Can I cast my own concrete retaining wall?

I shouldn't do so as others have already rained on your plans but some things need to be said even stronger than have been.

No, you cannot just use your local sand. It is dirty no matter how pretty it looks. Dirty sand makes for weak (or no) concrete.

Standard mix is 1 part cement, 2 parts sand, 3 parts agregate (or is it the other way around. Been a long time since I mixed from scratch.

You will almost certainly need a permit. They will not issue one without a plan showing what the footing is, width/height of wall, placement of re-bar, etc. You haven't shown that you have any concept of retainer wall design, that is so basic to the project that without that the wall will fail just from the weight of the sand behind it.

Even if you were to take time off work you will not hand-mix that amount of concrete in any reasonable amouint of time even using a mixer.

You say a truck can't get back there. Well, every pound of cement, gravel, sand will have to gotten back there somehow. Pre-mix can pump the mud back there with no problem. You could build the forms yourself or have them built (a whold field of knowledge in itself) and buy pre-mix - probably find that the cost of the concrete in place would exceed by much your cost of mixing it yourself.

Don't worry about the delivery cost of purchased blocks. It will probably run in the 2-3 dollar/mile range (last time I had it done it was on $1 per mile), very minor add on to the a truckload order.

Harry K

Reply to
Harry K
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way betrter to slope the yard.

Walls ALWAYS FAIL! No mater how well constructed one day you will be rebuilding.

Reply to
hallerb

No problem, I appreciate all the input.

And someone else said that salt does the same, so that probably kills the whole idea right there. The main motivation for this was that I had the sand already.

Think of my post as a trial balloon. Since we are strangers, you will just have to take my word for it that I wouldn't begin the actual wall without learning a lot more than I know now.

I was actually planning on taking an unreasonable amount of time. Another person thought that an unfinished wall over a long period would cause problems with the neighbors, but I don't see why it would be that unsightly if I was doing one layer at a time. At worst, the entire length would have only one block difference in height.

OK.

Either you left a word or two out, or I don't have a clue what you are talking about (or both). Can you restate that paragraph?

A lot of places have jacked their delivery charges up since the gas prices went up, but I'll check it out. Thanks.

Reply to
Tony Sinclair

You want a 100' long retaining wall, 4' above ground, 2' to the footing, with a 2' wide footing say 8" thick, and the wall itself about 8" thick, so you're looking at 8" x 8' x 100 = 534 cubic feet of cement. If a bag is about 1/2 cubic foot, then you're looking order-of-magnitude, 1000 bags of ready-mix.

If you're making your own concrete out of local materials (which you shouldn't do), then the concrete is only around 15% by volume of the ultimate wall, so you only need around

160 bags of cement.

What's a bag of cement cost you, retail? Somewhere around $9.00?

How does that compare with the price of having some guy in a truck drive out to where you are, and shovel directly into a form that he set up the weekend before?

Doing large-scale concrete work yourself is almost never cost effective. Your sweat equity isn't anywhere near enough to make up for the lack of heavy equipment.

Reply to
Goedjn

That gets you mortar, not concrete. You need aggregate too for concrete.

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Reply to
dadiOH

What kind of sand? Sharp or not? Size? Clean? How wet is it? Got salt in it?

All are things that affect how useable it is.

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Reply to
dadiOH

It's all a matter of being cooperative. If you're already on great terms with your neighbors they might not mind the on-going project. Heck, they might even throw in some labor to help speed it along. But think about it from their perspective. Looking out and seeing some on-going construction effort tends to get a little annoying. Some folks tolarate it more than others. It's one thing to have a garden or something being tended to over time. It's another thing to have an open trench, a lot of sand piled back away from the work, worn pathways and construction debris littering the view for months on end. If you have the choice of being nice to your neighbors it's always worth considering.

But for a 100' foot it really shouldn't take all that long if you're using prefab blocks. Rent a backhoe/loader (from sunset or someone like them) for a weekend and clear out where the foundation needs to go. Along with pulling back the sand to allow the work. Backhoes are actually not that hard to operate. Something like a small TerraMite with a backhoe and a loader is pretty simple and would do the job. Form it up, have concrete poured and let it dry. That part of the work should take about 3-4 days along with a week or so to let the concrete dry. Then spend the next week laying the blocks and get a Bobcat to push the sand back up against it.

