sensing wall studs through tile over plaster and lath.

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perfectbite
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sensing wall studs through tile over plaster and lath.

Post by perfectbite »

The little Zircon stud finder I have says that the varying densities of the plaster 'squozed' (a new word) through the lath slats won't allow the device to give a good indication of a stud's location. The house was built in 1911 way before plasterboard and this is for a shower grab bar for an elderly stroke victim so it is kind of important that it land on the full 2" wide 2x4 stud.<p>If I slide a microphone across the tile while gently tapping the tile at the microphone's location with a plastic hard faced mallet and listening for the returning differences (like sonar/ASDIC in a multi layer solid) would that work? I'm assuming that interpretation of the resulting sounds give will useful information. How could I, simply mind you, select and compare, out off the reflected sound spectrum, just those sounds I think indicative of a stud's location.<p>This idea and a stucco 'sense through' sensor DEFINITELY have commercial applications and certain areas of the country would snap up working devices like this and pay well for them. I however just have this one job and would be happy to field test a stud finder prototype for you or rent, for a reasonable fee, a truth telling, under tile and plaster and lath, stud finder or breadboard a simple one time prototype.<p>Otherwise can anyone suggest a simple, initially referenced, amplification circuit to do the trick? There may be closed void echoes and using a stethoscope could be hit or miss. Dull 'thunks' versus hollow 'thunks' with possible echoes and the 'ring' of the tile in both? I couldn't easily or quickly seperate out those sounds. Perhaps someone with a golden ear could. Logically, 2 horizontal linear inches of absolutely no primary echo would give a stud location. For a towel rail it wouldn't matter. <p>Thanks<p>[ July 28, 2004: Message edited by: perfectbite ]</p>
Ron H
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Re: sensing wall studs through tile over plaster and lath.

Post by Ron H »

You may have already done a search. If so this is old news.
The DIY sites on the Internet recommend using a studfinder with a metal mode. You look for a vertical row (OK, column) of nails. If you have metal lath, they recommend punching tiny holes near the baseboard (so repairs will be inconspicuous) with a nail.
I have a really old nail finder that is essentially a compass. I think I bought it before Zircon or anyone else started making studfinders. Yes, I'm that old.
perfectbite
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Re: sensing wall studs through tile over plaster and lath.

Post by perfectbite »

RonH, Thank you.<p>"My father's sisters, with great tooth sucking sagacity, knowing nods and a smacking of the lips used to say: "Aye........ the old ways are the best ways."<p>And then they'd belch.<p>They knew opera and classical music though.<p>This wall has tile over it and that could add a very dense anywhere from 3/8" to 3/4" to the needle's remove from the nails. It's an 'In 1911 who knows what they did?' kind of deal. The area is directly across the Bay from the city of San Francisco and the earthquake of 1906, 5 years earlier may have caused them to run expanded metal in certain sections of the house. Who knows????? It was built almost a century ago and the technology they were using then was probably a score or more years old at the time they were using it.<p>Trying to sense a column of nails holds promise though. 'IF' I can get the 'clear' other side of the wall and measure back into the bathroom wall, that may work. <p>Otherwise, any SIMPLE schematics for a sensitive, magnetic amplified compass needle movement nail head detector would do.<p>BTW. Would increasing the amount of Voltage on a Hall effect sensor significantly extend its sensing range into a multi-layered non metallic solid?
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Chris Smith
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Re: sensing wall studs through tile over plaster and lath.

Post by Chris Smith »

They sell great little shower grab handles just for you. It has a mushrooming/toggling head much like a standard toggle bolt, only its about four inches across like a parachute when it expands and would be like ten standard toggles on each fitting.<p> You drill two holes in the wall about an inch in diameter and poke it through, and it disperses the weight across a very large surface area on both inserts. They cost more but they are strong and handi-cap legal to 400 pounds if I remember right?
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jollyrgr
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Re: sensing wall studs through tile over plaster and lath.

Post by jollyrgr »

I have an older version of the Zircon device. While it does a nice job it does lack certain performance compared to the newer models. Here is a listing of some of the newer devices:<p>http://www.zircon.com/SellPages/ScanAnd ... Studsensor<p>The new StudSensor Pro SL-AC has a deep scan mode and can detect AC wiring. This newer model goes up to 1-1/2" deep. It will also warn of AC wiring. (The original versions only go 3/4" deep.) This sensor has a Spot Light to show you the center of the stud. It shows up on the Zircon site for $28.95 and most likely sells in the store for much less.<p>The StudSensor Pro is a basic model but has the ability to scan 1-1/2" deep as well. A bit cheaper but without all the added features.<p>Basically the models break down as follows:<p>StudSensor (or similar name) for the basic model
PRO suffix means deeper scan (up to 1-1/2" deep)
SL suffix means Spot Light
AC suffix means it detects hot wires in addition to studs<p>I don't know how often you will use it but maybe it would be worth the $25 or $30 to get a newer model.<p>The Zircon stud finders work on capacitance. What you are suggesting, though, might be able to be done with sound waves. Instead of a mallet how about placing a piezo in a plastic tube and attaching a microphone to the outside. Thus you have a projected sound source forced through a tube and a close by receiver (the microphone) right next to the tube listening for the reflected sound waves. Connect the microphone to an amp with a meter on it. (A cassette deck with an analog meter maybe???) As you move the microphone/piezo tube across the wall you will note that at certain locations (aprox 1-1/2" wide) the sound level would change. You might also want to try a low frequency signal and use a larger speaker and some reduction fittings with PVC pipe.<p>Just some suggestions.
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perfectbite
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Re: sensing wall studs through tile over plaster and lath.

