There are metal detectors specifically tweaked for detecting rebar and post-tension cables in concrete.  The cheapest I'm aware of is the <span class="Apple-style-span" style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 13px; background-color: rgba(255, 255, 255, 0.917969); ">Zircon MT-6 @ ~$125.  It's good to 5-6" depth.  I assume there are more expensive models that look deeper into the concrete.</span><div>
<font class="Apple-style-span" color="#222222" face="arial, sans-serif"><br></font></div><div><font class="Apple-style-span" color="#222222" face="arial, sans-serif">You certainly don't want to go near a post-tension cable as cutting such a cable could seriously reduce the structural integrity of the building.<br clear="all">
</font><div><br clear="all">Thanks,<br>Brough Turner<br><br>Mobile: +1 617 285-0433   Skype: brough</div><div><span style="color:rgb(136, 136, 136)"><a href="http://broughturner.com/" target="_blank">Website</a> | <a href="https://plus.google.com/102447512447094746687/posts?hl=en" target="_blank">Google+</a> | <a href="https://twitter.com/#!/brough" target="_blank">Twitter</a> | <a href="http://www.linkedin.com/in/broughturner" target="_blank">LinkedIn</a> | <a href="http://www.facebook.com/brough.turner" target="_blank">Facebook</a> | <a href="http://blogs.broughturner.com/" target="_blank">Blog</a> | <a href="http://www.netblazr.com/" target="_blank">netBlazr Inc.</a></span></div>
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<br><br><div class="gmail_quote">On Fri, Dec 9, 2011 at 10:33 AM, Stephen Ronan <span dir="ltr"><<a href="mailto:sronan@gmail.com">sronan@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">> I gather a metal detector wouldn't help due to rebar? If you just needed<br>
> to detect live power lines, there are tools that can help with that.<br>
><br>
> Is the building so old that a review of the blueprints would be<br>
> impossible or insufficient?<br>
<br>
</div>I'm wildly guessing the building dates to around the 1970's. For<br>
reasons I don't understand the GPR person was very dismissive of<br>
the possibility that a review of the blueprints would adequately<br>
address the problem. From what I read, "post-tension cables"<br>
seems like a significant potential issue; I don't have a sense of<br>
whether there'd be another way to determine their location.<br>
<span class="HOEnZb"><font color="#888888"><br>
Stephen Ronan<br>
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