Increase Very Old Undersized Footing
Increase Very Old Undersized Footing
(OP)
I have a 4 story residential building with a very small footing built in the 1920's. The footing size is 16" wide x 5" thick. Is underpinning it with a larger footing the only "practical" way to increase it in width. The major problem is the building has been totally renovated and its at the end of the bank financing it. The Architect never required the existing footing to be checked. The buildings stucco and brick is cracked like a road map. I got the job to inspect it and remediate from the owners lawyer. Any tips will be greatly appreciated.






RE: Increase Very Old Undersized Footing
Mike McCann
MMC Engineering
RE: Increase Very Old Undersized Footing
RE: Increase Very Old Undersized Footing
RE: Increase Very Old Undersized Footing
You could use pin pile - 2 " diameter - per a geotech recommendation at the exterior continuous footings, and underpin any interior strip footings periodically along the footing.
Mike McCann
MMC Engineering
RE: Increase Very Old Undersized Footing
DaveAtkins
RE: Increase Very Old Undersized Footing
Resistance or Push Piers on a building thats looks ready to collapse and is already a lawsuit against the Architect?? I don't think so.
RE: Increase Very Old Undersized Footing
I"ve been involved with a few projects that have been standing for the better part of a century and the foundations have been somewhat undersized.
Just some ramblings...
Dik
RE: Increase Very Old Undersized Footing
The building is 90 years old and the owner is looking to get another 40 years out of it. The 12" brick walls have no lime mortar left in their joints and the rear wall is on the verge of collapse. Something has to get done ASAP.
RE: Increase Very Old Undersized Footing
Is there any heritage value to the building and any heritage restraints?
Also SlideRuleEra has a pdf paper on historic masonry that I prepared. You might want to take a gander at it. If you are planning to maintain the original masonry, you have to examine the issue of vapour barrier and existing mortar. In old buildings, vapour barrier is not often used and the wall relies on the mortar to 'wick' moisture from within. In addition, modern lifestyle creates a lot more humidity within a building. Someone (architect?) should look into this.
Often damage is done to old buildings by a lack of understanding on how they function.
Dik
RE: Increase Very Old Undersized Footing
You could also underpin the footing with alternate concrete piers - that is, maybe 4'w x 3' piers spaced at about 8' on center or closer. This would provide at least the same bearing area, but hopefully at a deeper elevation with better bearing capacity.
However, whatever method you chose, there is the probability that the building will experience some additional settlement and damage. Therefore, you want to make sure the owner is aware of this and that you are not responsible.
RE: Increase Very Old Undersized Footing
RE: Increase Very Old Undersized Footing
Why not resistance piers? Isn't that easier than concrete underpinning? And perhaps better than helical piers.
DaveAtkins
RE: Increase Very Old Undersized Footing
Any piles you can do would likely need to be so close together (because of the 5" thickness of the footing), unless you can assume the wall itself will span between piles and not count on the ftg to do the work, that you will be essentially performing an underpinning operation with piles.
Just underpin it.
RE: Increase Very Old Undersized Footing
RE: Increase Very Old Undersized Footing