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paulz
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# Posted: 19 Jan 2012 12:42pm
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Howdy,
If I want to pour a dozen piers for my cabin, would one of those Home Depot electric concrete mixers that hold a couple hundred pounds be enough for the job? A concrete truck won't reach my site.
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MtnDon
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# Posted: 19 Jan 2012 12:55pm
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I haven't used a HD mixer but I have a Chinese made mixer I got elsewhere. They work, but I find they hold/mix less than the advertised capacity. As long as I keep the volume to about 2/3 the rated capacity it mixes well. Just takes longer.
Is the plan to pour concrete in sonotubes up to the height of the beams/girders?
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paulz
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# Posted: 19 Jan 2012 01:05pm
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Thanks. Yes, that's the plan. I don't have frost issues, planning about 3-4 feet in the ground. Sounds like it might be an all day project just getting the stuff mixed and poured. Do you just shovel it in, mix, pour, repeat?
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Bevis
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# Posted: 19 Jan 2012 01:19pm
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Be just as fast mixing 2 bags at a time in a wheelbarrow and using a bucket to pour the concrete in the tubes.
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MtnDon
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# Posted: 19 Jan 2012 01:21pm
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Have enough 2x3, 2x4 on hand so you can firmly brace the tubes before starting on the concrete. If the pier moves, tilts, whatever after you start filling them it is nigh on impossible to set them straight when they have concrete in them.
Once all the sonotubes are set with bracing then start mixing. Be careful to not use too much water. That's an easy error to make. Use vertical rebar and keep it at least an inch inside the tube walls.
Are you pouring a footer in the bottom first or later? The footer should have a "X" of rebar at about half the thickness. An # shape rebar adds some strength to the footer. If you can bend the lower end of the rebar into a short L. That can be tied to the X or # and makes a nice strong pier.
The larger diamter the pier is the better it resists lateral movement.
How much height above ground level? If they extend much more than 12 - 13 inches or so above grade think about how you are going to add bracing. Holes can be drilled through the sonotube and J bolts set into the wet concrete. If you get them placed accurately that is stronger than drilling holes and anchoring bolts later. Cheaper too.
Will your beams/girders sit directly on the top of each concrete pier?
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paulz
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# Posted: 19 Jan 2012 01:57pm
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I'm still moving dirt around at my site. It's about 15% grade at the moment. Boy those sonotubes aren't cheap are they? A friend thinks I can just pour right into the holes I bore in the ground, then use 5 gallon buckets as pier forms, which would be good for about 18 inches above ground. Ever heard of doing that? I would them possibly have to use wood to get to the girders.
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MtnDon
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# Posted: 19 Jan 2012 02:34pm
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There is a 60 year old cabin nearby our mountain property. It has the type of foundation you mention. I have no idea how deep the concrete goes though. Probably not too deep as that building has moved slightly. If you do not have freezing temperatures to deal with that could work. In a locale where the ground freezes simply placing concrete in a hole in the ground is not a good idea. That's because the rough concrete gives lots of places for earth and water to freeze and then lift.
Another method would be to obtain foundation grade 6x6's. Foundation grade may have to be special ordered. It has a heavier amount of the wood preservative. Going with them you'd dig the pier holes 48" deep at least. You want the depth fpr lateral resistance.) and pour a concrete footer 8 inches thick with rebar and 16x16 square. Then set the PT pier and ram all the dirt back into the hole making certain to get the pier plumb vertical. That way the pier is one piece from bottom to top and the girder can sit right on it.
The thing I don't like about having a concrete pier, then a wood section and then the girder is the added connection point that provides. It's an extra point where failure can occur. Not everyone will encounter a problem but I have seen it. Just an FYI.
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TomChum
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# Posted: 19 Jan 2012 03:00pm - Edited by: TomChum
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Quoting: Bevis Be just as fast mixing 2 bags at a time in a wheelbarrow and using a bucket to pour the concrete in the tubes.
