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View Full Version : Setting the base couse for a wall


R.M Hanson
06-17-2007, 05:46 PM
I've been building retaining wall for almost 10 years, and there has got to be a better way. I was wondering if any of you guys had any tricks or tips for making the base course of a wall easier to install. I've tried a few different ways, but all I can say is that it's a time consuming, slow, and stressfull process. Right now the system I use is pretty old school. I start by excavating the area with either a mini-ex or the skid, and lay down a base of compacted stone, using a thin layer of some stone dust for setting the blocks on. I use stringlines to keep the wall straight, and 3 different sizes of carpenters levels to make sure my blocks are all level. It seems like I spend most of my time adding or subtracting tiny amounts of base material, moving the blocks in and out several times, and swatting the heck out of the blocks with a big deadblow hammer. It's a very slow frustrating, process and It's about enough to make me want to quit, but my walls always turn out nice, so it's a proven system. Any ideas to help speed up the process or to make life easier would be greatly appreciated.

carcrz
06-17-2007, 05:54 PM
I think that's the tried & true method. It's better to take your time & have it perfect than to rush through it & end up w/ a less than par wall & a dissatisfied customer.

New Heights
06-17-2007, 06:30 PM
Thats the same way I do it. I take my time and it allways comes out perfect. Try training your guys to do it so you dont have to, that is what im working on.

GreenN'Clean
06-17-2007, 08:14 PM
I agree its better to take your time and do it the right way then try to fly through just to finish the job.

zedosix
06-17-2007, 09:54 PM
I grade the entire area for the base course then lay the blocks in one shot.

greg1
06-17-2007, 10:31 PM
OK, sounds to me like you got it knocked. I've done hundreds of block wall projects since decorative block came out in the 80's. Some days you can lay 200' of base and some days you can lay 30'. It's frustrating for sure. For myself i get my base (3/4" clean) as close as possible, then i set down a skim coat of 3/8's clean. set the block down and drive her home with a commercial tire hammer :hammerhead: (rubber side of course). Check her every which way to sunday with a variety of levels and eye f#*k her to death on the radius. If she's off the slightest, rip her out and do it again.

ChampionLS
06-17-2007, 11:25 PM
It's very very simple. Excavate 6" wider than the block in both front and back for your base course of block. Excavate down 6" below the base course of block for your Aggregate base. Wrap the excavation with suitable geotextile fabric and install 2A type modified stone and compact. To set the grade for your blocks easily, screed rails of 1/2" pvc pipe can be placed in parallel close to the outside edges, and leveled off with a laser or transit. Sand or screenings can be applied over the pipe and screeded off easily to make a wide leveling pad the entire length of your wall. Simply lay the blocks on the pad end to end and your done. The hollow blocks below grade should be filled with 2a modified stone. At grade level, a drain pipe needs to be placed behind the wall and routed to daylight. Backfill at this point should be 2B clean stone inside all hollow blocks and 1' behind the wall. When reaching the top, end your drain field before the last course. Filter fabric may or may not be necessary between the drain stone and infill soils, but definitely needs be placed over the aggregate after the last course. Finish with a cap and grade.

neversatisfiedj
06-18-2007, 08:35 AM
Stone screed ?

iowa
06-18-2007, 09:52 AM
I use 2x6's screeds for straight walls and masonite on curves. Top half inch or so is stone dust to get perfection. Level the screeds with the laser and blaze through!!

LindblomRJ
06-18-2007, 10:42 AM
I use 2x6's screeds for straight walls and masonite on curves. Top half inch or so is stone dust to get perfection. Level the screeds with the laser and blaze through!!

Must be an old concrete guy?

mowingguy
06-18-2007, 01:51 PM
I built a little tool that has probably saved me days.

Took a four foot steel level and two pieces of 1/8th steel. Welded the first piece (4x10inch) to one end of the level. Drilled two holes into steel. Took the second piece of steel (12x 20 inches) and cut slots to match up to holes in other steel plate. Connect the two steel plates with bolts washers and wing nuts.

How to use.

Place one block on top of a skid. Loosen the wing nuts. Place the level portion on that block and retighten once the second steel plate touches on the skid. (You will learn that 1/16th to 1/8th gap is ideal.)

Set your first block in the base row exactly how you want it.

Place the level portion of tool onto block and move the steel plate back and forth through stone dust/sand. Repeat until base course is complete.

I do not post much but have a lot of walls under my belt. -SL

neversatisfiedj
06-18-2007, 02:00 PM
Sounds like the same thing .

https://www.kalcometals.com/stonespecs.htm

mowingguy
06-18-2007, 02:33 PM
That is darn close to what I built. I kept the bubbles in the level... might be the only difference.

