Post and Pier Foundation Depth

[Don_P]

Why do buildings that are obviously not built to modern code stand?
We're generally building for events that have a mean recurrence interval of 50 years. Start working the odds out and plenty of buildings never see a design event.
Then we use allowable strengths for materials and connections. Any individual part is hopefully several times stronger than it has to be to compensate for poor pieces or techniques and aging.

The inference when someone gives an example is that these techniques and methods have a proven track record. They most certainly do, which is why we have laws regarding their use. The average person botches the details pretty much every time. When put to the test these are methods of construction that have caused problems.  There is nothing wrong with it if it is designed by an engineer. A pro will not design what we see here, part of the legitimate cost is in doing it right. If you read that section of code through the last several code cycles it has been tightened, that is the result of the track record. With the engineer this morning I was even trying to put a pipe through a spot pier and footing and run a 4,000 lb tensile helical screw through it to help. "you're rotation still sucks and it's going to cost more". Conventional in many ways is conventional for a reason, it is very often the most cost effective way to arrive at the performance level required. 

[C.Oden]

Don P - The last one built was inspected and in compliance with code here. I believe this was addressed to me anyway.

We have many current builds under way up there by others going on as I type and all are inspected as it's right by Voyageur National Park and BWCA----  they are tight on codes and inspections.
If something else is required they'll make sure it is done. County-State-Federal  all get their hands in this stuff here.
I also cannot fathom short-cutting code as required though as its there for a reason

[MountainDon]

We have many current builds under way up there by others going on as I type and all are inspected as it's right by Voyageur National Park and BWCA---- 

Questions that come to my mind on this include? What types of structures? Are the structures, or parts of them engineered or are they built to the details set according to the IRC code book? You can't tell tell from the outside looking in if an engineer has had his hands on the design.

Is BWCA the Boundary Waters Canoe Association?  Just what sort of rules are encountered in their area of responsibility? Ditto NPS. Their rules may be more concerned with aesthetics or preventing deterioration of the waterways and riparian areas. I don't know, but wonder. Then there's the whole gamut of rules that fall under zoning regulations. Nothing to do with the IRC or structural.

Just asking as I don't like presumptions.

[SouthernTier]

Don P - The last one built was inspected and in compliance with code here. I believe this was addressed to me anyway.

We have many current builds under way up there by others going on as I type and all are inspected as it's right by Voyageur National Park and BWCA----  they are tight on codes and inspections.

C.Oden: you are probably correct.  However, the key thing is that "building in compliance with code" means that if you do anything outside what is prescriptively shown in the code book, it has to be engineered.  Engineered plans and their resultant structures need to be inspected, too.  There are probably some really nice well-engineered pier-foundation structures up there.  Pier foundations can pass strict inspections, but the inspector will be looking for the stamped drawings and the calculations.

[VannL]

C.Oden,
My main problem is the loamy soil I have here in central Alabama. Normally, all around me is clay, but for some reason my land is very loamy. This type of foundation is suited better for my soil type, and it will give me my root cellar back, which is awesome.

The AERC (Alabama Energy and Residential Code) follows the IRC, which doesn't list the post and pier system, which is different than stacking on solid ground which I believe you are talking about. My current house, built in 1954, has a stacked foundation and no level floors inside due to settling.

[C.Oden]

Sheesh all;

I don't know what to tell you. I read the above comments and then had to call an up north neighbor there who is just awaiting the septic at this time which will be spring he stated. To cold and harsh right now to do things.

He provided plans from the log home association he is a member of - that included the post and pier they included with the plans. Nothing had an engineer stamp or sign off and all was accepted as presented. The septic and well were different and required different permits and the companies doing this have or are providing and handling it. The plumbing he did himself, and the electrical he did also - except they had to have a licensed electrician do the hook up to the panel.

I am at a loss as to why things are different in different places. All I know is this is the manner they have been building these homes up there forever. It may be different inside a city there (?) but if it's outside in the county/country they don't.

If I hear anything contrare over the summer I will let you know

[UK4X4]

Its not only county but also specific areas which have diferent requirements due to historical issues

I had to have an engineer sign off on the foundation and structure before county would issue it

along with a letter from the engineer saying he had read the geotechnical report which was also required.

Down in the valley neither geotech or engineer sign off is required.

My engineer laughed at the mention of pier and beam....

just not suitable for the location or soils.

[Don_P]

You're going to find places where anything is allowed. That doesn't make it a good idea to take something a layman dreamed up and emulate or modify it. For the overwhelming majority of us this is, and has been, engineer required construction for a very long time.

I've gone back into the 60's in my codebooks which is as old as I have. It was non code back then in most of the US. piers have required engineering here on the books for at least 45 years. If you read the IBC on piers it describes something that is a good bit different than what I see people doing here, and has read that way for a very long time. I've cussed and discussed this issue with engineers at some length. After those discussions I'm comfortable quoting the law, I happen to agree with it. Again, it simply says, if you wish to build something not prescribed in the codebook, get an engineer to design it. In the latest version of the code it goes a step further. It says generically what I just quoted. Then in the foundation chapter it specifically states that if you wish to build pier and beam... it specifically singles it out... it needs to be engineered. Now what in the world are you thinking here, that is a very strong warning. Even if you can get away with it it might not be the smartest thing to do. But if you're allowed to it is certainly your right to chase the Beagle. No that was not specifically adressed to anyone just generally out to the ether.

[Squirl]

Again, sorry VannL.  I don't really mean this specifically directed at you.  When I see people in no frost depth climates, that can have one of the best foundations, for the same price, without having to make deep holes in the earth my reactions range from simple head scratching to yelling at my computer screen from jealousy. 

I was considering going with a pier foundation on my build.  When I worked out the math, even with my high frost depth (4 ft) it didn't make financial sense in the long run. It was about $1500 extra dollars and a bit of extra work.  To ensure the long run security of the massive amounts of time and money I was investing in the project, it seemed much smaller in comparison.  In addition to that, it would help my structure appraise for more and easier to borrow against or sell, if I were ever stricken with an illness or had need to sell it.

After all that, when I see someone with no significant frost depth, where the two methods cost the same and take almost the same effort and skills and they opt for the weaker option, it is a bit of a head scratcher. 

[VannL]

Squirl,
No problem. I asked the question because I didn't know the right answer. I got the right answer, which gives me a better base and I get my root cellar back.

My thanks to you, Don_P, MountainDon, SouthernTier, cholland and UK4X4. I am extra stoked to get on this project now.  Its like John says, no one is as smart as all of us.