wall---how does this look?*








I still have some work to do but the bulk of the job is finished. Becuase my property slopes ,only 2 of the 4 rows are visible on the high end. Does that look odd?

Left to do

finish adding dirt in front of blocks
backfill 3/4" clean crushed
level dirt behind wall
add some plants
replace downspout extension
reseed lawn


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## joetab24 (Apr 10, 2009)

This is the BEFORE pic


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## Scuba_Dave (Jan 16, 2009)

Looks good
I think I might have dug the other side out
But sometimes thats a lot of work
I hope you didn't bury the 2 rows.
I just use rock under level of the ground to bring it up to where I need it


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## joetab24 (Apr 10, 2009)

Scuba,

Thanks for the reply. I did bury the two rows. So you would dig out some of the dirt that is blocking these two rows on the high end? I don't mind doing the work, but I have to figure out what to do with all of the dirt. I already have a large pile behind my garage (don't tell my wife!)


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## Scuba_Dave (Jan 16, 2009)

As long as it wouldn't create a slope towards the house - yes


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## jomama45 (Nov 13, 2008)

Personally, I like when the grade changes at the bottom of the wall, & the top carries through at the same height the whole way. I've done quite a few Versa-Lok walls through the years, & I have to say, stepping the top of the walls takes alot away from the wall asthetically, IMO. As for your wall, the grade change is so subtle, I wouldn't bother digging any more soil out. The only thing I would possibly recommend, & this is definately preferance, & a lot more work, but a solid cap with an inch of overhang over the front of the wall would look very nice. To me, that's usually the difference between an OK wall & a great wall. Either way, good results for all the labor it ensued. :thumbup:


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## joetab24 (Apr 10, 2009)

I've thought about adding the capstones. Depot doesn't carry them, but I can probably get them somewhere else. Do they have to be cut, or do they just line up?


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## jomama45 (Nov 13, 2008)

Normally, they are made to fit without modification on straight walls, but definately need modding on radiuses. That's why I mentioned it would add alot more time, but it may be worth it.


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## concretemasonry (Oct 10, 2006)

It looks great and that is the best way to do it. For more sloped sites the first course can be stepped as long as you have the proper burial depth for that part of the wall.

The better retaining wall suppliers usually make caps with square ends and slightly mitered (either short front or short back) that can be combined to make different radius turns (inside or outside corners). Some people chose to go with unsplit caps to provide a more finished top.


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## joetab24 (Apr 10, 2009)

As I mentioned I haven't backfilled yet, am I ok not using a perforated pipe or would you? Several people have said it was not necessary for this job.


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## joetab24 (Apr 10, 2009)

this project has cost me 365.52. I had to buy all of the tools (wheelbarrow, 4' level, sledge hammer...). I still have to buy the crushed stone for the backfill. If I can get a truck, that will be a small expense (I think). What do you think a pro would have charged?


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## Scuba_Dave (Jan 16, 2009)

joetab24 said:


> As I mentioned I haven't backfilled yet, am I ok not using a perforated pipe or would you? Several people have said it was not necessary for this job.


Seems like you have a gutter above this
So roof water is not going into this area
Based on the size I'd say not needed
Gravel is backfilled along the wall to prevent freezing ground pushing the wall out
---ops - just noticed you are aware of that :thumbsup:


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