Building a concrete wall question

[Alpha One]

I want to build a concrete wall that is 56.5 ft long and 4 ft high from the top of the wall to the bottom of the trench, that is, total height including the footing. The wall will be 10 in wide and the footing will be 20 in wide by 8 in. (or 10) deep. It will take 7.5 yards for both the wall and footing. The footing alone will take about 2 yards. If they bring 7 yards will be chipper that if I order 2 plus 5. Then, I would have to pour footing and wall at the same time. Would the concrete stay in the forms up to a height of 4 ft? Or would if flow out through the bottom? Also, since the wall slopes by 3.5 ft over 56 ft, will the concrete run to the lower side?

Than you

[Glenn]

A 10" thick wall seems a little heavy but I assume you have your reasons. Pour the footing the day before forming the wall and I would use (hire or rent) metal forms with regular form ties. That would not only be easier, but cheaper than all the form lumber it would take. Put the footing deep enough to allow you to use 4 foot forms and of course pour them full to screed off the top. I would use 24" wide footings. If this is a retaining wall and it sounds like it could be, I would go with at least 36 inch wide footings. With your questions, I can see a disaster if you don't use this method. Three feet of fall in 56 feet will be manageable though I would use a slight slump, ie fairly dry. I assume you plan on using steel rebar too.

[Jonny]

Works out to .75" per foot fall/rise. That's steep enough for guaranteed drainage leaving solids behind the wake.

Consider stairstepping every 10'. Depending on the soil content and how deep you go, the footing may walk.

Pour the footing first. Leaving some rebar exposed to tie it to the wall above it.

[Nehmo Sergheyev]

Learn a bit about concrete; then re-plan the job. You seem to be planning a retaining wall to retain a sloping grade, probably on the side of a residential lot. The first step is to accurately survey the site. Determine where you want the wall. If you want it on your side of the property line, determine where the line is. Then using a water level, figure out exactly how much difference there is in height from one end of the line to the other. Then, find out how low frost footings are supposed to be in your area. --- That's enough for now. Report back.

[Dan Deckert]

I'd have to believe your footers are undersized. Dan

[Italian]

[mcse3456]

I agree with others; you haven't said what the wall's purpose is or what the conditions are on the site.

If this is a retaining wall, it is low enough to not be too hard to do if you get enough footing under it. I also agree yours sounds undersized and your wall thickness sounds like too much.

If it's a retaining wall, what type of soil will it hold? Is it expansive, like clay, when it's wet?

Is there any chance that you will have water build up (pressure) behind it? If so, have you planned for drainage?

How much dirt is behind the wall in the sense of slope? Is there a steep slope rising behind it, or is it level ground?

Will there be any unusual loads placed above the wall, such as a road or driveway or a nearby swimming pool above it?

Does your climate present a frost heavy issue?

In our area, walls that are 4' or less don't require an engineer, but that doesn't mean they aren't a good investment especially if you don't know too much yourself. We don't have deep frosts, so engineering for that isn't an issue. You can google retaining wall and retaining wall drainage and learn a lot really quick.

Now, if this is just a decorative wall for a screen of some sort, everything changes except for my $.02 your footing and wall thicknesses still seem out of whack.

[Alpha One]

The wall will be a retaining wall in my backyard. I intend to use three 3/4 in. rebars orizontaly and vertical ones spaced 2 ft or so apart, plus two

3/4 in. rebars in the footing. Nothing will be on the top of the wall. The soil underneath on one side is rock for a distance of about 25 ft at a dept of about .75 to 1 ft, and the other 31 ft is soil never moved. The footing will be 24 in. wide, maybe more, by 12 in. deep. The dirt behind the wall is dry and will be about 5 in. below the top od the wall and it goes flat from there. There is no drive way or anything else on it, just grass. I intend to use gravel and a pipe plus cloth for drainage. The wall's hight over the rocky side will be about 3.5 ft. (from the rock to the top of the wall). The rest of the wall, starting right after the rock will be 4.5 ft. from the bottom of the footing to the top of the wall and at the other end will be 3 ft, also from the bottom of the footing to the top of the wall.

[Bobk207]

Your design is "somewhat" close but IMO #6 bars are way too big & the distribution needs a little work. Footing needs to be wider & needs to have some distributed rebar in it.

checkout

& adjust your design accordingly

cheers Bob

[Italian]

[Alpha One]

Three years ago I built a concrete retaining wall in the same backyard 10" wide, 5.5 ft high and about 44' long. Plus the footing which was 3' wide by

1.5' high. When I was finished I had spent $2,500.00 or more. This included concrete, steel, wood for the case, etc. If I had done it with blocks it would be much cheaper, but also less strong. Because it is in a L shape one side keeps the other from tipping. On each end the dirt goes up to the top on the outside also. So, it should stay in place for quite some time.

[Nehmo Sergheyev]

That's low, even for just the materials. And do you mean forms by the word "case"?

-- (||) Nehmo (||)

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Alpha > Three years ago I built a concrete retaining wall in the same backyard 10"

[Alpha One]

More accurately:

Today I measure the wall and checked the receipts. The wall is 51' long. 34' has a footing of 3' by 1.5' and a wall of 10" by 5.5'. On one side 17' are only almost 2' high by 10" and no footing; it sits on top of a wall previously there. I ordered a total of 12.5 yards at $75.00 was $993.75. With rebars, wood for forms (case) etc. I spent $2,784.00. This is for all the materials including any tool I had to purchase because of the wall.

[Nehmo Sergheyev]

How did you dig the hole? And how did you make the forms? You made forms 5.5 feet high? I'm not saying you didn't do it, but that's something of an accomplishment for one guy and $3K. You didn't mention paying any labor, so I assume you did the whole thing by yourself.

-- (||) Nehmo (||)

----------------------------------------------------------------- Alpha > More accurately:

[Alpha One]

By pick and shovel. Took a while and lots of dirt moved. From begining to end it was just myself. The forms I did with 2x4s and 3/4 plywood. I tried to send a picture as an attachment but it didn't go though. If you go to alt.binaries.photos and look for 'For Nehmo' you can see the wall form different angles.

[Nehmo Sergheyev]

Use

or or or if you want a ng, news:alt.binaries.photography . My newsserver doesn't carry the ng you used. The photo hosting sites will hold the pics much longer, but there's a size limit.

-- (||) Nehmo (||)

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Alpha > By pick and shovel. Took a while and lots of dirt moved. From begining to