Another foundation question...

[John_M]

I am confused about the pros and cons of a post and pier foundation versus a crawl space foundation.

I am building my cabin on slightly sloping land.  I was going to put it on post and piers.  The size of the cabin is 18x32.

I contacted my local building inspector in the town I am building in and he told me that although post and piers are not the best foundation for longevity he has to allow them by law.

Is a small crawlspace possible on sloping land (by possible I mean economically feasible)?

What are the benefits (cost and practicality) of either of them?

Are posts stronger if they are in the ground or connected to the concrete footers with some type of connector?

[Micky]

I choose to go with a continuous foundation.  The biggest con of doing the continuous foundation was that I couldn't do the work myself.  The reason I chose the crawl space foundation is that I was told by the bank that resale is difficult with a post and pier foundation because it is harder for the next owner to secure a loan.  I don't know how true this is, it is just what I was told.

Another advantage for me is that it is easier to keep the pipes from freezing in the crawlspace.  I think you can also do this with post and pier if you close in the sides.

I have a 38" crawlspace and I am planning on using it for some limited storage.

[John Raabe]

It wouldn't surprise me if the post and pier foundation might have some insurance companies raising rates. The older P&P systems got a bad rap and just like wood stoves can have problems if not done right. (My insurance is higher because I heat with wood.)

Modern materials and building techniques http://countryplans.com/foundation/index.html can solve most of these issues and skirting can make it about as well sealed as a concrete crawler. Such a foundation will last longer than the structure and this type of foundation is not unusual in many parts of the country.

But where it is not common, and when the money is available, I would do a perimeter concrete foundation for a larger home, especially one I expected to sell later.

[John_M]

Thanks for the info.

I will probably go with Post and Pier!

What about the difference between posts in the concrete versus posts attached to the concrete?

Is their an advantage to one versus another?

[Amanda_931]

At a dinner last week, the most experienced builder among us (decidedly NOT me) stated that well tamped in crushed gravel around a post was better than setting in concrete because if it failed (same probability, he thought--whether from rot, or in that case, flash flooding) it would be a whole lot easier to replace.

Replaceability would be better with an attached post.  Unless the connector was the weak point there.  Or unless the powers that be required concrete.

[John Raabe]

Posts are under the most critter attack within 6" either way of the soil line. This is why tarring a PT post around this area and then packing it with soil or gravel that drains will give you the longest life.

However, spiking the bottom of the post and burying it in concrete will give it the most strength, weight and uplift resistance from a bracing point of view.

Maybe the best would be to pour concrete up to 6 or 8" of the soil line and then pack the rest of the way with gravel?

[Okie_Bob]

John, if critters are the problem, why not go with steel pipe instead? You can get used pipe, at least around here very cheap. I plan on using 6" thick wall (at least 1/2"). I will bury them in concrete about 3' deep with the concrete extending about 3 1/2" above grade. On my sloping lot, the pipe will be about one foot above grade and about 6' on the steep end.
Even considering rust, this should last many more years than even my grandkids will be around to worry about it.
Jonsey has an excellent drawing for using pipe, he calls them 'stumps' and a method of attachment that really looks good and I plan to copy.
Comments?

[John Raabe]

I agree, steel would be a good long lasting choice.

It does involve another set of skills and tools that not everyone has, and things like skirting might be a bit harder to work out.

[JRR]

I once welded up a platform for a jet water pump.  I used heavy 3" angle.  The platform was thoroughly cleaned and painted with Rustoleum, then placed in a poured concrete footing ... inside the well house.   Because of condensation, rust soon took over and the platform lasted (maybe) 20 years.  Because of the constant wetness, the steel could never be recoated.
I'm sure I could have used better (elastomer?)protective coatings, or I could have bolted up stainless or galvanized steel and gotten lasting service.   But the unexpected failure of plain painted steel made an impression on me.

Unless money, wetness, or termites are not problems, one might consider custom-made reinforced concrete posts for "post and pier".   Should do the job quite well at a fair cost.

[Okie_Bob]

JRR, I don't think many foundation post and piers would ever be subjected to constant moisture as you describe.  My lot is sloped and drainage is good.
We are on Cedar Creek Lake, about 60 miles SE of Dallas, Tx. The lake opened in '65 and since there have been several hundred boat houses built in the water. Just about all of these are built with steel pipe pillars, sunk into the bottom of the lake.
Some of these have been up for at least 30 years and to my knowledge none have failed due to rust.
I have only been here 6 years and I don't know how long my boat house has been here prior to buying the place. But, five years ago, the lake went down enough that I was able to clean the posts with a wire brush and chipping hammer and apply Rustoleum primer. It is holding up quite well and I can find no problems with any of the posts. I don't know of a worse condition for steel pipe. If my house will last 30 plus years I don't think I'll have to worry too much about it!!! (that would make me 92 plus!!!!)