I am looking for a practical way to find metal posts location in a finished basement walls or finished ground floor walls. I am trying to understand how my house was built. I would like to remove a wall to make an open concept kitchen & living.(pictures below). Cathedral ceiling in the living might be an option

How do I find out where the steel posts are located? The same question goes for any horizontal steel beam that might be installed in a house. My house is a bungalow, rectangular shape (25'x47') The trusses look like this:

enter image description here

Apparently the roof sits on the exterior walls only but I suspect that there must be some bearing beam on the ground floor

Here is where I am driving with this investigation http://i.imgur.com/tLZewWH.png The diagram was created when I did not have access to the house, but now I know what the trusses are like.

  • Pictures of the actual house? What country? Why the need for extra steel if this is a framebuilt house as the perimeter walls would have enough strength to support truss or joist and rafter roof? Dec 21, 2014 at 22:02
  • Country is Canada. I think that the basement needs that beam. As you can see there is a quite large area opened in the living and the rafters are not that long and solid to support everything over that area hence my uncertainty. It might actually be just like what you said ..but I need to make sure. How do I do it?
    – MiniMe
    Dec 21, 2014 at 22:58
  • Are all the trusses the same ? And they span a open area already ? If so walls may not carry heavy load. Making new roof bit of work. Your wall in basement is holding up beam. Ya some lolly post.
    – user101687
    Jun 14, 2019 at 3:28

3 Answers 3


Use a compass. The answers that suggest using a magnet are on the right track, but if the steel is embedded just a couple of inches inside the wall, there won't be much "pull" on the magnet.

A compass will swing dramatically as you move it past deeply embedded structural steel. I've done it and it works.


To find a metal post, I would try using a magnet. The stronger, the better. A massive speaker magnet in hand should give you an indication what is where. (Warning: strong magnets can BITE!)

  • he he ...I thought about that too but I think that these days most of the speakers are build using solenoids. How big would you recommend the magnet to be? How about a stud finder...there is a model with some deep sensing for finding electrical wires.
    – MiniMe
    Dec 26, 2014 at 14:48
  • A magnet out of an old microwave magnetron tube is strong these are some of the strongest magnets I have found.
    – Ed Beal
    Feb 14, 2019 at 14:26

The magnets I have are about 4" wide.

Yes, if you want to spend the money, they have some good stud detectors that allow you to "zero out" everything but what you are looking for (depending on where you place it when zeroing it).

My boss just got a endoscope type camera that's about 3' long that you can use to look around behind walls and such. He got it at Harbor Freight for about $80. You could even use one of those.

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