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White Gardens
07-24-2011, 10:08 AM
So what's the best way to set the first course of a retaining wall.

I do it the way I was taught, which is to get your compacted fill as close to level as possible, then use fill sand to set the first course and tweak when needed.

I end up using as little of sand as possible, but struggle along sometimes where my base might be a little off.

So, my thought is to come up with some sort of screet rail that's 1/4" or smaller to screet off the sand to get a more consistent base to speed up the first course. The only problem is that I wonder if too much sand will settle and throw the wall off over time.

The problem I see with a small screet rail is it getting tweeked or bent over time and then not really helping me out.

I've only done a handful of walls where they are only a couple of 2-3 courses and caps. I can see that doing any larger walls where I'm going up 4 courses or more can create problems if the first course is not quit 100%, thus leaving the caps with slight imperfections when butting them up.

Any thoughts?


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STL Ponds and Waterfalls
07-24-2011, 10:56 AM
As long as your an inch or under you'll be fine. Get you base to spec and if you start to see more base being needed to level off add some more and compact. If you have to and it's possible run a stringline to see your low spots and adjust your base where needed. I know NCMA specs sand for a base but I prefer to just use 1" minus or whatever your base material is called.

A lot of times your block can be off spec by a 1/8" or so and that maybe why they don't totally line up for your caps. Pennies and a cup grinder can be usefull in shimming your block if they are really out of spec.

White Gardens
07-24-2011, 11:27 AM
As long as your an inch or under you'll be fine. Get you base to spec and if you start to see more base being needed to level off add some more and compact. If you have to and it's possible run a stringline to see your low spots and adjust your base where needed. I know NCMA specs sand for a base but I prefer to just use 1" minus or whatever your base material is called.

A lot of times your block can be off spec by a 1/8" or so and that maybe why they don't totally line up for your caps. Pennies and a cup grinder can be usefull in shimming your block if they are really out of spec.

Thanks.

Basically from your post I'm probably just splitting hairs too much when installing walls and that's what's throwing me off. Most of the time I use string lines for all my projects as I haven't done enough hardscape work to warrant buying a lazer yet. I usually have 5 line levels with me and use the two or three that give me the same consistent bubble reading.

Good call on the pennies and thanks for that tid-bit of info, I like that idea as sometimes I can be off by just a fraction, but then makes my caps look off to the trained eye. I just got done with a very short wall where the center had an engraving on the cap. I had to do some very minor tweaking so that the letters that crossed the seams of the cap had to line up perfectly.

For screet rails, I'm thinking of going to a steel shop and see if they have any square or round rod at 1/4" or so to use for rigidity. Then ultimately store them in a section of PVC pipe or similar to make sure they stay true during transport and storage. I hate the idea of using conduit for rails and having them get tweaked real easily.

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SVA_Concrete
07-24-2011, 11:41 AM
i would like to learn more about this Screet thing and the lazers

STL Ponds and Waterfalls
07-24-2011, 12:05 PM
WG, so you don't get your balls busted any harder it's "Screed" and "Laser". :)

Stillwater
07-24-2011, 12:15 PM
So what's the best way to set the first course of a retaining wall. Any thoughts?....



For block walls I have 3 ways, Time, more time, and a little more time. Frustrating as it may be for me I accept the fact that this will take time. I do not look for any short cuts on first course. I accept nothing but dead on level. No creative shimming, no creative screening, no looks good from my house crap, or it's good enough. just time and crusher run or what ever I am using for a base. Time is paid back to me later in the install when I can fly through it. When I pull out and warranty begins the last thing I want to be thinking about is the creative shimmimg or sand that may or may not move because when it does move (my personal opinion it will) So the politically driven money grubbing NCMA can shove their arbitrary ever changeing on a whim specs up their *** Its not their money that will pay my labor bill during a service call it's mine. I sell labor, and time is what I sell...

White Gardens
07-24-2011, 12:20 PM
i would like to learn more about this Screet thing and the lazers

:laugh::laugh::laugh:

Nice catch. The boy has been up since 4am and my mind isn't working correctly.

Maybe I was also was thinking of the cheap 40's I used to drink back in the day. I think it was spelled with a z.

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White Gardens
07-24-2011, 12:42 PM
For block walls I have 3 ways, Time, more time, and a little more time. Frustrating as it may be for me I accept the fact that this will take time.

Agreed Stillwater.

I just want to do it right and make sure the wall stays level after installation. But at the same time, I'm trying to take a little of the frustration out of it.

The thing I hate is when you think you've done it right and you get off by an 1/16th of an inch or less on the caps. Even though it's close, I want them to line up perfectly.

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scagrider22
07-24-2011, 12:55 PM
The easiest way for me to put base down is with a rotater, I have a guy walk in front of me checking the grade about every 1-2' and I correct it with a rake until it beeps level (I only do this on the final lift), then I run the plate compactor over it to smooth it out. I do not use any sand and my first coarse of block goes down pretty fast.

