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View Full Version : Retaining wall questions (1st wall)


JLC
07-30-2007, 12:27 AM
First off, sorry for the long post. I own a lawncare company and for several reasons we are doing a couple of feaseability studies to determine whether or not to enter the landscape/hardscape market. In regards to retaining walls my business partner and I have done a lot of research over the last couple years on them. We've attended multiple classes from our Keystone rep and are familier with theirs and the NMCA standards.

We have lined up a trial job to help us put our knowledge to practice and get a feel for the work before making a large commitment going into next season. The job is for a family member replacing two rr tie walls. One is 80 feet long and mostly 3 feet tall. The other is 30 feet tall and 3 feet tall at it's highest portion (about 10 feet of it). We did the 30 foot wall first and did it "by the book". The area we struggled with was setting the base course of block on our leveling pad. Our leveling pad was on average within an 1/8 to a 1/4 of level according to the laser. Most of the blocks laid without having to do much more than smack them a couple of times with a deadblow, but some seemed to take what felt like 10 minutes to set each. In the end the wall is complete and is level and done right, however...

Before starting the 80 foot run I was wondering if this time to set the first course is normal or do you experienced guys think we should try to get the grade better/dead on. I've heard of guys through my supplier who use 1/2" of screeded lime fines (3/8 or smaller) to give some room to smack the blocks perfect, but didn't know if this would cause problems down the road. This seems to be a grey area as to whether it is acceptable or not. We are trying to nail down somewhat of a system to build our confidence going into next season, should be decide go ahead with this.

Enough rambling and thanks for any advice/ help in advance.

Ben

JLC
07-30-2007, 12:56 AM
I also wanted to mention, my hats off to you guys doing this day in day out. It's hard work, and my partner and I are strong guys.

waltero
07-30-2007, 12:57 AM
I try to get the grade on the base to be almost perfect. I do it by using rails on both sides (front and back) of the wall. I use concrete forms that are flexible to allow me to do bends and curves. If you go to Versa-loks website you can see a video that shows the forms being used. It takes a little longer but I try to get the base as close as possible and I only use a very small amount of sand when I need it. I believe that you can go up to 1/2 inch on the sand but I would try to get the base closer to level so that you wouldn't need that much.

You will find that this takes the most time.


http://www.versa-lok.com/contractor/cInstallationr.htm

PerfiCut L&L
07-30-2007, 10:41 AM
JLC: As is with most hardscape projects, the prep is the most important and most time consuming portion of the project. With retaining walls, your first course is more or less considered prep for the rest of the wall. Think of your first course as an extension of the sub base. If its not done correctly, you're going to see it in the wall exponentially based on the number of courses you go.

So to answer your questions. YES. The first course is very time consuming. It does take some one on one time with each stone to make sure they are level, left to right, and front to back.

Unfortunately, theres no tricks, or magic mallet that will make this step go quickly. Only time, experience. Good luck with your future endeavor in hardscaping. Look forward to seeing some of your work.

forestfireguy
07-30-2007, 01:02 PM
Welcome to SRW walls, base course are miserable. There is a toll out there that we just bought, save loads of time, it's a mini-screed, kinda. You set your first block. The set the screed thingy off that first block, then screed as you go......

Mike33
07-30-2007, 05:40 PM
I feel the way you did was just fine. We level with laser until a step area if needed, than level block for block. There will different opinions here such as forms and etc. The bottom line is level is level the method you choose dont matter as long as you get them level and feel comforable. Good luck to you and i think your the first to ask a reasonable ? with out asking what to charge.
mike

JLC
07-30-2007, 06:43 PM
Yeah, I've read a lot of posts about the how much to charge and stuff like that...I can figure that out...I don't think the forum needs another one of those questions lol. Seriously though, thanks for the constructive input on my first hardscape question, I'm sure I'll have more, and then will hopefully be able to return the favor to someone in my shoes down the road.

