huangyhg

scanning for structural steel
does anyone know of a device that can locate structural steel behind drywall? for example, conventional steel framed building with gwb walls to the underside of the spandrel beams, therefore can not see diagonal braces. is there some device that can detect the braces? or am i going to have to poke holes in every bay of the building to locate the braces. i thought maybe infrared thermography might be able to locate them. or maybe ground penetrating radar. i don't think a metal detector will work due to metal studs.
any ideas?
there are some "stud finders" that will see metal.... available at any big box store for under $100.
some one also makes a mini-radar device that will "see" metal.. not sure who makes it - but have heard it is great at finding rebar, studs, etc. try google.
infrared thermography won't do it. you need a good temperature differential for that to work, and what you've presented doesn't reflect a differential temperature potential.
use a borescope or a stud finder as noted. the borescope only requires a small hole (mine requires about 5/8 of an inch. some have photographic documentation capability which is good for your files.
i have had success in the past using a relatively inexpensive rebar covermeter such as the protovale rebar plus in similar situations (there are many much more expensive models). you can usually detect rebar to a depth of about 6" in concrete and i would assume that you could detect structural steel up to a similar depth. use the audible signal for detection and ignore the depth/cover reading on the machine, it will not be accurate with structural steel. first i would locate two vertical studs by scanning horizontally then scan vertically inbetween the two studs for diagonal bracing. by doing scans between adjacent studs, you should see a pattern emerge if you are detecting the diagonal bracing. you will have to perform some test openings at a percentage of the locations to confirm your results.
potential problems ... if the vertical studs are too close together, they will interfere with the detection (a 16" stud spacing should work well). also, any horizontal bracing for the studs will interfere, thus you are looking for the diagonal pattern in adjacent stud spaces. equipment such as recommended above is relatively expensive but sometimes can be rented in larger cities (check with the manufacturer) or concrete testing labs usually have a few kicking around.

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