"Larry Johnson" wrote in message
...
We have a woodburning fireplace we are converting to gas logs. I am trying
to drill a hole to accommodate the gas pipe through the floor in a front
corner of the firebox to a utility space under the house. I get through
the firebrick, about 3 1/2", and then hit something my carbide bit cannot
penetrate.

Does anyone have a suggestion how to detect what I'm hitting? Do they use
steel plate reinforcement in fireplace construction? Any help is
appreciated.

there was a steel plate in the top of mine. can you look at some
shavings/dust coming out of the hole to see what it is? reinforced concrete
(you hit rebar)?