Detect RSJ

Hoping someone can help with the following-
Is there an easy way to detect whether an RSJ has been installed or does all the plaster board around it have to come off? One of those little laser like gizmos perhaps? I installed it and so know it's there but there was no architect's involved, so no certs, and I want to sell now and am wondering what is involved in proving it's there.It's a weight bearing wall and it was done in '96, so there is no problem with it as such

A reasonably strong magnet should do it

The magnet/stud detecors will just tell you it's there, but you already know that. So I'm guessing is that you need a cert of compliance to sell? You'll need to engage an engineer and get their opinion.

You might be able to get something to detect that it is there but what you need to do is show that it is there, correctly sized, in proper condition, and properly located/installed.

To be honest, removing some plasterboard is probably the easiest way to do this.