Demo stemwall, leave footing and slab
davidmeiland
| Posted in Construction Techniques on
Job coming up requires that we remove about 24LF of 8″ x 16″ stemwall under the side wall of a garage. The garage is getting expanded by one bay, so we’ll be leaving the existing slab but removing the stemwall that projects above it and then extending the slab past that line.
It’s easy to imagine chipping or cracking the existing slab. I’m tempted to have my excavator go after it… seems easy but risky. I loathe the idea of jacking that much concrete by hand, but maybe that’s the way.
What’s the smart way to surgically remove the wall and leave the slab untouched? I have no access to concrete cutting companies or any good stuff like that.
Replies
If it has no vertical rebar in it it will probably come off the footing pretty cleanly. Unless is was a monolithic pour, the stemwall probably meets the footing with a cold joint albeit with a keyway.
If you get an excavator (ideal would be a small one with a jackhammer attachment), the risk would be dislodging the footing and getting fractures migrating into the slab you want to save.
A small stemwall like you describe might be a fairly simple removal with a jackhammer, especially if you can rent a big one with a large compressor to power it. Those small, electric ones, like the Bosch, might be a PITA, especially if you have to run them somewhat horizontally.
You should be able to rent a concrete diamond saw (like the chainsaw motor type) to score it both sides and knock it apart with a big sledgehammer.
I did a similar thing a few years ago; actually tipped the footing over with a small tractor with a bucket far enough to expose the rebar which I cut off with a torch.
You might get lucky!
The typical detail here is two pours, footing then wall, with rebar poking up out of the footing to tie into the wall. If it was done mono then the steel is the same and there isn't a cold joint.
I was wondering about the feasibility of some sawcutting. The rental place has the Stihl chainsaw-lookin' concrete saw that you can connect a garden hose to. I don't know what the depth of cut on that is, but it probably isn't adequate to cut thru a 6" or 8" stemwall from one side.
I don't think they have a pneumatic jackhammer but I'll check that out. My excavator has a rock hammer for his machine, or at least I think he has one that fits the compact machine.
The Stihl saw probably has a 14" blade which allows you to effectively score about 5 to 6" deep on each side. Of course, you won't be able to cut flush to the slab or footing, but it will help. You'll still have some jack hammering to do....
The hammer on the excavator would probably be my choice if it's available....after the wall is broken out, he can exchange the tip for a bucket and remove the debris.
Cost of the excavator will probably be a wash with doing a lot of hand work and one heck of a lot easier.