Help finding a toilet flange under cement

[Dave Sparks]

Could use some advice on how to find a toilet flange under an inch of cement. I have been drilling in the places where it should be and I am not finding the little sucker? It is 3" abs with the flange and cap. I tried to whitch it but I am the wrong sex? Any ideas?

[PEG688]

Gentle tapping on the concrete in the area you think the flange is in. There will be / should  a hollow tone/ different sound  to the concrete directly over the flange. 

[Redoverfarm]

My first though Dave is like Peg explained.  To witch it you will need water in the line.  Have found plenty outside but never tried to inside under crete.  Of course they make a "high tech" instrument that you insert through the exterior which gives a signal and using a sensor on the top side it will pick it up.  Good Luck

[firefox]

If you can get at a port on the other end, introduce some loud
noises into the pipe. A boom box comes to mind with some of this
weird music they play nowadays. Then just use a mechanics stethescope or a cone made from cardboard to locate the noise on the floor.
Hope that helps.
Bruce

[MountainDon]

As PEG said. The floor 'thumps' different.

[bayview]

   Next time around you may want to extend the pipe 16-18" above where the concrete will be finished.   Cap the top of the pipe.   And wrap a couple layers of cardboard around the pipe where it will meet the concrete.   

   After the concrete is poured you can cut the pipe, fill the gap with caulking and then install the flange.

/.

[glenn kangiser]

Fastened with nails or screws or have a metal ring on top, Dave?  You could let your neighbors know if that might be the case and they could bring a metal detector over....

[Redoverfarm]

Dave I talked to BIL who works a lot around concrete (dams) and he suggested that you use a metal rod or rebar about 3-4' long.  Holding the rod in the verticle position 6-8" above the area and letting it drop striking the floor.  The rod will transfer the sound better.  Repeat the procedure until it cast a different ring.

[considerations]

Rotten!    The silver lining is I'm noting the suggestions in case I do something like this in the future.

[JRR]

If you can catch the sun out, try soaking the slab evenly with water ... the thinnest concrete should dry out first .... displaying the flange location.

[Dave Sparks]

Thanks everyone! With the three day weekend coming and my brother-in-law buying all the beer we are going to try everything here except the thumping on the concrete. That did not seem to work for me.

This was done on purpose BTW. Boot leg a bathroom to keep Glen's pesky inspector from being an issue.
I have pictures and distances, and quite a few drill holes

[firefox]

Thinking ahead on this type of problem. Before pouring concrete
take 4 nails and two lengths of chalk line. Put the nails in on the
plates on opposite walls so that when you secure the chalk lines
to them they form an X over the drain. remove the chalk lines,
pour concrete, then reinstall chalk lines on the nails, and X marks the spot.
Bruce

[glenn kangiser]

Thanks everyone! With the three day weekend coming and my brother-in-law buying all the beer we are going to try everything here except the thumping on the concrete. That did not seem to work for me.

This was done on purpose BTW. Boot leg a bathroom to keep Glen's pesky inspector from being an issue.
I have pictures and distances, and quite a few drill holes

I think we have the inspector under control now, Dave -- contractors association tarred and feathered the last one and I think the new one pretty well gets it from what I hear..... still on the QT though.

Dave - a bit of gentle tapping with the 4lb sledge and a trained ear should really find that pipe..... [ouch]

[Dave Sparks]

Gentle tapping on the concrete in the area you think the flange is in. There will be / should  a hollow tone/ different sound  to the concrete directly over the flange. 

This worked well with a big, big hammer and not so gentle tapping! Thanks Peg and all the others that I did not have to try. I was off in my measurement by two inches. There won't be much for my brother-in-law to do on labor day except drink my beer Maybe split some unseasoned oak..

[glenn kangiser]

Cool, Dave .  I hope everything comes out OK.....

gottogo