Once you've got a good base it's REALLY easy to plunk down the blocks and get a wall built in no time. Be sure to have someone around to help massage that sore back!

Is it because you think the ground won't support it or that there's physically no way to fit a truck in there?

Depending on local code and conditions there might be alternatives to using a poured foundation. But you'd have to ask the local building inspector's office.

It's always a good idea to shop around and do some haggling. This should be a slow time of the year 'round there so there ought to be someone hungry for the work...

-Bill Kearney

Reply to
Bill Kearney

You're right. it should have read "would NOT exceed by much the cost of doing it yourself" By the time you have a mountain of sand, aggregate and a pallet of cement hauled in, the costs have started to add up before you mix the first shovel full.

There was a good suggestion made by someone. Get a standard bag of premix, make up a cobbled together mortar tub (couple boards and piece of flashing or just use a wheelbarrow) and mix it to specifications using a common garden hoe. Now look at it and see just how much work that was to mix up just 2/3 of a cubic foot - that is the amount in the common size bag. The work is some less but still hard even using a mixer. It is a valuable bit of practice as you will no doubt be wanting small quantities of concrete around your place in the future for other tasks. Good to know what it is like before you go into a project.

Harry K

Reply to
Harry K

if you need 5 yards or more its way cheaper to have it delivered all ready mixed. although you will need help laying and finishing fast.

last ime i need a slab my neighbor needed a sidewalk, we worked together to meet the 5 yard minimum.

i kinda inherited a cement mixer but woulds still prefer pre mix

Reply to
hallerb

According to Tony Sinclair :

As others have mentioned:

100' of retention wall up to 4' high is a pretty massive undertaking.

Doing it a couple blocks at a time without proper design from somehow who knows what they're doing just isn't going to work. It'll probably fall over long before you complete it.

Your cheapest bet in terms of concrete is probably a poured concrete wall rather than blocks.

4' of sand, especially where at least 2' of it is freshly disturbed, _will_ push the wall over without careful attention to footings, reinforcement and drainage control, regardless of whether you get freeze-thaw.

You're best off getting an engineer to design the wall first, and ensure that you can get a permit for it.

Once you have an approved design, you can figure out what parts you can do yourself, and what you need help for.

If you can do the forms (and probably rebar) yourself, then just bring in the pre-mix trucks to fill it.

The biggest difficulty in doing it yourself (aside from exhaustion) is the cost of material in the forms. It's quite possible you can find a concrete contractor who has pre-made re-useable forms. In which case, you're just renting them for a few days.

It may be possible to pour it in sections if you can reuse the forms.

You are _definately_ going to need professional assistance on this.

Reply to
Chris Lewis

Seems to me you're paying delivery charges for everything, including the stuff they deliver only as far as the store you buy it at. If the store is 10 minutes away and the supplier is an hour away, the supplier is at least 50 minutes from the store. Unloading might be a little cheaper at the store, because they have a forklift, but to buy it from the store, you'll have to load it a second time, and unload it a second time at your house.

I know that this is not perfect, because you plan to only buy the raw ingredients, which are sold from a different place than pre-made blocks, but it seems to me it would all add up the same way.

This is NOT a recommendation to buy from the manufacturer an hour away, only an effort to challenge your idea that shipping would be more. It might well seem more because it would be itemized, but the stuff at your local store doesn't ship itself for free, and it doesn't hitchhike. If the place an hour away had to send a whole 2 two-ton truck to carry 5 pounds for you, that would cost you a lot, but it sounds like you need a whole truck load or whatever you need.

You have to look at total price, including how long it's going to take you. If you make 20 dollars an hour at your job, maybe you shouldn't figure 20 for your spare time, but at least 1 or 2 dollars an hour for your spare time. Unless you plan to enjoy this so much that it will replace *spending* money on recreation, and I think you might for the first day, but it will take longer than that. There is also the pride of doing things from scratch. You have to consider all that. Sadly, I doubt many people will be very impressed that you mixed your own concrete.

