What is a Stud Finder and How Do Stud Finders Work?

Understanding what each piece of construction equipment does, how it works and the nitty-gritty can be a daunting task to beginners and even the most experienced professionals.

In today’s article, we’ll be focusing on a tool every plumber, electrician or builder holds in high regard; the stud finder. If you struggle to figure out what stud finders are, the types of stud finders, and how they work, worry not, you’re at the right place. By the end of this article, you’ll be able to differentiate between the various types of stud finders, their defining features and what makes them tick.

If you are a seasoned professional or a budding DIY enthusiast, you’ll appreciate the accuracy this class of tools brings to the table. They essentially take out the “guesswork” from drilling tasks. This could save you a great deal of trouble if you’re working on surfaces with live electrical wiring hidden behind them.

But before we go into how stud finders work and all that good stuff, why don’t we learn the basics first? It’s good to cover them (sorry if you’re a professional and you know all this already, but remember you had to learn as well at some point). So this part is for the very beginners. So keep reading if you want to learn what a stud finder is and what a stud is.

What stud finders are?

A stud finder is a handheld device used to locate framing studs, nails, rebar, pipes, electrical wires and more behind walling surface. The tools detect the mentioned objects in drywall, wooden walls, plaster walls, and even concrete.

While there are many different designs of stud finders available, they can be classified into three main categories:

  1. Magnetic stud detectors
  2. Electronic stud finders
  3. Radio Frequency wall imagers

Stud detectors in each category offer unique specifications that meet the needs of a wide variety of projects. Whether DIY or professional, you can find a stud detector to match the specifics of your project at a reasonable price.

Most electronic and RF models are designed to detect the edges of studs and other materials detected at variable depths. A number of models come equipped with multiple scan modes with some being able to differentiate between different ferrous and non-ferrous materials.

What is a stud?

A stud is a vertical framing member which is a crucial part of a wall. Also known as wall studs, they are a fundamental component in frame construction and are typically made of timber. However, steel studs are also common and are particularly used in non-load-bearing walls and firewalls.

Studs can carry vertical structural loads, or may just be part of a wall where they are non-load-bearing. Wall studs are typically sandwiched between the top and bottom plates and are equally spaced.

The spacing is determined by the size and the spanning ability of the facing or cladding wall material.

Now let’s see what stud finders actually do and how they can be helpful for you as a DIYer or a builder.

How Stud Finder Works?

For a while, the only way to locate wall studs was to measure distances from a corner or using a hitting tool to bang on the wall and listen for differences in the acoustics.

Drilling holes in the wall to verify the wall stud positions was also a common albeit messy strategy.

Enter the modern stud finder and things got a whole lot easier. Stud finders work by measuring the difference in capacitance in the wall thereby determining positions where the wall is denser.

By measuring the electrostatic field of a wall, stud finders can detect slight differences in electrons flow. This allows stud finders to detect the changes in relative density and therefore highlighting the best possible locations to drill or drive nails. Some classes of stud finders make use of magnetic fields to detect nail heads, rebar and other metallic objects in wall studs.

These can also scan for electrical wires. The sensors on this type of stud finders work using an internal capacitor that detects dielectric currents.
Dielectric currents involve electric polarization where there are no free electrons moving around.

Instead of conducting the electricity, the electrons in different non-conducting wall materials separate into positive and negative. In places where there is a stud, this separation and the consequent flow of electrons is different and can be detectable using stud finders.

A stud finder measures the difference in the dielectric properties allowing you to know where there are wall cavities and where there are studs in the wall.

What stud finder is used for?

Stud finders are universal devices built to detect live electrical wires, wooden support beams, and metals in ceilings, concrete, gypsum walls and more. They detect and enable you to precisely pinpoint the location of wall studs, hydraulic water pipes, electrical wiring, reinforcement rods and more.

You can use a stud-finder to locate wooden battens/studs when drilling or installing frames, racks or picture mounts ensuring there aren’t any hidden pipes or live wires behind the wall you intend to work on.

Some Radio Frequency wall imagers can also be used to detect the presence of rodents and other annoying critters in your walls which potentially negates the need to take down entire sections of a wall just to get rid of them.

There are three types of stud finders: Magnetic, Electronic, Radio Frequency. Let’s find out a bit about each of them below.

Here are the 3 types of stud finders available on the market

1. Magnetic stud finders

Magnetic stud finders come in two variations, stationary and moving magnetic stud sensors. Stationary magnetic stud sensors operate via a small immovable magnet that detects screws and nails driven into studs to support the wall structures.

Using a stationary magnetic stud finder involves moving the magnet around the wall surface until you detect any hint of electromagnetism pulling the device toward the target location. Overall attraction significantly decreases where the metal objects lie deeper in the walls.

Studs located superficially in drywalls are easily picked up by a stationary magnetic stud detector.
Moving magnetic stud finders, on the other hand, utilizes a neodymium magnet that is suspended in a compartment in the device and is free to oscillate in response to detected metals.

The strength and intensity of exotic earth magnets such as Neodymium are well documented and its seamless movements allow the device to probe a wide array of construction materials. The attraction remains in a “home” position until it’s moved directly above a metal stud.

When scanning through walls with superficial studs, the neodymium magnet moves towards detected metal objects at a pace that makes a unique sound when it firmly latches onto the wall.