Post by perfectbite »

Chris, can you recall a name or where you came across the 'mushroom' toggle bolts? That would be very handy for future reference. <p>A clean, slightly irregular 1" hole in tile isn't impossible but I'd still have to know where the studs are for the 'mushroom' to clear them. <p>Jolly Roger, I bought the plain Zircon Pro sensor with the deep scan and it said that it won't work on plaster and lath, that's OK I thought, I'll be using it on stucco and e-mailed Zircon about using it on stucco. It won't work on stucco either because of the wire mesh and Zircon doesn't rent Superman with his X-Ray vision.<p>I'll experiment with the peizo 'thumper' (shades of Dune) and a mirophone connected to a VOM. Thanks for the idea.
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Chris Smith
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Re: sensing wall studs through tile over plaster and lath.

Post by Chris Smith »

I saw it on one of the TV shows, like this old house or something. It was a call in Q&A show. <p> I think you can ask one of the large chain suppliers of hardware for contractors about it because it was a highly approved "handi-cap" Item. <p>I would also imagine the web search for Handi-cap Items would be comprehensive?
perfectbite
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Re: sensing wall studs through tile over plaster and lath.

Post by perfectbite »

Chris, Web searches for me are like looking through a 6 million page yellow pages directory. Phrasing the right bloody question takes forever. Wading through the English speaking results takes another forever. It is good to know that they exist. I'll keep an eye out for them. Thanks.
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Re: sensing wall studs through tile over plaster and lath.

Post by Ed B. »

To "Perfectbite"
You mention -"The other side of the wall & measuring backwards."
I am assuming 'the other side' is NOT tiled ?
Take an electric drill with a 1/16th drill bit and 'on the other side of the wall' start some tiny pilot holes through the plaster (just above the bottom molding) until you feel the bit 'bite' into wood. Mark the edges of the studs by a few experimental holes near that spot. You may have to do this quite a few times because, heavens knows, how far apart the studs are. Once you have located the two extremes of each stud, mark the center. Then transfer these centers to the tile wall on the side. You can then drop a plumb line to these 'center marks' from the height that you wish to mount the handles and mark the tile wall there.
This should work. I would trust some long screws into a stud better than an expanding device that may pull out of lath, wire and plaster rather easily.
Then go back and patch the tiny holes with patching plaster and (hopefully) you will not have to paint over them.)
Good luck,
Ed B.
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Chris Smith
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Re: sensing wall studs through tile over plaster and lath.

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Mike
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Re: sensing wall studs through tile over plaster and lath.

Post by Mike »

how i'd find those studs is taking a sledgehammer to the wall and when it hits something besides the other side, thats the stud.<p>Simple, and non-technical.
perfectbite
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Re: sensing wall studs through tile over plaster and lath.

Post by perfectbite »

Thanks Chris. About 3/4s of the way down on this link's page is a 'Ringwood Newel post rail' which would be handy for healthy adults and children if you haven't seen it before. (It takes a while to load with a 56K modem and the exchange rate may be different.)
Teenagers swinging on it big time could wreck the bannister rail though.
http://www.westons.com/acatalog/Online_ ... s_910.html<p>Mike, Mike, Mike. (another bloody comedian) Given Jolly Roger's idea of a 'thumper' and a sensing microphone which do think would give the better response? Fixing them immediately adjacent to each other and moving both or fixing one and moving the other across the tile?
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Re: sensing wall studs through tile over plaster and lath.

Post by hamsterears »

Don't know if it would work on a wall that thick, but one method of finding studs is to use an electric razor. Turn the razor on, touch the casing to the wall, and listen to the sound it maks. When the razor is over the stud, the sound changes.
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Chris Smith
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Re: sensing wall studs through tile over plaster and lath.

Post by Chris Smith »

I think i read 800# load factor?
perfectbite
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Re: sensing wall studs through tile over plaster and lath.

Post by perfectbite »

Thanks Mike. That's a keeper idea. As it was the bathroom had been modernized and the studs were easily locatable by tapping. I had visions of an old cast iron claw foot bathtub and ye olde bathroom but it was very easy and the 82 y.o. lady was overjoyed. All jobs should have such customer satisfaction. (Her adult daughter wasn't too happy though. Her mother is quite feistily independent and could take it into her head to have a bath using the new grab rails and could fall heavily or get stuck when no-one else is at home.)
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