Rotary Hammer

Between the basement, the patio in the back yard, and potentially even the garage pad, we have a lot of concrete that we may dig up at some point. Enter my newest toy: a rotary hammer. This thing drills through concrete the way a normal drill goes through wood. I also got a chisel bit for it (see the photo), which works like a miniature jack hammer.

Corner in the Basement

The first task for this new kit was to find out how deep our footings are. I’ve been meaning to do this for a few months and it will answer the pressing question of how high our basement ceiling would be if we excavated the floor. I picked the Southeast corner, mostly because our convoluted, multi-phase plan to live in the house while we renovate it will lower this section of the basement first because it will become the utility room. That complicates other initiatives like moving the washer and dryer to the basement, but we’re taking some things a step at a time.

Perimeter holes

With minimal fuss I drilled enough holes through the floor to start chipping away the hunk of concrete. I’ve since gotten a good circular saw and a masonry blade so that this can be done more cleanly, but this way works too. The one advantage this method enjoys over using a saw is that there was very little airborne dust. Instead I got neat little piles like ant hills.

Chiseled Edge

The next step was to use the chisel bit on the hammer-only setting to connect the dots and separate the section from the rest of the floor. As soon as that was one done I reached for my trusty sledgehammer. Wait, I don’t have a sledgehammer. Ok, so I went to the hardware store and bought a sledgehammer, along with the previously mentioned circular saw and blade (just in case). A few good whacks and some prybar work freed the hunk of concrete and the result was dirt.

Hole. Also pictured: trusty sledgehammer

Then the fun of digging out the dirt began. Fortunately, Sarah offered to take this task and quickly excavated the footings all the way to their base. When she was done I went down and used a tape measure to see what we had.

Checking Depth

The result? An unsurprising 12″ of footings under 2″ of concrete floor. That’s a total of 14″ we can dig down, but then we need to fill back up 2″ of gravel and then 4″ of new concrete. That means we’d gain 8″ of height for a total of 7’4″ ceilings. Unfortunately, we need 7’6″ by Chicago code to consider it finished space.

That gives us three options: don’t finish the basement (at least on paper), underpin the foundation (massively expensive), or just skip the 2″ of gravel. My inclination is the third option, though the first might save on property taxes. On the other hand, the gravel may be superfluous given the age of the house and where the water table is. We’ll bring back our foundation guys to give us a quote and discuss the options with them.

 

3 Responses to Getting a Footing

  1. I hear dirt floors are all the rage now.

  2. heh heh heh, roto hammers kick ass!

  3. Matt, here is another item to keep in mind while thinking about the “finished basement” option:

    You would need to insulate under the new concrete floor with a minimum of 4″ of XPS insulation to get to a R-20. Skipping the insulation would create an energy drain and make it hard to create a comfortable environment in the “finished basement”.

    http://delafleur.com/blog/?p=1063

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