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Makin’ more holes

December 3, 2010

Over the last week, more holes were needed. But I wasn’t in charge of them – our HVAC contractor hired a subcontractor to core drill all of the holes they needed for getting hot/cold air everywhere, some drain tubes, and the exhaust ducts for bathroom and dryer vents.

They wanted my input on the exact locations so since I was down there already, I took some pictures & video.

Here is the setup of the rig for the larger hole in the floor:

Drill rig ready to make 10" hole

Since this hole was the biggest they were drilling, they wanted my “approval” on its location. While we don’t have any structural drawings of the building, based on my professional experience and the work we’ve done on the building so far, I guess-timated that there was steel in the concrete floor along the wall. I also guess-timated that the next steel location was right about where they had the outer-most edge of the big black core bit.

I asked if they could move the hole towards the wall by about 5″; but the HVAC contractor needed to check if that new location would still align with the duct equipment that is already in place above. (Not visible in that photo.) In his opinion, No. So I asked them to just move it in a little bit, which was maybe an inch.

I went to the basement to watch the drill come through the floor. Here’s a link to a short video (1 minute) on YouTube: Click here.

Near the end of that video, one of the drilling guys yells “Hey is that wood?” From his angle it may have looked like it, but no, I could tell – they cut sideways through some of the reinforcing steel. After the water flow stopped, I looked closer – a few inches away they’d cut through a second steel rod.

While not ideal, having them cut through this steel isn’t disastrous. The floor will be fine for our regular use, but if we ever put an increased load on it, like support a mezzanine floor above it, then we’ll need to reinforce it from below.

The bummer is, that if they had only been able to move the hole over 4 or 5 inches, they would have missed both pieces of reinforcing steel!

I almost bought our own core drilling rig at one of those commercial auctions I go to – but I was outbid. After watching these guys, right now I’m glad I DON’T have the core drilling machine. It looks like it takes some experience with knowing how fast to spin the drill, how much water to pump through the drill for the right lubrication, and how hard to push down the drive spindle.

In addition to that big hole, they had to drill about ten small holes around the perimeter of the Living/Dining room which would be supply air vents to that space.  The night before, I’d removed the plywood protection around the edge of the room so that they could use their vacuum pad to anchor the drill vs. boring an anchoring hole with a bolt. The nice polished floor was perfect for using the vacuum method.

Here’s a photo of their setup for the small holes:

Air holes at the Dining Room

The vacuum pad is that silver-colored disc on the floor (just in front of the guy’s toes), and the drill is mounted to the top. It holds a suction on the floor, so when they push down on the drill to start cutting, the suction provides the push-back reaction against the floor. The little machine in the bottom of the picture is the vacuum pump.

If you watched the video clip above, you’ll remember LOTS of water flooding through the big hole. Since these guys knew these small holes were in a finished space, the second guy is standing behind the drill guy with a wet-vac and sucking up all of the water that they’re using for lubrication. It was a much cleaner operation.

Lastly, they had one other hole to make – a 2″ diameter hole through the second floor to run their refrigerant lines up to the condenser on the roof. I directed them to locate it near the plumbing vent that had the same objective.

The project manager for the HVAC job came up to me with a concerned look on his face and handed me this odd little piece of steel:

Folded steel?

He didn’t say much other than that they were drilling in the second floor and then found this. It kinda looked like a rolled-up disc of steel, almost like a fortune cookie. I puzzled over it for a few seconds and asked “What orientation was this?” I couldn’t tell right away if it was horizontal, vertical, rotated, etc. He took it back from me and held it in another orientation, like I am holding it in the next picture. I’ve added a dashed line to show you how a 2″ drill would have encountered this piece.

Imagine a 2" hole...

So what this IS is actually a PIPE of some sort! Embedded in the second floor. And the guys just severed it.

Unfortunately, it is most likely a gas pipe – in the early 1900’s, they were still using gas for lights (instead of electricity) so just like we run electrical wires inside of our construction today, when BAB was constructed, they would run gas lines within the walls, floors and columns.

Fortunately, it’s in a very old part of the building, so there is a possibility that this line has already been abandoned and is disconnected from the gas supply.

Unfortunately, the ONLY way we know of testing it is to just turn on our gas (it’s currently off while we’re under construction) and then just put a good sniffing NOSE where they cut the line and then tell if we smell gas!

And sorry if you predicted another “Fortunately”… if that gas pipe IS still connected, it’s going to mean some demolition to the floor slab so that we can expose enough of the pipe within so that we can thread and then cap off the line. Yuk.

Overall, we are very happy with the hole-drillin’ guys work; they were neat and respective even though they had a very potentially messy job. They were in and out of BAB in a day and a half – and they did a great job.

One Comment leave one →
  1. Mike-n-Stef permalink
    December 7, 2010 7:15 am

    You can test to see if that line is abandoned by pressurizing your gas line. Since the gas is distributed through a closed system, if the system holds pressure then that pipe has been abandoned. If you have some pilot lights you might lose a small amount of pressure – so don’t super-pressurize it, as you won’t want to damage the pilots.

    When you have the system pressurized you can “listen” to that hole to see if you hear hissing air.


    (Typed by Stef as Mike dictated…)

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