Helical Piers?

Started by GaryT, August 21, 2015, 11:05:51 AM

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GaryT

I'm just starting on the design of a 24X28 camp I want to build in New Brunswick, Canada.  Talking with the building inspector up there, I asked about using piers instead of a concrete crawlspace foundation, and he mentioned helical piers - I had not heard of them before (must have had my head in the sand for the last 20 or so years, working as a one-man residential renovation contractor).  I used the search engine hear and found 5 threads where they were mentioned, but not much actually about them.  So my question is: has anyone here had experience with them, and if so, how did it go?
Thanks,
Gary

MountainDon

My brother in law used helical piers as a remedy in a situation where he built a deck on non code piers and the building dept caught him.

UK4X4 used them because of the unstable soil conditions where he was building.

MY BIL's were installed some 8 years ago and from all I hear UK4X4's cabin is doing fine. Doing better than most of the neighboring builds near him; all on the same unstable soil.

To me they make a lot of sense for remedial and repair work as well as difficult soil conditions. It seems like most (all?) of them require a hydraulic machine for installation. Is that going to be any less expensive than a traditional concrete foundation with crawl space or a concrete slab?  I have no idea, that's why I ask.
Just because something has been done and has not failed, doesn't mean it is good design.


Don_P

From what I've seen on the web their engineering is lightweight and their assumptions about what is tolerable movement and placement are pretty broad. I recall a thread on another forum where the owner wasn't happy with how much the building moves.

GaryT

Thanks for the replies.  Hope some folks with actual experience with them chime in.  So many decisions...
Gary

kenhill

Here is a website for informational background:
http://tmpalaska.com/


GaryT

Thanks for that link!  The piers certainly are versatile, but man, they look so small to be supporting so much.  I did get a quote from an installer in Fredriction, NB:  20 piles for the 24X28 plus deck - $4550.
Gary

comanche

I have some on a 12x16 cabin. They were about $450 each and we had TMP alaska install 12. There is lateral movement in the cabin when you move side to side, but thats the only complaint. We still need to cross brace it. There has been no heaving in the 2 years they have been in.
Homer, AK

UK4X4

Actually I looked at them , but did not use them in the end, due to the possible movement sideways....could not guarantee that they would all move in the same way,

1 cabin on my hill used one for a beam support under the house, something moved, and caused the beam to twist and the floor dropped in the middle.

I ended up with a 4ft thick crushed rock drained pad , and then a monolithic foundation, built to stay in one piece even if things moved.

My area has known issues due to the sand silts and clays, and the spring snow  run off from the Mesa above, it's probably not a comparable scenario

I did like the technology though , and you can use them as a base for a concrete sonotube type foundation, as well, ie the pier ends at ground level in a pit which you then
Can fill with concrete to either construct a pad or sonotube pier

akwoodchuck

The techno posts have all but replaced sonotubes in this area in the last few years... I've worked with them on projects ranging from small attached porches to an entire two story, three bedroom house. For the decks, they're great, too shaky for anything freestanding IMO. Have had trouble in the past with their installation being significantly off layout....like 3"-4"! Hard to set a beam in that! For situations that call for pilings, I far prefer 8" well casing, with welded saddles.
"The lyf so short, the craft so long to lerne."


GaryT

Well, after lots of research concerning the viability of the site we want to build our camp on, helical piers have become the only way to go.  The site had been quarried some years ago, and filled with a variety of materials, including lots of organic matter from a nearby planning mill.  Had a licensed septic guy come in and dig test holes for septic...a definite no-go.  Fortunately, there is, immediately adjacent to the camp location, suitable septic ground.  Landowner ( an old friend) agreed to include that ground in the purchase.  So I had a well-recommended screw pile contractor come in and test the site...totally do-able from his standpoint.  Just that the piers will have to be 14' deep to get to untampered ground.  You do what you have to do.  They now have bracing to prevent lateral movements.  I also visited a site he had just done.  Huge camp all on his piers.  Owner was there and he was a happy camper (pun intended).  Entire pier project done in 6 hours.

Anyway, a few pics of the test:




Winter view from camp site of the Miramichi:


Gary

ChugiakTinkerer

There's a lot to be said for "sone in 6 hours" and you being able to set beams right away.  No 40 day cure for you.  Looks like a beautiful place, and glad you found a foundation solution.
My cabin build thread: Alaskan remote 16x28 1.5 story

GaryT

I was really happy to come up with the pier solution.  They're not making river front property anymore, at least not on the Miramichi and the site was the only available land in the area we want to build near good friends and fishing.  Fortunately, one of our nearest neighbors-to-be is a surveyor; he did the subdivision plot "on the house" and is taking care of the permits along those lines for us.  We're 570 miles away from the site and are only allowed to live there 6 months of the year as non-Canadians.
Gary