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Nirky
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# Posted: 28 Jan 2015 18:05 - Edited by: Nirky
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So you're probably already heard of or seen the Diamond Pier system of pier foundation.
It consists of concrete heads with angled holes through which galvanized pins of various lengths are pounded through to anchor securely to the ground.
The Diamond Pier system costs are far too high though, but it sounds like a perfect system for a cabin. So I got to thinking...
For my version of the Diamond Pier system I plan on digging a smallish 12" or so wide hole about a foot down, then from inside of that hole pounding in 4 (or more) 4-ft long sections of 5/8" rebar, mimicking or exceeding the angles of the Diamond system. Then I'll use a big coffee can or equivalent as an elevated form to contain all rebar ends. Finally, will pour in concrete and add a 2-ft long threaded rod while the concrete is wet for easy bottom plate attachment.
It will be fast, I don't have to dig a labor-intensive big hole down to frost line, don't have to haul around lots of heavy gravel or concrete to fill, and is very inexpensive.
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old243
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# Posted: 29 Jan 2015 11:13
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How would an expired, 20 pound propane tank work as a container for our concrete. cut holes in bottom for your re rod, cut a hole in top to get concrete in , There is usually a carrying handle at top that would give you a flat surface for joist. Fill tank with water before you start cutting. Or a piece of sono tube , might be simpler. old243
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Nirky
Member
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# Posted: 29 Jan 2015 11:28
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Piece of sonotube will work perfectly.
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knock
Member
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# Posted: 30 Jan 2015 22:57
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How long are you wanting this pier to last?
The 5/8 rebar in direct contact with the soil will rust out over time.
1/2 galvanized pipe could be an alternative.
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Nirky
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# Posted: 30 Jan 2015 23:11
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True, 5/8" rebar may only last 50-60 years in soil.
If you plan on your great great great grandchildren enjoying your cabin, galvanized pipe would be fine. 
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Don_P
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# Posted: 31 Jan 2015 09:17
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Part of what makes the pier work is the diamond bottom to split frozen soil rather than a flat bottom to be lifted by frost. I think you'd have to make a form of that shape. Foam makes decent cores that could be drilled out quickly for the pins, or pipe sleeves cast in. It looks like they use 1" galvy pipe minimum. Read the ESR report on alternative methods, in this case pay attention to the "uses" section. We just drove 32 pipes 2" dia for the high tunnel in rocky soil, the soils and rocks from the top of the mountain that has migrated down over time. We had a large Hilti percussion hammer, a sledge and driving dolly, a post hole driver, a digging bar and a pinch bar. The last two I had to slip into the hole and drive through or push aside deep underground rocks. It took my elbows weeks to recover, I guess if the soil is cobbly/rocky, this is not the easiest way to go. In clean soil It should work within its' capacities... they are not high. The little 10x12 on 4 posts we were talking about on Mart's thread, I was sketching and figuring a little bit, it's coming in at about 4,000lbs/post, the capacity of the regular diamond piers is about 2700 lbs.
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morock
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# Posted: 31 Jan 2015 10:55
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From my very limited experience in the world of piers, you need to evaluate your soil first. Not all pier systems work in all conditions, even if the company brochures say they do.
Climate and frost depth should all be considered. Sometimes just some rigid foam under pier block are enough.
Next, I would figure if i really need such support for the size of the cabin. Lots of past postings on how to build on skids with stiff walls to take a little rock an roll.
I went with a promising technology in tough conditions and was assured it would work. So far I'm not very happy.
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silverwaterlady
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# Posted: 31 Jan 2015 16:21
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One thing I've learned about cabin foundations... Don't skimp and don't experiment. Trust me on that!
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Nirky
Member
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# Posted: 31 Jan 2015 17:41
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Morock, did you go then with a diamond pier system?
This is what they say about sound soils:
For most residential applications there are two prescriptive penetrable soil types: 2000 psf sands and
1500 psf silts or clays. Soils that do not meet the prescriptive bearing strength in the local code will NOT
provide expected foundation capacity. Ask your local code official for soil information regarding your site.
(Information regarding soil type is available at the U.S. Geological Soil Survey Site managed by the
Department of Agriculture: http://soils.usda.gov/.)
Diamond Pier foundations require sound soils, which include bearing strengths of at least 1500 psf in
silts and clays or 2000 psf in sands, and clean foundation areas without unconsolidated backfill, soil
contamination, buried debris or utilities, or improper drainage. Sound soils also include areas where
traditional concrete piers, accepted by local codes, are able to provide adequate bearing to support the
total load of the project or to protect the structure from the negative effects of frost heave.
