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How To: Find Studs in a Plaster Wall

how to find studs in a plaster wallIf you own an old house with plaster and lath walls, you may have discovered how utterly useless a stud finder can be. Most smaller items can be hung pretty securely anywhere on the wall by screwing into the wood lath, but for heavy things that weight more than 10-15 lbs, like large mirrors and TVs, you’ll need to learn how to find studs in a plaster wall.

Don’t waste your money on that stud finder. Try these simple and time tested tricks to find studs in a plaster wall the next time you need to hang something in your old house. The third trick is my personal favorite because it never fails!

#1 Find an Electrical Box

Electrical boxes for outlets and light switches are supposed to be attached to studs. Though there may be an occasional free floating box in an old home, you have an excellent chance of finding a stud on one side of the box. To see which side the stud is on, take the switch plate cover off and take a peak inside. Either turn the breaker off, or be careful not to touch any wires before attempting this or you can get a nasty shock.

Once you find the stud, you can measure off 16″ to find the next one most times. Most houses built in the last 100 years were framed 16″ O.C. (on center) and some were framed 24″ O.C. although many old houses may have unusual stud spacing so this method may not work for everyone.

#2 Knock on the Wall

This one may seem old fashioned, but gently knocking your hand along the wall and listening for differences is a pretty accurate technique to find studs. When you knock on wall sections without a stud, you will hear more resonance from the hollow space behind. Once your knuckle hits the spots where a stud is located, the sound will change to more of a dull thud. Move along the wall and look for a pattern to show itself, and you’ll slowly be able to see your stud spacing.

#3 Use a Magnet

How to find studs in plaster wall
The magnet trick!

This is my favorite method and the reason is simple. It works every time! Grab the strongest magnet you have and tie a piece of dental floss or string around it. Dangle the magnet against the wall and slowly move it horizontally across the wall. You have to go slow. Every so often, the magnet will stick to the wall a bit on the stud location. It has to be a strong magnet for this to work, so those floppy pizza magnets won’t cut it.

The reason this works is because the wood lath is nailed to the studs, and the magnet is attracted to those nails. Keep in mind there are some spaces between lath vertically so if you’re not having much luck try moving the magnet up or down a bit so that it is over top one of the hidden nails.

Update: Since I first wrote this post we have begun offering a totally cool new product called StudPop which takes the magnet trick to the next level. This simple stud finder is a powerful magnet that pops into place when a stud fastener is detected. Just like my magnet trick, but a bit more refined than tying dental floss around a magnet. Check it out here!

#4 Use a Metal Detector

If you happen to have a small metal detector, you can use this along the same premise as the magnet technique. Beware that depending on the sensitivity of your metal detector you may pick up old wiring, cast iron plumbing, or other things hiding in the wall. Unlike the magnets which aren’t strong enough to be attracted to a pipe that is a couple inches recessed into the wall the metal detector may give you false readings.

So, there you have it. No more fumbling with expensive stud finders that give you all kinds of weird readings. Other than the metal detector, these techniques have been used for decades to find studs in plaster walls. The best part? They cost you almost nothing. And saving money is an important thing with all the other repairs lingering in an old house.

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65 thoughts on “How To: Find Studs in a Plaster Wall

  1. 1850s house, lathe. Trying to hang a large shelf. Magnet on string finds but 4 nails on entire wall; two about 5′ off floor 21″ apart and another two about 4′ off floor about 21″ apart. If they are nailed into the same stud it is a 4″x 4″x 10′, or they are somehow anchored to the sides of the studs. Nothing else found on the whole wall, I think all the wiring was added by running wires down inside the walls into the basement. The outlets are screwed into the baseboard and switches are just screwed into holes cut in the lathe. Seem to be no nails at all in the baseboard, at least ferrous ones. Standard stud finder tells me the whole wall is a stud and hot with wiring. I assume there are old gas lines in there too as I had to unscrew some to put in ceiling fans. Seems like there should be nails in each lathe along the entire stud, not just 4 of them holding all the lathe and I never heard of 21″ on studs and there should be more than 2 studs on a 14′ long wall. Any thoughts?

  2. Zircon’s i360 studfinder has a METAL detector setting along with STUD and DEEP SCAN. Sliding the unit back and forth (going about a couple inches up or down with each pass) quickly started showing the locations of the support stud nailed points were. A couple of refining sweeps helped find the stud boarders, while sweeping vetically up & down confirmed more nailed locations along the stud.

  3. Stanley magnetic stud finder! It just has a little peg on a pivot. When you cross over a nail it stands straight out. Super simple and works great. Plus… like 2 bucks

  4. I tried the magnet trick on my walls, but it stuck everywhere. Someone else said they have expanded metal mesh, and they had a similar result. Do you think that’s what is happening with my walls as well? If so, do you have any suggestions?


  5. Thank You. We just bought an old house and I’m putting a second handrail in the stairway. I missed the stud with the electronic sensor. I have just the magnet!

