[TowerTalk] Finding roof beams

[Bill Coleman AA4LR]

On 6/26/97 11:09, Flanders, Jim at jaf00@aag.com wrote:

>Determining the location of roof beams:
>So some of the tools I bought ... are ultrasonic stud finders.  
>[...]
>After a recent post, I went on the roof between the 
>thunderstorms here in Texas and tried it for finding
>roof beams.  The $19.95 variety could work eventually, but it is very 
>frustrating and time consuming because of the var-
>iations of composite shingle thickness. 

WARNING! 

Even the $20 ultrasonic stud finder can lead you astray. The stud finder 
merely finds the densest part of the wall.

Here's a story: I was putting up a quilt hanger for my wife. I had these 
great wall screws that needed to go into a stud. The hanger required me 
to carefully space to clips that went over the wall screws.

So, using my ultrasonic stud finder, I marked out the spacing of the 
studs in the wall. Since it was an outside wall (filled with insulation), 
the studs weren't very pronounced, and there were some false (weak) 
readings. Studying the marks, something didn't seem right, but I picked a 
couple of studs and proceeded to drive the screws into the wall.

The first screw acted rather strange. It went through the sheetrock ok, 
but then hit something. Since I was using an electric screwdriver, I 
applied a little pressure, and the screw went into the wall as easy as 
you please. 

Once the screwdriver was off, I heard a faint sound - "sssss". After a 
moments thought, I backed the screw out a half-turn. The sound turned to 
"SSSSSSS". I took the screw out. The subsequent rush of gas out of the 
hole in the wall made a tremendous noise, and I quickly got everyone out 
of the room.

The ultrasonic stud finder had lead me unerringly to the densest object 
in the wall -- I had punched a hole directly into the copper tubing for 
my upstairs heat pump. Someone commented that I couldn't have put the 
screw more squarely into the tube if I had measured it. 

(Tube was fixed the next day. It was a cold night upstairs that night. 
(Big) hole in the wall was fixed the next week. Quilt hanger wasn't put 
up for another 2 months.)

So, before you anchor anything to a "stud" in the wall found with one of 
these stud finders, make sure you know what you are fastening to.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Not in a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:			  http://www.contesting.com/km9p/search.htm