Question on Foundation Techniques

9 years ago

I've done a fair amount of construction in the past. Aside from
doing interiors, I've built a cabin, added room additions, built decks,
mini-barns, finished out a houses inside, remodeled 3 homes. I'm no
stranger to codes, proper building practices, etc.

In my learning days, I was always taught that ANY structure that is
heavier than a deck should be put on a proper foundation using either
concrete footer or concrete piers, but it's OK to put a deck on posts as
long as they are set in concrete.

I have a neighbor who has, In My Opinion, a bad habit of building
sheds, room additions, even entire small houses on treated wood posts
set in gravel in the raw ground. He then builds up the sides using 2x6
treated lumber, and these often start at ground level - sometimes
actually touching the ground! Floor joists are then attached to these.
Mind you, these aren't decks, they are ROOMS or actual whole structures.

And, oddly enough, now his son has picked up the habit and is adding onto his home using the same technique.

Every fiber in my being screams "NO!!!" about this.

We live in a very wooded, termite-prone area and I've done tests with
treated lumber laying on the ground It lasts about 4 years on raw
ground and then termites/rot/insects start to invade into it. If he was
to use red cedar, I'd be happier, but they use standard treated pine 6x6
posts. And also, weight is an issue, not only of the structure itself
but also the contents and humans inside (this is a family of very large
people).

When questioned, he tells me that this should be fine, no problem on insects or rot "because it's treated".

I say that it's terrible and that at the very least the posts should
be set on or inside thick concrete piers (that extend 8" above grade).
Best practice says footer then pier or foundation, then wood. I think
the entire thing is going to rot out from under them within 10 years or
so and start sinking. Plus, insect intrusion into the structure, cold,
damp, etc...

And for anyone reading that is ready to start in about codes and
permits, there are none. The only codes and permits that are necessary
in the county for new construction are septic codes and permits.
Everything else is "whatever you want to do", no permit needed.

Just checking my sanity here. Aside from the lax county rules, is
this guy using a horribly bad practice or am I just being too cautious?

Featured Answer

worthy

9 years ago

last modified: 9 years ago

Wood foundations can have an estimated life of 40-100 years. One preservative manufacturer warranties for 75 years. One wood enthusiast claims wood foundations last forever. (At the end of forever, you're on your own.)

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Comments (10)

PRO
Mark Bischak, Architect
9 years ago
There is treated lumber than can have contact with soils and there is treated lumber that should not have contact with soils. If he is using the former, it should work fine for at least a year. Soil conditions, planting depth of posts, weather, and luck all are factors in how well the construction detail will perform.
PRO
User
Original Author
9 years ago
Thanks for your input, but a year? That seems awfully an short time for a structure...
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wishiwereintheup
9 years ago
My guess is these are the sort that handle rotting and sinking by stacking cement blocks underneath.
PRO
User
Original Author
9 years ago
Worthy, I understand that "properly built" wood foundations can last a long time, but six perimeter 6x6 standard treated posts put into the ground with zero surface treatment, not set in concrete and used to support the entire 10 x 8 structure ? No ventilation on the sides and this will support all floor joists. Yikes! Talk to me in about 6 years, I may have an update about a sinking room by then.
PRO
User
9 years ago
Take a look at the wooden pier and beam construction allowed along the Gulf. They swear that it will last 50 years before needing to be replaced. I just couldn't buy one of those houses on wood stilts. I just couldn't. I'd want them replaced with concrete piers. But, it's allowed. :rolling eyes emoticon:

Your neighbor will have a meeting with Karma before too long. Too bad it's poisoned the next generation though. Just hope the son learns from the big crash.
PRO
Virgil Carter Fine Art
9 years ago
Very common type of foundation for houses and outbuildings--in the 1700s and 1800s. Times and learning have changed. Pretty sure...
PRO
Anglophilia
9 years ago
I assume this person doesn't bother with a building permit and inspections?
robin0919
9 years ago
Your city/county NEEDS CODES!!!!!!! Made by engineers!
PRO
User
Original Author
9 years ago
As stated above, there are no codes except those for septic. I did an entire house build (and garage) with no permits or inspections needed. The only thing necessary was one septic system inspection by the health department. I was amazed myself about it but that's just the way things are. One county over? You need permits, inspections at every stage of the build, etc. and the codes are very strict. It's great in a way because I could get away with some wonderful design elements that won't fly in most counties, but then you also get people building the most crazy stuff you've ever seen. It's a mixed bag. The interesting part is how you have to, of your own volition, go to the county assessor and report your new structure and tell them to start taxing you. A whole new world.