I need to have a concrete slab poured to provide a place to anchor a 330
gallon propane tank so it won't float away in the next flood. I live on
a barrier island (Topsail Beach, NC) and we sometimes get flooding
associated with hurricanes... not from storm surge but rather from lots
and lots of rain.
Anyway, I want a 4' by 10' concrete slab poured 8 inches thick for this
tank to be strapped down to. The tank looks like a little submarine.
I've posted an ad on Craiglist and got three replies so far: one is for
a turnkey job for $450, one is for $150 but I have to provide all
materials, and the third never said but left a phone number for me to call.
Using an online concrete calculator shows this should take 1 yard of
poured concrete or 45 bags of 85 lb concrete. I have no idea how much
it would cost to get a yard delivered. I've had some limited experience
with those bags and am confident that is not the way to go.
No matter how the concrete is mixed, it will have to be moved from the
driveway to the back yard using wheelbarrows.
Unless you are planning on doing it yourself, the $ 450 sounds the way to
It is hard for me to say in your area, but not too long ago in NC it was
slightly over $ 100 per yard, but you needed to order about 4 or more yards
or they charged you a large delivery fee. They may still tack on a fuel
I needed about a yard in a hole to support a tower. It was so that the
concrete truck could not get to the hole. I mixed and pored it myself from
the bags. It took 43 bags of the 85 or so pounds to fill that hole. I
rented a mixer and it took about 5 hours to do the job. I did have a source
of water and electricity at the hole.
I think the cost per yard was much more by my method, but I could handle a
bag or so much beter than I could get it from the truck to the hole.
The bid for $450 sounds very reasonable. The $150 bid with you
supplying the materials, and I assume that would include the forming
materials too, sounds a little vague. I would be wary of that bid.
Last year I had a 12' x 14' x 4" pad for a shed poured for $1500. That
included all labor, all forming, a 4" gravel base, 12" wide by 18"
deep footings, all forming, concrete with fiber mesh, all anchor bolts
and nuts, removal of forms and backfilling around slab. All I had to
supply was the drawings.
My inclination is to go with the turnkey bid. I worked with those 85 lb
bags before and it was a major PITA for this old man. I really don't
want to do that sort of work again if I can avoid it.
I wasn't too thrilled with the vagueness of the second bid. I have no
idea what would be required in terms of logistics to get this done.
Like your project, mine is also a moderate distance from where a cement
truck could park.
I guess my main thing is that I don't want to tell somebody his business
when I don't know how to do it myself. That would be the height of
ignorance and arrogance on my part. At the same time, I don't want to
be taken advantage of.
Unless something else comes up soon, I guess I'll call the $450 guy and
tell him he has the job. I've already replied to everybody telling them
I got their emails and was mulling the offers over with a decision to
Thanks for your input; also to Ralph Mowery who also answered. Both of
your contributions have been very helpful.
That's pretty much a given if you're going off three Craigslist
Why don't you open the yellow pages and call a few concrete
You need three bids for the same work to determine who's taking you
for a ride, and who is reasonable. Right now you have three bids for
three entirely different jobs.
Your 330 gallon tank would displace about 2750 lbs of water.
The dimensions you're giving for your slab works out to be about exactly
1 cubic yard of concrete. 1 cubic yard of water would weigh 702 lbs.
So in total you are displacing 2700 + 702 = 3450 lbs, so your slab must
weigh at least that much to acheive neutral boyancy. Since concrete
weighs about 4000 lbs per cubic meter, and your slab works out to be
pretty much exactly 1 cubic meter, your slab would hold down your tank
even if the tank was totally submerged.
Since you don't need anything fancy in your concrete mix (like extra
strength, fiber, pigment, etc) you're looking at the cheapest concrete.
Maybe a few rebars thrown in.
Concrete normally costs about $150 per cubic yard - delivered, and some
small cement trucks would have no problem with a minimum 1-yard
Any idea how far away the closest batch-plant is from you?
Is the location for this slab easy to get to from the road? Will the
soil conditions support a cement truck getting close to where you are
putting the slab?
Who-ever gave you the $150 just wants to back a truck up to your forms
and pour the concrete down the chute. For $300 someone is going to lay
out about $20 worth of lumber and stake it in the ground to create your
forms and then pour $150 worth of concrete in it.
Is this going to be above ground - or is someone going to have to dig a
hole for this slab?
There is one about 10 miles from here. I'm planning to call them in the
morning to find out about my options.
I have a marl driveway. I don't know whether it can support the weight
of a truck or not. I've never had a problem with trucks before but I've
never had a concrete truck come before either. Out on the street:
absolutely no problem.
If it can back into my driveway, the closest it can get to the slab site
would probably be around 75' or so. The side yard has a septic field in
it so I won't allow any vehicles on it. Wheelbarrows are OK.
My engineer buddy suggested that we dig a groove down both long sides.
That will create an inground lip which should prevent any rocking from
occurring. I would expect this slab to be both in and above the ground;
maybe half and half?
Sounds reasonable to me. I'd find out exactly what they have in mind
as far as setting up the pour, any digging, stone base, reinforcement
rebar or wire.
It is not a complex job at all, but it is heavy material and a lot of
labor. Personally, I'd want a lot more than $150 to do it.
You have to provide all the materials as in: You have to go buy (and pick
up) the form lumber, rebar, and concrete, or you just have to pay for it,
and he will go get it? (I'm ass-u-ming the concrete will be delivered.)
There is a big difference. PLUS, if you pay for it, you keep the forms
afterward, and you can use the lumber for other forms in the future, or on
Where I live, one can go get a mixer that has up to three yards of concrete
in it. When you pick it up, they add the water. You have XXX minutes/hours
to pour it........... enough time to do it, IF YOU HAVE IT FORMED OUT AND
READY. You clean the mixer and bring it back for your deposit. Cuts the
cost way down for small pours like this one. Maybe there is one near you.
You can go get the mud, or give the guy an extra XX bucks to do it, but when
you pay for it, they can't mark it up.
$450 sounds really good if he will make the forms, prep/pack the
ground, lay some rebar, mark the level, bring the concrete,
wheelbarrow it around, level and smooth it, clean up and return the
I filled some footers recently that took 2 yards of concrete. We
picked up a couple concrete carts at rental works. They hold a yard
and cost about $250. See the Cart-A-way picture here
http://rentalworksofmd.com /. I can't recall how many wheelbarrow runs
it took, but we had 2 or three going non-stop. Don't forget to add
some rebar in there.
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