Given that a moving magnet negates the need for the user to be able to detect the magnetic attraction, you can use this type of stud finders to uncover studs buried deeper beneath plaster walls and tile.

In such instances where the studs are deeply-located, a softer pitch follows the slowed movement of the neodymium magnet.

2. Electronic Stud Finders

Materials such as wood are poor electrical conductors and are in fact ‘insulators’ meaning they do not conduct electricity at all.

They do however carry an ‘Electrostatic field’. This refers to a type of electrical/static field which can be picked up by an electronic stud finder using a ‘Capacitor plate’. Electronic stud finders detect any changes in the electrostatic field which correlates to the difference in density between plasterboard and a thicker and denser wood which is the stud.

Advances in electric circuit boards allow stud finders to detect with great accuracy the edges of the stud where the density suddenly changes.
Some advanced electronic stud finders can detect the type of material based on how dense it is.

This class of tools uses a combination of different scanning techniques with some of the stud finders being able to detect hidden metal pipes, electrical wires and screws/nails and more.

Some advanced models are capable of scanning up to 3 or 4 inches deep. This class of advanced electronic stud finder is referred to as ‘multi scanners’ or multi-purpose stud finders. They are useful in more than just finding studs in drywalls and plaster walls.

They can be used to find the beams in the ceiling, floor, and metal objects behind walls or other surfaces. These use a combination of small-scale radar or RF technology, metal detecting hardware, density sensors, and magnets.

A combination of all these scanning methods allows advanced models to give an accurate depiction of what’s embedded within a wall.

3. Radio frequency (RF) or Small-Scale Radar stud finders

A newer version of stud finders uses low-power radio frequency technology to detect objects enclosed within a wall cavity. RF stud finders are imaging devices that pair with smartphones which then show a picture of exactly what lies behind a wall.

These devices can accurately identify materials such as wood, PVC, electrical wiring and even small rodents and insects through concrete and wallboard.

Radio Frequency waves easily penetrate most common building materials and with a suitable detector, you can pretty much “see” what lies behind a wall, its exact dimensions, and depth. That’s why this type of stud detector is considered to be the most accurate stud finder from the three.

The current generation of RF wall imagers is designed for use with Android phones with plans to roll out compatible software on other platforms soon. The RF scanning device is the same size and weight as your run of the mill mobile phone products.

The scanner comes with a micro USB cable to link the device and a smartphone, and an accompanying app.

Do I need a stud finder? How to find a stud without a stud finder?

The question of whether or not you need a stud finder is entirely dependent on the nature of the tasks at hand.

For professional construction or remodeling projects, you would absolutely need to have a stud finder.

DIY tasks that involve drilling or driving nails/screws through risk-prone areas might require you to have a stud finder as well to avoid drilling through live electrical wiring.

When you absolutely need to know the precise location of wall studs, pipes, wiring, and the exact dimensions/boundaries, then stud finders are a necessity.
However, in small scale DIY projects, you do not need to get the latest and greatest professional stud finder just to mount a picture frame.

A simple yet effective method would be using common refrigerator magnets to detect nails and screws around the area you are working on.

Here’s how to find a stud in a wall if you don’t have a stud finder

When all you want is to hang a picture, mount a shelf or simply set up a TV mount, you may not necessarily have to own a stud finder. There are a couple of methods you can use to locate studs without using specialist equipment.

Step 1

The old refrigerator magnet method: Most screws and nails commonly used in home construction are ferrous meaning they are magnetic. Chances that there are nails or screws within your studs are quite high and therefore a cheap magnet will do just fine.

Simply move the magnet along the wall until you feel the magnet gets drawn in. Mark where the attraction is strongest. Now you have a rough idea of where the stud is, and where you shouldn’t drill or hammer directly.

Step 2

Use switches or wall-mounted power outlets: The idea here is knowing that either of those switches or power outlets are mounted on a stud or on two wall studs on each side. Using suitable intervals, you can space where you want to hammer or drive screws.

Step 3

Knocking on the wall: The method is fairly simple and should give you a general idea of where studs lie and the direction of travel. Using a tool such as a hammer, gently knock around the general area you intend to work on while taking notice of the acoustics.

When you finally hit a denser material underneath, the sound will change indicating the presence of a stud underneath. Mark this position and continue along a set direction whilst marking any changes in the acoustics.

Step4

Know your wall construction: Depending on how old your house is, the construction follows a set standard with regards to how wall studs are spaced, their dimensions and so on.

If you know the floor plans to your house, you can easily approximate where wall studs are by measuring from a point of reference. While not the most accurate method, it can give you a general idea of where wall studs are or should be.

As you can see, a stud finder is a great little tool to have in your toolbox when doing little jobs that require you to drill your walls.

In some situations, as we’ve seen above, you might not need a stud finder, just follow the steps mentioned in the little step by step guide and you’ll be fine most of the times.

I hope we’ve covered this topic very well and you know now more about stud finder than what you knew before coming to ninjaDIY. If you have questions just drop them below and I’ll answer as soon as I can to the best of my knowledge.

Hello everyone. I’m Adrian, I’ve been working in the construction industry for the last 5 years or so … doing all sort of jobs from handyman to crane operating and everything in between :) I am a blogger as well at ninjaDIY.com … where I talk about anything related to construction, building, power tools, DIY home improvement and much more.

Your comments are welcome!

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