View Full Version : Retaining Wall Question

09-30-2002, 10:40 PM
I am doing a retaining wall for a customer that surrounds half of a pool. The wall is 100 ft long with one 90 degree turn, and three foot high, total sq ft is 300 ft. I am probably going to use the medium sized interlocking block (at lowes etc for $2 a block), or should I use the bigger ones (at lowes etc for $5 a block)? I know the bigger ones are more sturdy, but are alot more expensive to use. I was planning on using small gravel (what size?) underneath the blocks, running black perferated pipe inside the first layer of block for water drainage (surrounding it with gravel as well), and lining the entire wall with dupont landscaping fabric. Any problems so far? It will take 900 medium sized blocks, and will probably cost just over $2000 for materials (block, fabric, pipe, gravel). I need help formulating a total cost for the customer. There will also be backfill needed, but no cutting, this will probably be a separate charge from the wall. Are there any formulas for this??? Should I calculate the estimate from the square footage, what are the going rates? Any help is greatly apreciated.

09-30-2002, 11:27 PM
*On a 3 ft wall like the one you decribed... possibly down the line by using the small block, you could have a collapse in the wall. It is recommended by most manufacturers that geogrid is used in applications of 30'' or more in height, for pinless walls systems. if i used a smaller block on that wall i.e Techo-bloc, I would install geogrid behind it and throughly compact. If I used a larger pin system block i.e Versa, then I wouldn't use geogrid.
* If you havent installed many retaining walls yet, I would suggest a larger pin system block, for it would be easier for you to install and more room for error.
*Pricing I believe without looking at it obviously would be somewhere on a low end of $6000-7000.00 up to a high end of $11,000-12,000.00.


09-30-2002, 11:46 PM
Is there not a wholesale company you can buy them from? We have a block comapny we're lined up with and two nurseries that are able to give them to us for around $1.40 ea. I was just thinking that would give you a larger profit margin.

Brandon Shaw
Evergreen Landscaping Concepts

10-01-2002, 12:58 PM
Thanks for the replies, I will try to contact a block company and see about getting a discount. What is geo grid? Is it expensive? Is it easy to instal? Is it like a fabric? I have heard about it, but do not know what it is. How does everything else look? Any more input on the smaller or larger block? There is about a $500 difference in the medium vs. the large. How deep should I dig the trench? I was thinking 2-3 inches of small gravel (correct?), and bury the first layer atleast half. Keep it coming guys!

10-01-2002, 08:26 PM
Where to begin?

As far as pricing goes, I bid everything per sq/ft. For the most part, I normaly use higher end, or atleast fancier, block than the plain walls. These are alittle more but look so muck nicer. I will normally shoot for $40 bucks per foot, which is ALL the money. If that sounds high to them I will downgrade the block and drop the price to 30. I'm not interested in any walls for less than 30 bucks a foot. The work is hard, and there is lots of it. It might seem to make sense to you to lower your price as a first timer. The troublr with this, is that it is going to take you much longer than an experienced guy. so if your making enough money on the job you won't mind spending the time to fix errors that you would other wise leave.

As for material, I use a very dense stone dust, (not all dust was created equal), that I get from masonary supplier. I buy all my block from them, and they take care of me in discounts, charge account, and speedy free delivery. Well worth cultivating a relationship with a supplier.


10-01-2002, 09:28 PM
As far as gravel to use under your wall look at this thread http://www.lawnsite.com/showthread.php?s=&threadid=3053&highlight=base+stone

This should give you all you need to know on wall base stone and brick paver base.

10-02-2002, 12:50 AM
U had to know someone would pull the seach card sooner or later.....

10-02-2002, 10:38 AM
The thread paul mentioned is a great opne. Better than most mnfr's tech manuals. You've picked a fairly large project for your first one. Take your time and do it right, my two cents on block are go as big as looks okay as block is dependent on static weight for retention.

10-02-2002, 04:22 PM
Problems down the line...........

Smaller wall stone from some manufactures are made for walls under 24" tall some are made to go only 16" high, so it would be nice to know what kind of wall system you are using.

Mow & Snow, I should have understood that there was no way you would have read that thread, It was way too hard for you to fathom :) But some of the newer member here might find that it has a direct bearing on they quality of work that they do. My question to you is what do you call stonedust???

10-02-2002, 06:31 PM
Mow and Snow, I don't want you to feel like I'm piling on, but re: the search - if you type everything you posted here 10-15 times, soon you'll want people to refer to an earlier version of the same stuff you typed. For some of us longer in the tooth here, many of these topics have been discussed in great detail. Referring someone to an old thread just gives someone a chance to benefit from those earlier discussions.

And IMHO, the thread Paul referenced is the best information you'll find on paver and retaining wall base anywhere.

