Residential Footing Assessment
Residential Footing Assessment
(OP)
I have a family member who owns a ranch home. She would like to add a second story. She knows what I do and asked if there are any problems withthe idea. I told her thatit can certainly be done, it's just a matter of how much work will need to be done. As far as I can tell, she's not required to have an engineer, but I told her I would at least put my eyes on it.
This leads to the question - how do you assess the footing(s)? The structure and even the bearing pressure for the footing is pretty straightforward. Would you get a metal detector and try to locate rebar I'm the footing(s) - both spacing and depth?
I'm sure this kind of thing isn't uncommon. Are there any guidelines out there somewhere? Does this typically require underpinning? What would be the standard of care here, even though it's not a "project" in the typical sense
This leads to the question - how do you assess the footing(s)? The structure and even the bearing pressure for the footing is pretty straightforward. Would you get a metal detector and try to locate rebar I'm the footing(s) - both spacing and depth?
I'm sure this kind of thing isn't uncommon. Are there any guidelines out there somewhere? Does this typically require underpinning? What would be the standard of care here, even though it's not a "project" in the typical sense






RE: Residential Footing Assessment
As long as the concrete footing has enough depth for a 45 degree spread from the edges of the wall and has enough width for the required bearing then I would think it would be only serviceability concerns (e.g. heave e.t.c.) that may cause problems.
These issues would depend on the soil.
RE: Residential Footing Assessment
If the house is older, chances are 99/100 that:
- The footing was never designed in the first place, generic builder variety
- depending on old local codes, there is no bar/minimal bar in the footing
- the exact same footing that is there, would have been used for a two story house.
RE: Residential Footing Assessment
Lion 06, if the bearing stress is okay and there are no signs of distress than thats 90% of the issue.
RE: Residential Footing Assessment
RE: Residential Footing Assessment
RE: Residential Footing Assessment
RE: Residential Footing Assessment
For an 8" block wall
Builders typically use a 8"x16" ftg
12" block, usually 24" wide
I'd be shocked if there was any issues at all.
RE: Residential Footing Assessment
RE: Residential Footing Assessment
RE: Residential Footing Assessment
Thanks again, guys!
RE: Residential Footing Assessment
If looking to investigate footing depth & width, excavating a small area in the basement is probably cheapest.
Again, 99% wouldn't even give the footings a thought.
RE: Residential Footing Assessment
RE: Residential Footing Assessment
If you add additional structure above one segment of the house but not the other, you do pose a risk of this differential settling and distress cracking between the two areas.
RE: Residential Footing Assessment
RE: Residential Footing Assessment
Lion- you could orient the floor joists of the addition opposite the first floor (if the walls have the proper headers) ...maybe the same for the roof. That way you could load the basement walls more "evenly"
RE: Residential Footing Assessment
Look at the performance of the existing walls/foundation. If no apparent distress....not likely an issue.
RE: Residential Footing Assessment
That will give you a good idea of the footing size. Use the 1500 psf capacity and re-check the calcs. If the house is not so wide and no brick involved - you will probably be OK.
Done all the time.
RE: Residential Footing Assessment
Also realize that the load applied to the top of the basement wall will be somewhat well distributed by the time it reaches the footing. Even on gable ends of a house. The wall is a deep beam that will spread the load over a large area.
RE: Residential Footing Assessment
But there are lots and neighborhoods where it is worth it.
RE: Residential Footing Assessment
RE: Residential Footing Assessment
I assume that this ranch house is not a log structure? If so, then the only concern with the code might be a local need for a n 8" wide stem wall rather than the typical 6" stem wall. You might have to show that a 6" will work. Been there, done that.
If the stem width is only 6", then the footing width may only be 12", limiting the total load to 1500 plf.
You'll need to check it out.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Residential Footing Assessment
RE: Residential Footing Assessment
are the joists pocketed in the masonry?
RE: Residential Footing Assessment
RE: Residential Footing Assessment
Another first step might be to get the Agriculture maps of the area and see what the soil types are there - I found them quite interesting in the field next to my mum's place in Indiana.