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
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?
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.
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
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
Right off the bat I can assure you your wall will certianly fail with
What is the reason for this wall?
Why 10" thick? We recently did a basement in the Bay Area for a
historic 3 story house and the walls were 10" thick.
I believe if you are not married to concrete use block and step it down
as suggested. The money you will save in materials and labor vs forms
(even renting) will be worth it. If you are a do it yourselfer there
are several different block styles that would allow you to lay them
yourself relativily easily. If you dont want the "block" look simply
put a skim coat of stucco over the block. Compared to 10" thick
concrete using 6" or 8 " block will leave you with money left over.
Dan Deckert wrote:
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.
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.
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.
& adjust your design accordingly
Just for fun humor me and check out the price of block verses what you
are contemplating. There are alot of things yo may not have thought
about. Renting forms: by the time you go get them oil them down buy all
the "additional" ties take them down CLEAN them stack them you can
have the wall built of block and when its done its done. Of course you
would have to "grout" the wall (fill it with concrete) also but trust
me you would still be ahead..ever seen a concrete form blow
out?........ hey I have nothing against formed concrete walls but there
is a time and place and I think if your thinking of money savings (arnt
we all)..well you will see give it a try
Alpha One wrote:
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.
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
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.
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 One wrote:
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.
Use http://www.imageshack.us/ or http://www.flickr.com/ or
http://www.imagehosting.us/index.php 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 (||)
Alpha One wrote:
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