Many soils are not considered to be sound. Some examples of unsound soils include soils that are
weaker than 1500 psf, highly expansive or heave-susceptible soils that move vertically more than an
inch, and soils with unknown characteristics. Soils can also be weakened when they retain standing
water, and in certain types of soil this can cause severe heave problems. Weakened soils due to
freeze/thaw cycling or excessive water can reduce the bearing capacity or uplift resistance of the
Diamond Pier foundation. A site depression with standing water or the potential for water to pond, pool,
or saturate the soil may be an indication that the soil is not sound. Downspouts that discharge at or near
a foundation may also cause complications at a site and indicate unsound soils. Soils near home
foundations may not be sound if they have been improperly or loosely backfilled, which may also
facilitate the pooling of water. Drainage ditches, creeks, or nearby ponds may also indicate that nearby
soils are not sound. Diamond Pier foundations should be set well away from these features. Where
unsound soils exist, a special construction conditions review must be performed.
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creeky
Member
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# Posted: 31 Jan 2015 17:50 - Edited by: creeky
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small cabin. fun experimenting. no regrets.
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JJHess
Member
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# Posted: 1 Feb 2015 09:40
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I do a lot of foundation work, as well as remodeling & new construction. I've looked into these, more just to get educated than to actually use them. IMO, there are more soils this system will not perform well in than there are soils ideal for this system.
Full disclosure, I am also a Techno Metal Post dealer/installer so I am well versed in soil types and foundation systems. If I were building my own cabin that I wanted to last for a few generations, I would not use this system. There is no way to verify you will have the necessary bearing so how will you know if the soil you are sitting on is stable?
On the other hand, if I were building a small 'disposable' type cabin that I only wanted to last for my use, then I'd experiment with other, less costly, methods. A home made diamond pier may be fun to try. But as was said earlier, the reason these 'work' is because of the shape. Don't use a bucket, tank or any other form with a flat bottom.
Give it a try and let us know how you make out.
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morock
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# Posted: 1 Feb 2015 09:41
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Nirky, no I did not use Diamond Piers. From their disclaimer list, sounds like these are no better than standard piers or blocks. Best advise -- Soil conditions are critical. If you know how your soil will behave over your temperature range, choose your structure accordingly. I'm not sure where you are, but I'm in Canada. With no snow cover under the cabin the cold can penetrate deep into the ground. Last winter I saw frost/ground heave of 8-10 inches.
I'm probably in the worst soil (wet clay) possible too.
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silverwaterlady
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# Posted: 1 Feb 2015 12:15 - Edited by: silverwaterlady
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Morock,My foundation woes will be posted along with the big fix this summer. The job was not 100% complete last summer when we returned home so my photo album is not complete. All the above was the problem plus the snow melt alongside the cabin from the mountains of snow sliding off the roof.
We did not have diamond piers. Used blocks and at the time had no knowledge of foundations and left it up to the builder. Big mistake!
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rockies
Member
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# Posted: 21 Mar 2015 19:52
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Hi, why not use Techno Metal posts? They just screw into the ground.
http://www.technometalpost.com/en/home/
A small machine comes out to your site and can set all your posts in a couple of hours.
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Nirky
Member
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# Posted: 21 Mar 2015 21:33
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Quoting: rockies Hi, why not use Techno Metal posts?
I'm guessing, but probably the cost.
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morock
Member
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# Posted: 21 Mar 2015 22:22
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Actually, thats what I used .. Techno Post. I can't open my front door right now because the frost has grabbed the post, with a frost sleeve and lifted it.
Like i said earlier I am in wet clay and a long very cold winter. Yes it was expensive too.
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Nirky
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# Posted: 22 Mar 2015 01:52
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Quoting: morock the frost has grabbed the post, with a frost sleeve and lifted it.
They sunk the post well below the frost line and it still lifted?
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creeky
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# Posted: 22 Mar 2015 09:18
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morok. i feel your pain. the last two winters have been terrible. I put some sheet scraps of xps insulation on the ground around the posts on my bathroom as one was really going. and it stopped the rise. now i'm waiting for spring. I plan to insulate around the posts with xps this summer. keep the frost line up a bit.
and fingers crossed. this is the last bad winter we get. let someone else take the arctic vortex for a while.
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morock
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# Posted: 22 Mar 2015 11:26
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Creeky - I tried some XPS this year after the same thing happened last year, however now I think the steel post is acting like a conductor and transmitting the cold. This summer I will insulate the post and expand my XPS coverage and see what happens. BTW I'm using 4 inch XPS too.
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JAN
Member
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# Posted: 30 Apr 2018 16:36
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Quoting: Nirky add a 2-ft long threaded rod
Why a 2-ft length--if your footing is 12 inches deep? Retired Home Economics teacher here.
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KinAlberta
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# Posted: 30 Apr 2018 18:22 - Edited by: KinAlberta
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As a aside, this happened at a nearby lake at the start of the year. Freezing ground water... and maybe winds over the lake ice
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