With an electric mixer you'll have to manage the generator the whole time, listen to it, lift bags up high, feed them into the mixer mouth, manage your cords move the mixer around. Go to the rental, return it..... I don't think a little mixer could possibly pay off.
I agree with Bevis. ( 2 or 3bag you'll figure out which you like) The secret to this method is to measure all the water for (3) bags into a 5-Gallon bucket. Mark that level on the bucket.
FIRST, pour all the measured water in the wheelbarrow. Water first. Then pour 2+ bags of mix, always pour mix ontop of water. Scraping up dry mix on the bottom of the wheelbarrow will waste your time. The intent is to have a super easy mix, like soup.
Then pour the last 1/2 bag in and mix to finish. You need a short-handled shovel to mix with.
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Anonymous
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# Posted: 19 Jan 2012 05:59pm
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I have mixed & poured a LOT of RED-I-MIX concrete for my home use pouring shed slabs, walkways & planting fence posts & foundation piers.
I use a contractor's size wheel barrow. Place 1 inch of water in the wheel barrow then dump in 1& 1/2 bags of red-i-mix concrete.
Stand between the wheel barrow handles, facing the wheel barrow.
Use a large garden hoe to mix as you add water. Move the hoe in a motion alternately away from & then towards you, scraping the bottom on the "toward you" stroke.
Add the remaining 1/2 bag of red-i-mix & more water to achieve the desired consistancy. Do NOT get it too thin.
In many cases you can dump the wheel barrow load directly into the desired place.
Hope this helps,
Cotton Picker
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cabinbiscuits
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# Posted: 19 Jan 2012 06:21pm
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Quoting: paulz Boy those sonotubes aren't cheap are they?
Paulz- You weren't planning on running the Sonotubes all the way to the bottom of your holes were you? As long as the ground is self supporting (meaning it doesn't cave in on itself after you bore the holes) you can just use the Sonotube for the above grade portion of your piers. Just thought I would mention that to you.
I've also seen sections of corrugated pipe (both metal and plastic) used to do the same thing. Not sure if that would be cheaper than Sonotube though.
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paulz
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# Posted: 19 Jan 2012 07:31pm
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Yes I was considering putting the Snotubes into the ground but it sounds like I might not need to. The ground here does not freeze and the holes should be stable.
I like the idea of putting timbers into the ground instead of on top of piers to reach the girders. I wonder if redwood would work.
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MtnDon
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# Posted: 19 Jan 2012 08:19pm
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Quoting: paulz I wonder if redwood would work.
Redwood would only work if it was totally free of any sapwood. ost construction common grade has sapwood.It must be all the darker heartwood. Cedar is similar and so is southern cypress, but again, no sapwood. All heart is likely to cost more than PT foundation grade. I believe locust is also resistant (and very heavy).
Check around your area for foundation grade PT 6x6 or even 8x8. Compatred to all the concrete and the labor mixing you may be pleasantly surprised. Here in NM I've bought foundation grade for less than 10% more than the usual stuff the big boxes stock.
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paulz
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# Posted: 20 Jan 2012 11:01am
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I have a large grove of redwoods, a pile of logs on the ground and a mill saw. I can make clear heart 8x8s but I don't know about the best method of putting them in the ground. Gravel underneath to let the water drain? Encase in concrete with a footer? Or just bury them in the dirt?
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MtnDon
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# Posted: 20 Jan 2012 05:17pm
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All heart redwood 8x8 would be good. It is insect and rot resistant.
A footer with an X or # of rebar in the middle of the 8 inch thick poured concrete would be an excellent footer, preferred over gravel as the concrete spreads out the load. Then pound the earth back in around the sides. Mound the dirt around the pier to make water run away from the pier. No concrete around the pier is needed if the earth is rammed in very well.That's how our cabin piers are set. Coating the piers with tar for about 6 inches above grade and 10 inches below grade can help discourage insects or organisms.
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cesjohn
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# Posted: 19 Feb 2012 06:24pm
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Quoting: MtnDon Coating the piers with tar for about 6 inches above grade and 10 inches below grade can help discourage insects or organisms.
