how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
(OP)
I friend is adding covered patio.
The patio column will be on drilled pier.
I can calculate the wind and all other forces that will be on top of drilled pier.
But how do I estimate the drilled pier skin friction, bearing and lateral capacity without geotech?
any other better option for foundation of column patio?
Is it cheaper to use DIY helical piles?
there is already have a 6" existing slab that we rather not on dowell into.
we'll put the drilled pier outside the existing slab.
The patio column will be on drilled pier.
I can calculate the wind and all other forces that will be on top of drilled pier.
But how do I estimate the drilled pier skin friction, bearing and lateral capacity without geotech?
any other better option for foundation of column patio?
Is it cheaper to use DIY helical piles?
there is already have a 6" existing slab that we rather not on dowell into.
we'll put the drilled pier outside the existing slab.






RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
Beyond that comment, I would recommend a geotech. You could look for ansi/asae shallow post foundation design for some guidelines. However, don't forget about frost jacking depending on the location.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
You can't. You need to know the type and characteristics of the subsoil.
BA
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
I do have an idea about soil because I know the location
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
Can I make the weight of drilled pier heavier than the tension. that should take care of this patio being blown away by hurricane
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
I see conflicting recommendations regarding this.
We can put 4 columns so the patio can be stable as detached and just use proper flashing for patio roof to house siding.
Based on google, more DIYer or contractor recommends connecting to ledger house regardless if I can make it stable as detached.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
http://www.awc.org/pdf/codes-standards/publication...
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
he wants the patio column and purlins made of steel instead of wood.
should this be connected this to ledger of house?
I get conflicting opinions which is better.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
For tension loading, absolutely, size the drilled shaft to be heavier than the uplift (and be able to transfer that load to the shaft, of course) and you're good to go.
For lateral and gravity load, you'll need to make reasonable observations and assumptions about the material. Hopefully you can lean on local experience or a basic soil mechanics class in university to figure out a basic soil classification. With those in hand, take a look at NAVFAC or VulcanHammer.net to find some general guidance.
For patio-sized drilled shafts, in reasonable material, I would suspect that end bearing will be more reliable than skin friction.
What kind of foundation does the rest of the structure use?
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
Use concrete weight.
For bearing, a practical footing size will likely give you a reasonable amount of capacity. Use a conservative bearing capacity. It's likely that your jurisdiction has some presumptive values you're allowed to use that are really conservative. Go with that.
For lateral capacity, use the post foundation equations in the IBC. There are presumptive values for allowable lateral capacities that can be used in that equation as well.
I agree that a geotech report is probably overkill for a reasonably low risk residential structure. The tradeoff for that, though, is that your assumptions need to be more conservative to account for the risk.
This guy should check with the local building department. I know that around here as soon as you start using steel for anything load bearing it's pretty much immediately assumed to require engineering. There are prescriptive designs available for wood, and it's reasonably reviewable by the building department, but there aren't generally for cold formed or rolled steel.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
For designing something like this, we never assume any skin friction on the pier, small residential is typically designed using only the bearing capacity at the base. Helical piles can be used as long as the gravity and lateral loads at top of the pile are provided to the installer.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
I did give the shallow post reference, which is giving him some conservative assumptions. That guide goes through everything.
I feel though that giving friends free advice over something like this is cause for concern. I'm more confident about a friend replacing a load bearing wall in their house with a beam than I am with them building a covered patio that won't fall down.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
Before the pile-on, please give this a thought: When did you last get free advice from a Doctor? Lawyer? Free advice reduces the value of our knowledge and harms all of our fees.
An hour's work for an hour's pay. Where your buddy is doing something for you in kind, fine, but don't engineer for free.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.
RE: how to assume drilled pier skin friction and lateral capacity for patio column. no geotech.