[oo3]

1st thank you to replies to my 1st question - in this area ( new orleans suburb) - frost line not an issue but soil type and settling are - slab houses are built on pilings driven maybe 40-50 feet into ground before hitting a firm layer -
- so for deck 1 and 2 code dept okays a footing using 8" tube and didnt even ask how deep - ( went 24" and used simpson post base) - on further research this may well be inadequate - ( go ahead i am here to learn ) - one contractor i spoke with said settling here is just something you have to deal with - of course i dont like that answer and hope for a better solution -
- so what type of footing would you use for porch/deck 35' across front of house - 5' out and 3' to top of deck material - in this type of soil
a note on settling - my house 1600 sf on slab built in mid 70s had a 4.5 inch differential measured on interior floor - here that is considered normal - i say had because this spring it was raised 3 feet and leveled - thats right slab house raised 3 feet - quite an interesting process - oo3

 

[Greg Di]

If your soil is THAT bad, an 8" pier is useless.

You want the absolute largest pier base you can do within reason to give the widest base possible for the pier.

A Bigfoot comes to mind, but if you whole house is sinking in the dirt then even a Bigfoot will sink at some point. Kind of like putting a needle through a sponge.

Glad I'm not building in those conditions!

 

[Tom Struble]

how about these Greg?

http://www.pinfoundations.com/

 

[Winchester]

how about these Greg?

http://www.pinfoundations.com/

Have you ever used these?

If they actually worked, that would be pretty neat.

 

[Greg Di]

how about these Greg?

http://www.pinfoundations.com/

Yeah...I wish.

The best part of the installation instructions is when they tell you to "dig down to obstruction, remove it, then recompact the soil and try again".

So, in other words, if you hit a rock, they don't work.

I have never NOT hit a rock. Ever.

 

[Tom Struble]

I was thinking more for the OP bad soil

if i was a rock i wouldnt dare stand in your way :no:

 

[RobertCDF]

I would imagine they would work fine where frost heaving is not an issue.

 

[deckman22]

When I've done fishing piers at the coast we get a pile driver to put in the piers. Nothing more than a backhoe on a barge, using the hoe to drive the piers into the muck.

I would suggest something similar, say 8"-10" round CCA treated 1.0 (not ground contact .40) or creasoted piers. Get them long as you can & get someone to smash them in with a backhoe after you've dug your holes deep as you can. Once the pier is down far as you can get it drive some big spikes into it & pour concrete into the hole. Chainsaw the tops off as needed.

FWI, I've found the creasoted piers hold up better in saltwater than TP piers. Pick them out yourself, getting the ones from the center of the log.

 

[JamesKB2]

We use helical piers in bad soil (around the lakes) here.

http://www.helicalpierworld.com/

Simple, quick, strong. Some houses are going on ten years, no settling issues.