Hi, I'm an owner/builder about to hire my first concrete pumper to pour my footing. (It's a heavily wooded lot so a ready mix chute won't reach.) There is precious little on the internet about this.
I really don't know what to expect. Would some of you more experienced contractors care to comment?
My job in brief: 22 cubic yards, 3000 psi, vert rebar (with safety caps) every 16", wooden forms, water available, engineered (stamped) drawings, western NC.
My questions run the gamut:
1) How do they normally charge? What are rates like in your state?
2) Is "wash out" ever a problem?
3) Who orders the mix, me or them?
4) Will the mix need vibrating?
5) Should I allow the pumper to adjust the mix?
6) The tradesmen are fairly honest out here, but what to watch out for?
7) What are the questions I forgot the ask? ;)
I just want to be informed before I start asking for estimates.
Morning pumps cost more than afternoons. Ground pumps cost less than aerial pumps.
Washing out the pump? Not any more so than the concrete trucks, but you will certainly need a place for the initial slime and the hose and pump clean up.
Who is paying the bill? If you order, make sure you tell the batch plant that you are pouring with xyz pumping company and you will need pump mix. If there are any questions, let the pumper work out the details.
Yes
Insist on desired slump. Discuss before contract. Write into contract. Defer to the pumper's expertise.
It's probably too late now, but we had a similar situation when we built our house. Our house is surrounded by trees on two sides, a garage on another, and our septic system on the fourth. The only access was from one corner of the building site.
I considered hiring a pumper, but was concerned the trucks wouldn't be able to navigate down our driveway to the building site. Not to mention the added expense.
So, I poured our foundation in four stages: Rear footings first, then the rear walls, front footings, and then the front walls. This allowed the truck to back right up to the forms for each pour, and it also allowed us to reuse the forms so we only needed half the form materials. It also meant we could do each section with a single truck load, so no problems trying to coordinate multiple trucks coming and going out our drive.
I extended rebar a few feet from the first pours, so the second pour would tie into the first. I expected cracks to form where the sections joined, but we've lived in our house about 4 years now, and there still aren't any signs of cracking at the joints.
We used a company with a truck that mixed the concrete right on site. No waste, and he was able to supply extra if I undercalculated a little. We got exactly what we needed, and only paid for the concrete we used.
It was still kind of wet and muddy around here when we poured the rear footings, so the driver didn't want to back his truck in too far and get stuck. So, we had to wheelbarrow a few loads to the back corner. But it wasn't too bad.
Things had dried out by the time we got to the rear walls, and I had put a layer of gravel in the crawlspace area too, so he was able to back right in. There was only a few feet in the back corner he couldn't reach (because of interior footings), but we were able to paddle it into the corner without difficulties.
Our foundation is just a crawlspace, so we simply used boards to work the air bubbles out of the concrete, especially around foundation vents and other obstructions. It worked out very nice. I think I only had one small void at the bottom of one of the walls, that was easily patched after I stripped the forms.
It was just my wife and I doing the work, with a bit of help from the concrete driver (don't expect help from them. :) ). We repaid his help by giving him lots of repeat business over the years, doing the foundations, sidewalks, etc.
There is a base charge, then either an hourly charge or charge by cubic yard pumped. Rates depend upon whether you are getting a line pump or an overhead boom pump. Rates vary too much to be of use. Call a pump company and ask.
What do you mean by wash out? If you mean blow out, then yes, it can be a problem if the forms aren't braced well enough to hold the concrete or if you pump too much in the wrong place at the wrong time.
You do. You must discuss with your pump company what they require in order to pump your ready mix. Then order the concrete and tell them it is for your pump company.
Not if the forms are less than a foot deep. Anything over that and you will probably need to vibrate.
Only under your supervision.
Bad concrete mix, incorrect concrete mix, adding water, concrete too old, etc.
When you decide on a pump company, have the rep come to your site to determine the size of the pump needed, where to locate it, where to clean out, where to position trucks, etc.
You are not going to get estimates. You are going to get rates. They are all pretty much the same unless you are pouring more than 500 yards a month, then you can make some deals.
You might try to find someone that is experienced in this sort of thing to oversee the pour for you. It can save alot of heartaches and wasted money.
May sound trivial or unnecessary but be sure you have ample width for the pumper to anchor and extend his outriggers (level, ~ 40' x 60' or so). I invested an extra 2 hours of highlift time to prep the site besides the $125.00 / hour for the pumper (4 hr min, yard to yard time).
You asked for comments from experienced contractors.
I am a second generation builder that has been building since 1996. I also have helped 50+ owner/builders construct their homes.
The rates vary depending on the type of pump. Around here (Birmingham, AL - probably similar costs in NC), a modest boom pump will run 5-5 per hour. They typically have a 4 hour minimum + 1 hour travel time. I expect you'll pour 22 yards within that time frame. There is also a priming charge which is usually around per prime (you should only need one). There is usually a small, per yard charge as well. This is in the - per yard. All-In, budget 0-0 for the pump.
Here is an important tip. You may be tempted to hire a "line pump" for this job as the per hour cost of the pump is a little less. However, line pumps usually require a special "pump mix" from the concrete supplier. It will have smaller aggregate and more cement. At any rate, it is quite a bit more expensive. A boom pump can pour standard 3,000 psi mix with regular agregate, which will save a great deal on the concrete cost.
Wash out is a necessary evil. If you hire the pump, they are going to have to clean up their equipment. The mess that remains is a small pile of concrete no more than 3-4 feet in diameter. There will probably be a hole on site somewhere down the road where it can find a home. If you are on the job and want to avoid the mess, have a hose handy and soak the pile after the cleanup. That will then the mix so much that the wash out can easily be broken into small pieces by a Bobcat.
The concrete trucks will also wash out their chute, but the mess isn't a big deal.
Ordering the mix can go either way. Typically, since you are paying the bills, you will decide the company that will supply the concrete. Once that has been determined, either you or the contractor that is pouring the footing can handle the dispatching of the mix. Typically, you want everyone to know the schedule. You will set up concrete on either "will-call" or "on the job". If you set th concrete up on a will call basis, you or the contractor will have to call the dispatcher to confirm the pour and get the concrete batched and heading your way. If you set it up as "on the job" then the mix should arrive at that specified time without any additional contact with the concrete supplier.
Concrete in footings is not typically vibrated. Concrete in foundation walls is vibrated.
I'm pretty sure every reply on this newsgroup will say to not adjust the mix. However, if you want to pour the footing, it has to go through the pump. If the mix is too thick to pump, you'll either have to adjust the mix or send the truck back. I'm pretty sure some water will be added to the mix on site. If you don't want to jeapordize the strength of your footing, then bear the expense for pump mix or a higher strength mix that will still have at least 3,000 psi at a higher slump. FYI, the code requirement for concrete for footings is 2,500 psi. So, if you adjust the mix with a little water, you may still be ok.
The only thing to watch out for in part contradicts my advice on #5. I said you may let them adjust the mix if needed. I did not say let them make soup out of the concrete. The main thing to watch out for is the footing contractor adding so much water that the concrete becomes free flowing.
Do you have any longitudinal reinforcement (rebar) in the footing?
You mention that vertical rebar spacing is 16". What type of foundation are you installing? Who came up with the 16" spacing? Depeding on the wall type and backfill heights, you may need rebar every 12" or you may be able to go as much as 24" or something different.
You realize the concrete pumper does nothing more than pump the concrete. Someone has to be there to hold the hose to place the concrete. That someone must also level the concrete and install the vertical rebar.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.