Why we built a post and pier foundation

A few folks have asked recently why we built our deluxe shed up in the air on piers.  You see houses on piers near the ocean often enough but West-by-God-Virginia is not terribly near the ocean (really, check a map….)  Near an ocean, it makes sense to raise your house in the air for when hurricanes blow through or when gators need to mate (more for my bayou friends than my ocean friends).

Isaac laying in a sonotube for the pier

Isaac laying in a sonotube for the pier

The first problem we had in building this house is that we had absolutely no facilities to make building a house in the least bit easy.  We had no water, no power and no flat land.  I studied A LOT before charging head-long into house building and among foundations, it seemed that the post and pier foundation required the least amount of concrete to be mixed and would be the most straightforward for a building neophyte to pull together.  All of the concrete for this place had to be hand mixed as there is no driveway or road for a mix truck to deliver concrete.

Really helpful advice on working with concrete

Really helpful advice on working with concrete

Mixing concrete by hand for the post and pier foundation

Mixing concrete by hand for the post and pier foundation

I figured that pouring one pier at a time would be slow enough to do (unlike dealing with an entire load of concrete on a truck) that I could take the time to make sure that stuff was plumb and level and fixable if I screwed up.  It turns out that it is a slow process but definitely not simple.  I learned how to tie rebar and how to mix concrete that was not too wet and not too dry and I learned how to keep a sonotube (cylindrical concrete  form) plumb even when pouring shovels full of concrete into them.

Pouring concrete in the tubes by hand

Pouring concrete in the tubes by hand

Concrete form tubes for our post and pier foundation

Concrete form tubes for our post and pier foundation

Our soil is red sticky clay with very little rock.  I read a lot about soil types and found that if there isn’t a sufficient base under a pier, the cylinder that is the pier will push down into the soft clay like a pin through butter when the weight of the house is added.  Most recommendations suggest that a larger footprint cylinder will prevent the sinking.  They make a flared base that expands the footprint of a typical 8 inch sonotube to prevent sinking but I didn’t have those handy.  The other option is to use a bigger tube.  Twelve inch piers seemed to be the consensus for size and they were readily for sale.  Let me tell you, for simple cardboard tubes, the folks that make the forms are pretty proud of their product.  Anyhow, in addition to the size of the base, the depth is important.  In addition to needing to dig the piers deeper than the frost line, deeper piers provide more contact between concrete and soil.  That friction also prevents sinking as well.

Setting the first of the posts for our post and pier foundation Making sure the posts are plumb for our post and pier foundation

Anyone still with me?  Yeah Mom, you don’t really count here.  Anyone else?  Ok, well just in case…we connected 6x6s to the pier with a metal post base which was bolted to a J-bolt embedded in the concrete.  In some ways, I would have preferred to pour taller concrete piers rather than add a wooden post but my back wouldn’t take it.  I also did not know if I could lift that much concrete over my head to pour it into the forms.  Anyhow, the only reason it matters is that the joint between the concrete and wood is a hinge point…a point of weakness.  Solid concrete to the base of the house would have eliminated that hinge point.

The bolt embedded in the concrete pier

The bolt embedded in the concrete pier

A 6x6 post base that attaches the post to the pier

A 6x6 post base that attaches the post to the pier

My goal is to minimize hinging by making good connections, by making things plumb/level/square and by using geometry.  I connected 2×6 boards from the top of one pier to the bottom of adjacent piers.  By making triangles with the boards, the weaker tops of the 6x6s are connected to the more stable lower portions preventing movement.

Cross-bracing the posts using geometry!

Cross-bracing the posts using geometry!

So, once all of that is done, I have a pretty stable base on which to build everything else.  I am not sure that I made a compelling case for building a post and pier foundation but I have no regrets  and it definitely raises eyebrows.  Initially, I had hoped to be able to ignore the space underneath but I will definitely have to do something to protect the area beneath our deluxe shed.  The wind really howls up there and I have no interest in a Dorothy/Kansas/Toto deal where my house gets carried away by the wind!

 

See all of the progress on the cabin


11 thoughts on “Why we built a post and pier foundation

  1. Cool! I read all the way through and understood most everything. One thing made me cringe, though…”My goal is to minimize hinging by making good connections, by making things plumb/level/square and by using geometry.”…..
    Dangit, all these years I’ve purposefully forgotten the torture of geometry class and you go and prove we need it after all. (((sigh)))

  2. Thanks honey, I understood it all. Yea, right??!!.. All I know is the house is still standing and fairly level…I think. anyway thanks for the explanation.

  3. Sorry, you lost me right after the sex education class on the mating habits of alligators. But I did enjoy the photos, especially where you had Issac do a Chinese Handcuff demonstration.

  4. Answers all my questions too. Initially I thought it for a cow shade so you can keep a fuel source, i.e. cow chips, close.

  5. I’m laughing out loud over your comments again Warren! :) So you didn’t have to dig down to put the piers in? That is what puzzles me about it all. We built our house on flat land with footers where they dug down and poured cement in there type of deal. I hate to admit it but the piers scare me. I think once you put the block under it it won’t scare me as much. I guess I have some strange fear that has no name! lol

  6. Angela – the piers are definitely dug into the group. Each has at least 3 feet below the surface which is pretty typical for footers

  7. We’ve used those concrete things a lot – for our tack shed, for our playset – they really are handy!

    Your Captcha is killing me. I always forget to do it and then my comment is erased! :-( I hope those rotten spammers leave you alone soon so that you can be captcha free again ;-)

  8. My parents cottage was built on a post and peir design. It lasted for 40 + years until the frost of the Candian winters finally got the better of them and caused most of them to start tipping. Last summer they had a full foundation put in. Quite a job having the old cottage lifted off the peir’s and a new foundation built and then the cottage was placed back on.
    One thing to watch for is porcupines they love to get under there and chew on the wood. Great job though and lots of fun to follow along on your adventures.

  9. varunner7 – sorry about the captcha…it’s a pain but the spammers still hit me…it’s just a lot less now

    Dave – thanks for leaving a message. I am hoping to beat the frost but there are lots of things to worry about there I think. I will be happy if I can be free of frost problems for 40 years though!

  10. Ed – the cows seem to have finally either decided to stay home or they are in someone’s freezer…not sure which. I think I will burn wood though instead of cow chips…that curing time is a lot to overcome!

  11. Thanks for taking the time to explain each step. I just finished pouring a similar foundation in Alaska this summer and was curious how other people had done their’s (I have a bad habit of studying up on something after I’ve completed it my way, go figure :)) One idea that a friend shared with me is to make a large foot with 2×8′s (I made my feet using 2′x2′ squares made out of scrape 2×8 material.) I used rebar bent in an L shape to connect the sono tube to the foot and had a grid of rebar wired for the foot that I wired the L shaped rebar to. The downside of having such a big foot is that you have to dig a really big hole. I’m hoping the extra area of the foot really spreads the weight of my cabin out and provides a really substantial flange to prevent frost heaving. Thanks again for all the info, this would have been very helpful at the start of my project had I seen it.

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