I’m considering underpinning the perimeter stem and stepwall foundation (hillside)for a ranch to allow increasing the footing to handle a 2nd (1/2) story addition. My question is that in looking at the local code tables I need an 8″ thick foundation (2 X 4 walls currently) and I currently have a 6″ wide foundation thickness. If I underpin, that will only increase my footing depth and width, but will do nothing for the foundation thickness. So what can be done or am I missing something? Also, when you underpin, I never see any mention (in threads) to how the old footing is tied to the new one below.
Thanks
Ron
Replies
Ouch!
i'm not sure I understand how you are using all these terms.
What is underpinning?
by foundation do you mean the footing?
if my guesses/interpretations are right, you belive you need to increase the thickness of your footings to 8" elevation wise, and the width of you foundation walls from 6" to 8" horizontall measurement. You base trhis on reading your local code. if that is right, you would probably need to jack the house and rebuild the whole thing.
But
The code shouold also be saying that altrernatively, the foundation should be capable of handling a certain load per sq ft, or that alternatively, they would accept the determination of a civil engineer relative to soils and your existing foundation in lieuof the standard for new construction.
Given that, the cost for an engineer's assessment and recommendations WOULD BE CONSIDERABLY LESS THAN REPLACING THE FOUNDATIOPN
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
The parts of the question left out leave me with only one reply:Hire a foundations engineer.
...that's not a mistake, it's rustic
I am surprised at Piffin & the O'poster....what you haven't addressed is if your existing FOOTER might not be sufficient...and unless you dig out a section, who knows....
Sadly, you are probably in a grey area....where it's going to be entirely up to the local inspector to decide what he wants....I would have no problem adding a second story to a good solid footer +6" stemwall (block I'm assuming) since there are probably millions of existing homes sitting on just that...if you can't get an engineer or a local permit office to sign off on that, then the Other Posters are right, it's a jack job most likeley
I suppose you could add 2' solid block to the existing 6" stemwall & maybe some bureaucrat would like it, but what would be the point?
I did adress that, by suggesting that he hire an engineer to determine whether the existing would suffice or what might nee to be done to make it right.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Looks like I will have a structrual decide my fate.
Thanks.