10-02-2002, 07:15 PM
Take it easy boys, I was just kidding. It's not worth getting excited about. I love the search feature, and use it myself. I'm just thinking that most people must have read though a search before posting.

Having said that, I think the way Paul pointed to a thread is a great way to show someone what they need.

As for stone dust, well I don't know how to describe what I mean. There are really two kinds of material that I call dust. One I get from a crushing operation, (Pike), that is very crushed rock. The other is obtained from a masonary supplier. This is the best stuff I have seen. It's very dense and packs very hard.


[QUOTE] Mow & Snow, I should have understood that there was no way you would have read that thread, It was way too hard for you to fathom [/QUOTE

Paul, U know all about dense don't you?] :rolleyes:

10-02-2002, 10:17 PM
Originally posted by Mow&Snow
Where to begin?

As far as pricing goes, I bid everything per sq/ftTom

Doesn't work .... if I have 1000 ft long wall to do that is only one course and a cap high it would have to be priced much more higher than a shorter wall many courses high.

10-02-2002, 10:51 PM
Well we all know that first row is the hardest. The rest are like Lego's. We just need to use our head when it comes to something like that.


10-02-2002, 11:23 PM
Dust as in a very fine powder? If thats what you use for retaining walls, then a few people in your area will be making good money repairing those walls. Just a quick note 50% of the walls installed in the U.S. fail! ( this was a survey done by Rockwood) the time frame on failure is 5-7 years. Leading cause of faliure improper base, followed by improper back fill. Note they did not list if the walls had proper engineering! As for proper stone 3/4"- crusher run stone is the base material of choice among manufacture's and quality installers. Stone dust (all fines nothing larger than 1/4") will not make a proper base.

Now if you mean dense as in not budging on proper installation methods then your right I am, but I will not give poor advice to anyone!

10-02-2002, 11:34 PM
As for a wall 1000 feet long with only one course plus the cap not being able to be bid by the sqft, well of course it works.

1000 ft long x .8 ft high, well that will equal 32,000 dollars.

seems like a fair price to me....


10-03-2002, 07:12 AM
You'd do the 4' by 200 for the same money as .8 x 1,000?

10-03-2002, 09:45 AM
Sure. That still sounds fair to me.

Look, if we think about this on a smaller scale;

20 foot wall .8 high. This will cost what, 70 bucks in material? It'll take one guy half a day at the most to start and finish. That's 540 bucks for half a day. A fair price.

Well, a wall 4 feet by 4 feet while more complex to prepare the base, you've only got 4 of it to do. Again, this job can be done easily in half a day. Material cost is about the same.

The only thing to consider is job complexity. That is some thing we always need to account for....

10-03-2002, 10:43 AM
Maybe that is ok when you are priced at the high end of the market but if you have to compete, then it matters more.

10-03-2002, 07:49 PM
I can see how this would be true. I guess I feel like I've got alot of wiggle room in my price.

What would you consider a high end per foot price?

10-05-2002, 06:08 PM
Are you going to use a crushed base footer?? Do you know how deep and wide it needs to be? You say it is going around a pool. What is the load?? The reason I am asking these ?s is because I am working a job right now that involves a decaying timber wall 10' high and 300' long. The tricky part is, this wall is holding a swimming pool. You can say this is a challenge, anyway. We had to rule a poured wall out, because the footer would have to be enourmous. Block wall is out because there is not enough space to run a grid, so we are back to using ties. Make sure you do your homework as far as structure is concerned. You don't want to put your name on something that is going to collapase in a few years. ;)

10-05-2002, 06:17 PM
Hey if the walls fails in a few years, just peal the magnetic sign off the truck and slap on a new one. Problem solved.

10-05-2002, 06:19 PM
Hey! I was just joking, before you all get upset.

10-05-2002, 06:35 PM
And people wonder why it is hard to get jobs. There are so many contractors out there that do exactly what you said. Not only that there prices are a based on exactly that. To do a job right it costs more. I come across customers all the time that say "Well there price is about 1/2 of what yours is" and you know what I say "Well, when they take the signs of there truck and evaporate call me" So I thank all of you guys out there.:D

10-05-2002, 10:50 PM
ya, I think I'll just "COOSE" a dob I love....

Hey we get those guys here too, they are all over.

10-05-2002, 10:58 PM
Are you using dead men or soldiers? Just wondering since you said the space is limited.

10-06-2002, 09:12 AM
We are using dead men 8', and (or) cribbing.

10-06-2002, 09:25 AM
I'm just wondering about the use of ties Vs block? Normal engineering for a wall like this would be 2/3 of wall height for your grid. Are there problems doing this? 8' ties tell me that you have the room for grid here unless there are other factors that we haven't seen.

10-06-2002, 10:00 AM
My guess is that any type of footer is out of the question. I will have to ask our eng. I know the base of the wall will be near a drainage easement, maybe that is the concern. I would much rather construct a block wall.