pole building

[kalakoa]

Wondering if anyone has seen (or built) a pole building, or knows why it's not done here. Termites?

I've seen many a slab, post-on-pier, and combinations of these, but no post-set-in-hole other than fences...

[terracore]

This is a good question, as I have thought about building an AG building in this manner. The biggest stumbling block for me personally is I would have to hire somebody to make the holes, and that is sort of the end of a DIY project.

[kalakoa]

The holes aren't that expensive, but the DIY aspect might be exactly it -- pier blocks (even when poured in place with custom forms) don't require any special tools or skill, and are probably cheaper than pole construction.

[MarkP]

Is there some reason that the poles can't be reinforced concrete? I recall Rob Tucker describing a fabric tube product that comes off a roll that makes a form for pouring concrete any length you want. In effect the concrete piers would extend up 20' to form the poles in their entirety.

[Rob Tucker]

True. The fabric forming would be quite economical. The structural issue is to go deep enough to overcome any seismic or wind forces which might overturn the concrete columns. Concrete columns have more positive attributes than large wood posts.

But the design itself becomes critical. Lateral supports? Loads?

No way would I spend money on large wooden posts embedded in the earth.

[Seeb]

You can make pour posts laying down in reusable forms. But mix, reinforcing and workmanship is critical

[MarkP]

I don't know how the county would view this but I have stopped digging a hole (if it could ever have been called digging in the first place) because I hit a solid sheet of pahoehoe that bent the tip of my o'o. Due to my tunnel vision at the time I lamented that I would not be able to properly cement in a post. What about drilling 3/4" holes and epoxying 1/2" rebar into them, thereby tieing into a massive natural foundation? Just stop digging when you hit stuff too big to move, drill and set anchors or rebar, and pour concrete columns from there? Make wider at the bottom if deemed necessary to regain the leverage you lose from not going as deep, but really if the rebar is in there solidly it is as though the column extends down into the pahoehoe.

[Tink]

You would have to drill pretty deep for a 15 to 20 foot "pole" anchorage to work, as your anchorage would be transferred to tensile strength on the rebar, and "frictional" strength of the depth, keeping in mind the fracture strength of the surrounding pahoehoe without lateral bracing of the poles. The "general rule" of pier depth is one third of length of pole is buried ( 20 ft pole above ground, 6 to 7 feet of burial) on "freestanding" no lateral bracing. Poured footings are a different breed, as lateral bracing is required if the "pole" does not have an integral "mounting flange" for bolts to fasten "pole" to footing. Footing would have to be "engineered" for proper sizing to type of soil/wind load, etc.. Look at metal street light poles, cellphone towers, and the like to get an idea.

Community begins with Aloha

[bluesboy]

A couple of my friends have pole houses. They're around, but from what I understand, expensive.

[Rob Tucker]

Tink is likely correct. That is what has been required for steel post green houses.