Are you referring to "roofing tar"?
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mikehu1966
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# Posted: 8 Mar 2012 01:08pm
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Newbie Question: on the Concrete Footers, How long after pouring the footer, do you need to wait to put the post and back fill in into the hole?
Thanks Michael
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Just
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# Posted: 8 Mar 2012 01:41pm
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no need to wait long, just till it sets up maybe an hour ..
mikehu1966
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mikehu1966
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# Posted: 8 Mar 2012 01:50pm
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Thank You for the quick reply. Currently doing lots of planning for what I want to do over the next couple of years.
Michael
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MtnDon
Member
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# Posted: 8 Mar 2012 02:09pm - Edited by: MtnDon
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Next day is okay. The concrete will be hard enough to support whatever you are going then. Pack the earth back in hard. A digging bar with a mushroom head is ideal for packing. 'digging bar'
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exsailor
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# Posted: 8 Mar 2012 02:16pm
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This is just an idea, probably a bad one. I have been known to have many of them. Instead of a sonotube, why not use galvanized stove pipe six inch is readily available amd eight inch would even be better. It would protect the concrete from ground water freeze, or at least I think it would. It seems like a good way to cut foundation expenses.
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MtnDon
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# Posted: 8 Mar 2012 02:39pm - Edited by: MtnDon
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What kind of freezing do you have in mind? Lift freeze or the concrete itself freezing? It might help with lift freeze but no better than a sonotube. A round smooth concrete face is a round smooth concrete face. Even if the paper tube is removed or deteriorates over time frozen water/dirt should not stick to the smooth face enough to cause any lifting. That assumes the footer in below frost depth. One of the worst things is a rough hole filled with concrete. All sorts of places, angles, etc for frozen earth to act with uplift force. Same thing for filling holes around wood piers with concrete. The dirt that came out of the hole is better. Well tamped of course.
One thing that many don't give proper thought to with concrete piers is the connection from the concrete to the rest of the structure. It is an especially bad idea to place a short post on top of the concrete and depend on metal brackets to connect everything. Each joint is a hinge waiting for some external force.
Many times a foundation grade PT 6x6 or larger pier set on a concrete footer, below frost depth, makes a more sturdy structure.
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exsailor
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# Posted: 8 Mar 2012 02:54pm
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Don,
I was thinking more of a form using stove pipe, much like sonotube. It would prevent freeze lift by keeping the concrete smooth. You could set a J bolt in the wet concrete and then bolt your foundation beam to the pier you poured. The same J bolt would work to address the potential weak points you mentioned as well.
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MtnDon
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# Posted: 8 Mar 2012 03:32pm
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Concrete piers poured to the exact height with the beam secured to an anchor can work well. It still leaves the problem of how to properly secure good bracing to the concrete. If everything is well thought out and prepped, concrete piers can be great. Seen too many poorly thought out piers of all types though.
Not sure there is a price savings though or any real advantage over the cardboard tubes. ???
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soundandfurycabin
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# Posted: 8 Mar 2012 03:53pm
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Using stovepipe or ducts does have an advantage in that it won't turn soggy if it rains between setting the forms and pouring concrete. Lets you sleep better especially if you have to get your formwork inspected before filling it, and you don't know when the inspector will get out to your place.
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AYP1909
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# Posted: 8 Mar 2012 04:22pm
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Quoting: paulz Boy those sonotubes aren't cheap are they
I have found concrete form tubes to be relatively inexpensive; ex. 8" by 4' less than $6. You didn't indicate what area you will be building but since freeze doesn't seem to be an issue, I will recommend using tube forms as opposed to pipe.
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mikehu1966
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# Posted: 14 Mar 2012 02:20pm
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Would placing 4"x8"x16" concete block in the hole to make a 16"x16"x8" thick base work too?
Or is the cement foundation better because it will cover the bottom of the hole better?
After reading lots of posts, I am taking many notes on build the foundation as correctly feasible for my $
Thanks
Michael
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