MoreCowbell

Hello. I mentioned in an earlier post (http://www.houserepairtalk.com/f39/new-amateur-project-11441/) that I plan to dig my crawlspace a bit deeper. I have several masonry columns that I need to replace in order to rebuild their footings at a deeper level.

My initial plan was to duplicate the existing footing dimensions. However, I got to thinking that if I go with steel pipe columns do the footings need to run deeper due to the weight being concentrated on a smaller footprint on the footing? The current masonry columns are 16" square which distributes the load over a larger area on the footing.

Am I overthinking this or do I really need deeper footings for steel coulumns? Thanks.

RocLok

Looking at your other post, it looks like you have a lot more than steel VS concrete going on. If the old foundation was built on dirt that you are removing, that is not good. First thing is to make sure to shore up any areas that you are modifying.

Due to the fact that you are risking the loss of your house completely you will definitely need to talk to an engineer and figure out how to hold your house in the air after you remove it's support. Look at it this way, it may cost you a few thousand dollars to have an engineer help you, or it could cost you your house, your possessions hopefully that is all if you do not support it correctly.

Good luck,

-Ryan

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MoreCowbell

Thanks for the reply. I'm actually not modifying my existing foundation. I'm digging the crawlspace deeper while staying away from the existing footings a safe distance so as not to undermine the footings. I did have an engineer look at it, and he said I need to stay clear of the 45 deg. slope from the bottom edge of the footing. In most places, I'm staying away even further than that just to be safe.

He also told me to duplicate the existing column footing dimensions when I install the steel posts. However, I'm wondering whether the narrower steel columns require a deeper footing than the wider masonry.

nealtw

In houses built today you find a footing for a post is about 30" square and 10" deep with 3 rebars going each way, then you build small curb to bring it up to floor level, something about 8" square with steel tied to the lower steel, in the wet concrete you can place the ancher bolts for your post. Aways put something water proof between concrete and steel or wood. Now run all this past the engineer, he should check your soil condition before making his final call on footing size. When in doubt keep in mind that concrete is cheep so go big.