Is that true guys?

It would just be something you are prooud of, and they are slightly impressed by.

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Reply to
mm

Your can't use sand just shoveled off the ground. It needs to be washed of any organic material. Concrete is sand and stone so you will also need stone to add to the Portland. This is a big waste of time and energy. If you are going to try to mix yourself than buy 80lb premixed bags. One bag does 2/3cu ft. You have over 8 yards (216 cu ft) so that's, lets see, 324 bags. I suggest you go get 1 bag put it in your wheel barrow and mix it up. Now do you want to do another 321bags?? And will you be able to mix them all the same so the finished product will have uniformed look? If you still want a concrete wall get a redimix truck and 4 guys with wheel barrows . Park the truck at the curb and wheel it in one wheel barrow at a time. best strength and look is to do this as a continuous pour. This, of course, is after you have poured a footing, at least twice as wide as the wall on top of it. And you have all your forms in, tied together, and braced real well. If you want a cheap masonry wall then pour a footing and dry stack standard

8x16 block. Fill the block with concrete. You can do this a section at a time. Still need lots of material. For sure a mixer. IMO best looking and easiest masonry wall is the precast, interlocking blocks. Just a peastone/dust footing and then stack them up. Many will do more than 4'.
Reply to
calhoun

That's a situation I'm in, and I'm hoping to start my own thread on questions unique to me. That's why I'm reading your thread so closely.

I think they have 50 foot chutes (I've seen them pour foundations for the new style of garden apartments, but I just estimated the length), but I don't know about 100. Does your planned wall start at the street?

Some have like a big self-powered wheelbarrow. I haven't seen one yet, but I'm told it carries as much as 3 normal wheel barrows. I guess it has it's own gasoline engine, and maybe treads?

Do they tip so that the concrete goes right into the hole for the footing, or do they need to use shovels?

I actually went to a place that has this all last Friday, but the guy she said I wanted wasn't in, and I didn't learn anything.

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Reply to
mm

There are often, iiuc, regulations regarding coastal dunes, also.

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Reply to
mm

I'm trying to remember where there is one I see regularly that is leaning 10 degrees now. I wonder how long, decades? until it falls over.

I used to think that tombstones just sat on the ground, but apparenly they have a footer that goes ??? how far into the ground. I don't want to guess wrong, and I'm not sure now what I was told. I think there is a cemetery near here, where they have one footer for a whole row of tombstones, 40 feet long. Maybe since it's one piece, it doesn't have to be as deep as a 3 foot long footer would have to be.

Do many cemeteries just use footers as long as the tombstone is wide? Because it is only at this one cemetery where I can see the part between the graves, and even at this place in the older rows, the dirt and grass has spread over the footing and I think you can't see the part between two stones.

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Reply to
mm

According to mm :

There are concrete pumper trucks that can push it hundreds of feet.

This is probably the least of his worries.

Reply to
Chris Lewis

According to mm :

It might be. It may be a lot less than that.

I've seen brick/concrete pillars fall over on perfectly level ground within 2-3 years. They didn't have footings, and didn't have any lateral pressure except wind on the fencing they were trying to hold up.

Some may well have footers. But there's rather a large difference between a smallish free-standing tombstone only having to worry about a bit of wind, and one 4' high, 100' long, trying to hold back unknown tons worth of wet sand on one side doing its damndest to push it over.

You're _way_ over your head if your understanding is at this level.

Start here:

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Pay close attention to the stuff on drainage etc.

Reply to
Chris Lewis

I'm glad to hear it.

My problem is that it has to go around two corners, to get behind my house. Do these trucks do that also?

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Reply to
mm

Of course. I wasn't trying to understand retaining walls in these terms. I guess I was changing the sujbect and trying to learn about tombstones, if anyone here knows more about what is underneath them, and if it's common or not to have one long footer for 10 or 15 stones.

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Reply to
mm

yes. they typically go up and over, not along the ground. think long boom trucks.

Reply to
Charles Spitzer

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