How do I determine whether pipes (water, electricity, gas) are buried in basement concrete?

Question

I would like to drill two 2.5″-deep holes for 5/8″ bolts (64mm x 16mm) in the basement floor. The two holes will be used for a (bicycle) floor anchor.

How do I determine whether pipes (water, electricity, gas) are buried in basement concrete?

Most critically, there is a gas line that runs from one corner of the basement to the heating furnace in the other corner. I can see that line overhead, resting on the wooden beams. Does that mean there won't be another line buried?

As a last resort, is there much safety to be gained from drilling 1mm, vacuuming, and inspecting, before drilling again?

Answer 1

In my limited experience, the only things I've seen buried in basement floors have been the lines from oil tanks to burners (so the burner can be gravity -fed from the tank). Those run thru either conduit or some form of hose, and in my area you can often (but not always) see a cutline in the slab from when this was installed. There are ways to trace this line, basically by hooking it up to a transmitter and using a short-range receiver to track the resulting "antenna). I don't know whether the "Dig Safe" folks will do in-basement tracing or if you'd need to hire someone or buy the equipment.

I got rid of my oil heat, and all the other utilities go thru walls or ceilings. That doesn't guarantee nobody did something "creative' on your property.

Answer 2

Whether there are any pipes embedded in the concrete depends on building style & type of building. Usually, in a North American house built of wood on a concrete foundation, the foundation and slabs are poured after the drain/sewage and water service entry since they have to be below the frost line, and everything else is completed afterwards. A slab is usually 6in thick, and the top of pipes underneath it may touch the bottom of the slab.

So look around the basement, trace all water, gas and electrical lines: if it's underground and embedded there will be an exit/entry point somewhere.

That's the speculation part. Now to the specifics of your question:

How do I determine whether pipes (water, electricity, gas) are buried in basement concrete?

• obtain building drawings. These may be available from previous owners or the city
• perform a concrete scan. There are specialized services that perform just that for any drilling: they look for gas, water, electrical, other plumbing, rebar and tensions lines, which are common in concrete structures.

is there much safety to be gained from drilling 1mm, vacuuming, and inspecting, before drilling again?

If you puncture or scrape the pipe or jacket it's too late. So unless you know it runs in a sleave this approach is not effective. This might work if you have better visibility and for that you should use a wider drill bit. Also requires a degree in archeology.

will be used for a (bicycle) floor anchor

Unless you are close to the exit point of such a line, which you would see, it is very likely that the lines are at least 1in buried. SO you could roughen up the concrete, and add a cement build-up for the anchors. Or use adhesives for a wooden base, and screw into the base.

Answer 3

I have one of those metal and electricity detectors. Works very well.

It even finds the single drywall screws.

I tested it on a wall where I already knew the mains cable was so I knew how it behaved, this was also how I worked out that it was finding screws…