    1. So glad our post was helpful for you! Good luck with your old house restoration and thank you for commenting on our post! We’d love to be kept in the loop on your projects. Feel free to write us any time!

      -Alyssa (Designer at The Craftsman Blog)

  6. Bought a stud finder, only to find out inside the package that it will not work on plaster walls! Checked out the outlet box, only to find out that it was cut directly into the lath and screwed on the top and bottom of the electric box! (who does that!!!!????). Knocking on my wall just hurt my tiny little knuckles! So, I am going to try the magnet thing now! If I don’t have a powerful enough magnet . . . I will be purchasing a STUD POP!!! I love all these helpful comments and am grateful for Scott and his wisdom! 1900 home means “The Craftsman Blog with Scott Sidler” is my new best friend!

    1. Hi Andrea,

      Did the magnet trick end up working for you? If not, I hope you were able to order a Stud Pop and I hope it changed your life! (Not to be dramatic, but really haha)

      Be sure to subscribe to the blog (and our YouTube channel! ) to get the latest articles directly to your inbox. You’re going to be needing that with your lovely 1900 home!

      Thanks so much for your encouraging comment on the blog. The world needs more of that!

      I hope you’re having a wonderful week and I hope your DIY projects are going amazingly!
      -Alyssa at The Craftsman Blog

  7. This is absolutely genius! I’ve lived in my house since 2002 and have always struggled to find the studs. I used a small magnet that’s used for a bike computer hung from some dental floss, and it adhered to the wall perfectly on the studs!

  8. The most powerful magnet I own turns out to be the magnetic “key” to a child-safety cabinet lock — it can lift about 6 or 7 pounds. I’ve been able to find studs by sweeping it around directly by hand.

    The current challenge is a wall where this isn’t working. Knocking isn’t working (wall sounds progressively more hollow as I sweep left.) No electrical boxes. So: Dangle the very powerful magnet on a string.

    …I can’t get it to face the wall. It’s acting as a compass, dangling from that string, and the wall is not North! D-:

    (I did eventually get it to work! The trick is to tape a stiff piece of paper to it to act as a surface guide and prevent it from rotating.)

    1. Oh jeez. Amazon sells rare earth magnets for $10 – they’re incredibly powerful, they can hold 120lbs and will easily find the nails in your studs behind the wall.

    2. I’ve tried the Hanson to absolutely no avail… same dangling problem.

      Could you clarify WHERE you take a stiff piece of paper? On the magnet/finder itself?


  9. Those C. H. Hanson stud finders should come with large stickers across the front: “FOR USE ONLY WITH DENTAL FLOSS.” Handheld it didn’t work for me at all; with dental floss it worked great. Thanks for the tip!

  10. Hmmmm …… just clad a new shippiong container home with plaster board. Wish this could work but the shipping container is metal. LOVE the location of the electrical boxes, though 🙂

  11. I wish the magnet method worked for us, but we have expanded metal mesh between the lath and the plaster! So magnets stick to the entire wall. No good.

  12. The magnet method is the best in my experience. I used it after reading this post in 2014. Now there is a commercial one available from C.H. Hanson (
    This technique works in Sweden too, but the studs are spaced differently there, and the panelling is much thicker because of the cold weather there.
    The magnet method will work well as long as builders don’t use rustproof stainless steel nails!

  13. Ack!!!! You’re the bomb! Worked perfectly. Thrilled. Can’t wait to tell everyone in my neighborhood of old houses. 🙂

  14. If you just heard an explosion, it was the sound of my mind being blown. I moved into our family homestead farmhouse built in 1863 about 5 years ago, and I had basically given up on easy ways to locate studs. I tried the magnet trick using my magnetic billfold and a piece of string, and it worked…even through aweful wood paneling over the old plaster. Thank you so much. Every project in this house turns into a chase down a rabbit hole, so something this simple that actually works is a breath of fresh air.

    1. Same exact feeling. My house was built in 1907 and for some reason I never thought to use magnets. My life just got A LOT easier.

    2. I’m amazed! I’ve been decorating my house which was built in the early 40’s and has plaster walls. I’ve never been able to find a stud till now. I built a farmhouse buffet table and wanted to put use a 3’ x 32’ slab of wood for a shelf. I was worried I’d never find a stud. Thank you! Decorating just got easier!

  15. Worked great for me with a magnet from a computer hard drive. Only worked when I tied a string to it, though. Held it by hand and tried running it along the wall, but couldn’t sense the magnet grabbing. But with a string tied to it, immediately i could see the pull as it passed over a nail. Thank you!

    1. I found that a medium strength magnet too worked well but not with with a string. But moving it by hand slowly across in X and Y axis, I could locate the studs. May be the string method did not work because the magnet i used was not very strong and the studs could not grab the magnet. This method worked well in Sweden too, where the wood panelling used is thicker, and they don’t follow 16inch spacing of supports.

    2. I skipped the string step, and didn’t realize how important it was. Shortly after attaching the magnet to the string, I found that the pull was indeed very gentle, but the string made it happen!

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