DVS Hardscaper
07-24-2011, 06:24 PM
One inch of sand is too much. We barely use 1/4" max.
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SVA_Concrete
07-24-2011, 06:37 PM
sorry, I couldn't resist.

i agree 1 inch of sand is far too much, we use handfull's of stone dust (fines out of the base material) to level out the first course and pound the block in with a dead blow hammer. use a 8 foot level to run across the first course

DVS Hardscaper
07-24-2011, 07:58 PM
"8' level"? I don't agree with that. A laser level or an old fashioned transit will prevent the piano key effect.

SVA_Concrete
07-24-2011, 09:58 PM
"8' level"? I don't agree with that. A laser level or an old fashioned transit will prevent the piano key effect.

we use a laser as well for the base material, but... when i am laying i prefer to use a large level to slide across the top of the block as both a level guide and a straight edge. works on straight walls or radius walls.

i know i don't have a thread thanking my existence on the earth.... but that's how i like to do it.......to each their own.

SDLandscapes VT
07-24-2011, 10:31 PM
ziplevel over laser

zedosix
07-24-2011, 10:39 PM
We use screed rails set up with a lazer, placing them wider than the wall of course. Screed granular, compact, then finish with stone dust. Set the blocks and use a dead blow to level them front to back side to side.

DVS Hardscaper
07-24-2011, 10:49 PM
we use a laser as well for the base material, but... when i am laying i prefer to use a large level to slide across the top of the block as both a level guide and a straight edge. works on straight walls or radius walls.

i know i don't have a thread thanking my existence on the earth.... but that's how i like to do it.......to each their own.


There is certainly nothing wrong with using an 8' level, but I think SVA has a knack and passion for good work, which is why it works for him.

My guys forget that perfectly level block and block all of the same grade are equally important, yet two different things. So with my immigrants I find it easier to have them use the laser.

all ferris
07-25-2011, 10:58 PM
I have always pondered the idea of using Form-A-Drain as screed rails? I mean they use it for house foundations. Why not retaining walls?

PatriotLandscape
07-26-2011, 11:19 AM
I use hold out my arm, raise my thumb and squint.
Posted via Mobile Device

Stillwater
07-27-2011, 12:17 AM
ahh the old thumb and squint

2brothersyardcare
07-27-2011, 11:38 AM
when i did one early this year i put 1/4 inch of stone dust my dads guys did it and they said stone dust this right?

DIXIECONTRACTING
07-27-2011, 11:57 AM
We use crushed stone find it packes best in all weather

joes169
07-27-2011, 12:36 PM
We've always set forms to grade on the front side of the wall, about 12"+ in front of the SRW wall. Stake the forms in, either 2x4's for straights or plastic flexible forms for curves, set level with laser, fill in lifts to top of form with gravel, fill in remaining distance between compacted gravel base & top of form with sand, typically less than 1/2". This may seem like extra work, but we're really concrete & masonry contractors, and the forms ride with us everyday in the trailer anyways, and forming is elementary to us.

There are other benefits to the forms as well as they create a good median to mark off of, you can judge your curves off of them as you go along, the open trench in front of the form offers a quick way to lose extra material as you're screeding etc.....

And we always set the forms with a laser & use a 4 or 6' level for the balance of sand screeding.

stuvecorp
07-28-2011, 12:44 AM
We've always set forms to grade on the front side of the wall, about 12"+ in front of the SRW wall. Stake the forms in, either 2x4's for straights or plastic flexible forms for curves, set level with laser, fill in lifts to top of form with gravel, fill in remaining distance between compacted gravel base & top of form with sand, typically less than 1/2". This may seem like extra work, but we're really concrete & masonry contractors, and the forms ride with us everyday in the trailer anyways, and forming is elementary to us.

There are other benefits to the forms as well as they create a good median to mark off of, you can judge your curves off of them as you go along, the open trench in front of the form offers a quick way to lose extra material as you're screeding etc.....

And we always set the forms with a laser & use a 4 or 6' level for the balance of sand screeding.

Must be a Wisconsin thing.:) I use the plastic flexible forms as well, I think it goes pretty well compared to the old beat the block in to submission method.

xtreem3d
07-28-2011, 04:31 PM
Can you guys post a link to what forms your using? i googled some and most look "weak". Also what height are you finding works best?
Thanks,
Steve

joes169
07-28-2011, 08:45 PM
We have a few sets of these forms in 4" height:

http://www.metalforms.com/concreteFormingProductsDetails.asp?cat=Poly+Forms&ID=12&pID=20

As mentioned, we use them almost exclusively for concrete flatwork, so we chose the 4" height. They still work fine for retaining wall bases, although I suppose 6" might be ideal if that's all you use them for.

AztlanLC
07-28-2011, 10:50 PM
We get the base as level as possible then spread about 1/2"-3/4" of 3/8" clean stone and use 4' level to screed, install the whole first course and hit them with the hand tamper then do minor adjustments but most of the times it's perfect.
it takes 3 guys about 1 - 2 hrs. 100 lf. depending on shape and size of blocks