I watched the videos in the link posted by Waltero. In one of the videos, versa-lok allowed the use of a thin bed of sand to aid the leveling process. That surprised me because I'd think if you did this you'd want something like lime (about the consistancy of sand, but angular) as I'd think it would stay put better than sand. Do you think this would be OK, or does it open a can of worms?

Ben

B. L. Landscaping
07-30-2007, 08:17 PM
I would have to agree with forestfireguy that the mini screed or stone screed google it and you will find it saves alot of time. Get your base as close as possible, set first block set screed and put a minimal amount of sand to level each block there after this tool works very well.

Mike33
07-30-2007, 08:34 PM
Im old school stubborn to change at times. I level with the stone no sand or dust. The guys using forms and screeds thats great i respect there way they are giving 100% to perfect there product.
Mike

ChampionLS
07-31-2007, 01:45 AM
If room permits, you can simply rake out a berm of QP (2a Modified Stone), compact it, and then use screed rails (1/2" gas pipe or EMT Conduit) to set the leveling pad. We use a laser to level the pipes and top it off with Screenings. You can then simply place your blocks anywhere on the pad and not have to do a thing!. Very fast.

If your in a tight area, or need to make curves, we frame the entire wall leveling pad with either cheap wood, or Luan strips to make curves. We'll fill in 95% of it with QP, and tamp. The final amount is Screenings that is screeded along the forms. After the base block is laid, we remove the forms and backfill as the site requires. Well worth the time.

Another note:
I do not believe in leveling "each block" as you go along. That is not leveling. Just because one block is level next to another does not mean they are all at the same elevation. The wall will be wavy, and it worsens as you go up! Take the extra time and build a leveling pad.

forestfireguy
07-31-2007, 08:08 AM
Eveningstar,

Not to be arguementative but I'd guess the majority of guys building walls are leveling each block, level a block 4 ways and check heights with a laser, how is it that it's gonna be wavy if you're the same on each one?????

forestfireguy
07-31-2007, 08:28 AM
After a little further thought, I wonder if over time you will save time doing it Eveningstars way, I'd guess once you really become proficient at setting base like that it goes reasonably fast. I wonder though about the screenings, how thick are we talking about, have you ever had issues with the wall "rolling" on the uncompacted material?????

D Felix
07-31-2007, 07:35 PM
I've use the "Stone Screed" tool from Kalco (we have one), but I don't think we'll use it much any more. If you aren't carefull, your wall base will slope up or down depending on how you have the screed end set....

I've posted this before, but for garden-type walls, we will get the base very close, but 3/4" or so low. We will then lay down straight Dee stakes perpendicular to the base, leveling each one with a combination of the laser and a 1 foot level and hammer. Laser in the center to get it at the appropriate elevation, level end to end. Once there are enough Dee stakes in place, a very lean sand/portland mix will be put in between and screeded off like you do with a patio. The portland is added to keep the sand from migrating. Once everything is screeded off and the Dee stakes are pulled and the stake grooves floated off, you simply set each base block in place.

Have yet to use this method on a true retaining wall, but I don't see why it wouldn't work, especially if the portland is added and crushed gravel (not clean) is used in front and behind the base blocks to key them in.

And, yes, this way is a LOT faster- we set 30 feet of base earlier this spring in less than an hour from the time we dropped the first Dee stake....

zedosix
07-31-2007, 09:32 PM
I set my screed rails on compacted level granular A, I then screed a small amount of stone dust and lay the base course near as fast as the second and third and so on. I really don't know why you guys are levelling one by one. Man there IS an easier way.

Mike33
07-31-2007, 11:02 PM
If room permits, you can simply rake out a berm of QP (2a Modified Stone), compact it, and then use screed rails (1/2" gas pipe or EMT Conduit) to set the leveling pad. We use a laser to level the pipes and top it off with Screenings. You can then simply place your blocks anywhere on the pad and not have to do a thing!. Very fast.