Has anyone used something similar? -SL

R.M Hanson
06-18-2007, 05:20 PM
Thanks for the ideas guys, that stone screed tool looks pretty neat, it sure looks like it might make things go faster. I've also considered using the screed rail method, and using that to help as well. Maybe a combination of these different ways, combined with my old way will help speed up the process. I also have a good employee that I'm training to help me, and he has no experience building walls. He's a good worker though, and listens and wants to learn, and that's what's important. We just completed a 480sq.ft (face) wall, and have 3 more similar size walls to do this summer, so we'll be getting a lot of practice. My usual work is finish grading and seeding, and I build walls between projects. More and more home builders are landscaping the houses they build before they are sold, so business will continue to grow. Thanks for the ideas, and I'll let you know how things turn out on the next job.

McKeeLand
06-18-2007, 09:51 PM
Stone screed ?

i have tried ordering that but the web site does not take orders and the phone # goes to an answer machine that no one calls you back on.

ChampionLS
06-20-2007, 01:00 PM
I still say it seems like a good tool, but unless you keep checking the height with a laser, simply screeding the base next to each block will eventually leave you with a wavy wall. Best bet is to frame out your wall area with wood strips, masonite forms or pvc pipe- level it with a laser, screed once and your done.

richallseasons
06-20-2007, 05:03 PM
I use a laser, my good eye, elbow grease and patience, I am sure you all have come to realize that this is where most of your time is spent when building a wall, and I dont care how many gimick gadgets are out there its going to be time consuming. I tell me guys and myself for that matter all the time--- Take your time with the prep work because if your prep is crap then so is your finished product!

ChampionLS
06-20-2007, 09:53 PM
I forgot I even had these pictures. We dug a trench, put in 6" of modified stone for the base and tamped. Framed out around the base with cheap, simple wood furing strips that were leveled with a laser. Screed some sand or stone dust and lay the blocks on a perfect leveling pad! zoom zoom zoom... :drinkup:

McKeeLand
06-21-2007, 10:07 PM
ChampionLS, how does you system work on curved walls? i think that looks like a pretty good idea. coming from a concrete background i always wondered it setting up something more like a form would be better to build the leveling pad.

D Felix
06-21-2007, 11:21 PM
Haven't tried this method on a true retaining wall yet, but it works great for smaller garden walls:

After excavation and base aggregate is in place and compacted, lay down Dee stakes perpindicular to the base. Level the Dee stakes to the proper elevation using a combination of a laser (check the center of the stake) and a 1 foot level. Once all Dee stakes are in place, fill between with sand mixed with Portland (*lean* mix- probably 4-5 shovels of sand mixed with one shovel of Portland), screed off and pull the stakes. Fill the grooves left by the stakes like you would with screed rails on a paver patio. Set your base course carefully! :)

This method eliminates needing flexible forms, not to mention 1/2" PVC is WAY too flexible- any waves in your aggregate will produce waves in the wall. The Portland mixed in with the sand helps to prevent any migration. Just make sure you are using straight Dee stakes!

forestfireguy
06-21-2007, 11:34 PM
Let me start by saying that setting base block is the most time consuming pain in the a** thing ever. So on that note I have heard and not yet being NCMA certified am not sure but anyway, I've been told to never ever no matter what use sand to level SRW blocks, we have used just a little bit of stone dust now and again but sand seems too unstable and easy to shift, just what I've heard and it seems to make sense.

meets1
06-21-2007, 11:57 PM
Setting the base is TIME! Small walls I just trench it, screed and run with it. On a larger wall projects that run a few ft or curve, I form everything up (Concrete guy thing) pamp, add more, re-pamp, laser check, add and pamp again. That way I can run with the starter row.

Yes, if your down in the trench a ways - forming can be tough. I may even leave the back forms in cuz I don't care - wood is old, and it is a temp form at best. That way when I step down, around I can form right to, under or side by side.

My conclusion - it is work either way ya look it! The finish product is what tops off that work!

ChampionLS
06-22-2007, 02:00 AM
Let me start by saying that setting base block is the most time consuming pain in the a** thing ever. So on that note I have heard and not yet being NCMA certified am not sure but anyway, I've been told to never ever no matter what use sand to level SRW blocks, we have used just a little bit of stone dust now and again but sand seems too unstable and easy to shift, just what I've heard and it seems to make sense.

I have used sand before, but I avoid it at all costs. Definitely use stone dust/screenings. Sand are round particles similar to marbles. Stone dust/screenings are coarse angular particles just like bluestone, 2a/2b/57's etc. They hold together and won't wash out. Water is the enemy with a retaining wall. One big rain or flash flood and you can undermine your wall very easily by washing out the sand (even 1/4" can wash out).

D Felix
06-22-2007, 09:37 AM
That's why you add Portland to the sand...

Keep in mind too, that there are variances between individual blocks. Keystone is probably the worst that I've worked with, though I haven't worked with all types. I believe industry standard is +/-1/8", which can lead to 1/4" difference between blocks!! Getting the base level is important, but as long as you are level over 4' (usually spanning 4 blocks), don't sweat the individual blocks if they are rubbing the line between themselves (did that make sense?).

forestfireguy
06-23-2007, 03:32 PM
I just ordered that kalco tool......at 150 bucks it looks like it's worth a shot.