If your in a tight area, or need to make curves, we frame the entire wall leveling pad with either cheap wood, or Luan strips to make curves. We'll fill in 95% of it with QP, and tamp. The final amount is Screenings that is screeded along the forms. After the base block is laid, we remove the forms and backfill as the site requires. Well worth the time.

Another note:
I do not believe in leveling "each block" as you go along. That is not leveling. Just because one block is level next to another does not mean they are all at the same elevation. The wall will be wavy, and it worsens as you go up! Take the extra time and build a leveling pad.
Good point, however i think what you are saying if you didnt set a level base and just started leveling block to 1 another it would be wavy, I agree. What i was saying i sit my base with laser and check every ' or so then i start leveling every block and most of time its add a stone or a good blow with hammer.
Mike

JLC
07-31-2007, 11:24 PM
Thanks guys for the posts. Alot of good information here. Interesting to see the different methods and what works for different people. To update my progress, I just finished working on the wall for the night. Got my leveling pad in for the first 30 or so feet of the bottom wall. This takes me to my first step up of 3 on this longer wall. I got the base much closer along the run of the trench. As I laid the block though I was off a little perpendicular to the trench. Not by much, but enough to make me unpleasant to be around for about an hour lol. I haven't used it yet, but I also took our dump to the quarry and got some limestone screenings. Its consistancy is very close to course sand, but it is angular. I may try it on the next step up tomorrow and see if it helps. D Felix, I like your idea for leveling the trench perpendicularly and may try that tomorrow too. I've got about 50-60 more feet to try some different things. I'll post some pictures once I have something presentable too.

ChampionLS
08-02-2007, 01:29 PM
I think you guys got the point. It's definitely easier to make a leveling pad first, and then lay the blocks all at once. The one-by-one method is for the weekend do-it yourselfer who has access to limited tools and can spend hours tinkering.

With the leveling pad method, it's best to top it off with screenings/stone dust- just enough to cover the coarse aggregate and establish level. (about 3/8") I would not use, or recommend sand, because sand can very easily wash out and allow the entire wall to shift. Don't forget, a retaining wall must handle water and drainage. Screenings/stone dust will stay put under the block.

Check out this leveling pad. A quick mix of concrete with simple forms. They lay the wall block right on it. Nice and simple! While it's overkill for your basic hardscape, it works just the same.

Champ

Humble Earth Mover
08-02-2007, 02:48 PM
I was taught to install a base of tamped and leveled modified 6-8" and then to set the base course in a mortar bed right on top of the modified, leveled side to side and front to back. (Except for steps which of course pitch forward) Sort of like laying CMU block. The guy who taught me has been installing this way for over 10 years and has never had a wall fail. I'm not saying this way is better, but it does work.

JLC
08-02-2007, 04:13 PM
Hindsight is always 20/20...I wish I would have done more overdig and used forms to make my leveling pad with on the longer wall and then screeded lime screenings over the last 3/8 to 1/2". In the end the block would have laid in easier and much faster. I think the margins dollar wise would be much nicer that way and the frustration factor would be less. I've also found on some of the blocks I've fought that they were off on thickness compared to the other blocks.

zedosix
08-02-2007, 05:32 PM
Hindsight is always 20/20...I wish I would have done more overdig and used forms to make my leveling pad with on the longer wall and then screeded lime screenings over the last 3/8 to 1/2". In the end the block would have laid in easier and much faster. I think the margins dollar wise would be much nicer that way and the frustration factor would be less. I've also found on some of the blocks I've fought that they were off on thickness compared to the other blocks.

Yes they can be of different thickness, the molds get warn out and voila different sized brick. Same goes for the paving stones. Not usually the thickness but the length and width can be off by as much as 3/8".

AztlanLC
08-05-2007, 05:08 AM
Just like someone mentioned before we mix 1 part portland cement 4 parts sand or stone dust and spread dry 1/8"-1/4" then we use a 4' level and screed, it's being the fastest method we have found so far.