See through walls

Looking for a support stud behind your wall linings can be one of the most frustrating tasks you carry out and usually it’s only for a small project. Hanging a picture, putting up a set of shelves or installing a television mounting bracket all require you to be exactly sure of where the studs are located in your walls.
 
Thankfully, there are a myriad of stud finders and wall scanners available on the market. Depending on what task you are carrying out, there is a model that will suit your needs. How To magazine looked at what you should consider when choosing your stud finder at Mitre 10.
 
Usage
 
Take into consideration how often you will use a stud finder, as this will dictate how much you need to invest in a unit. For the casual DIY enthusiast, it’s likely that you will use a stud finder to merely indicate where the edges of a stud are and that’s about it. This warrants you to spend your money on an entry-level model that will give you just that information, nothing more and nothing less.
 
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Perhaps you need a stud finder that has a bit more range and has the ability to scan through tiled bathroom walls or thicker walls. How about a stud finder that can tell you where live wires are and scan for metal pipes or ducting? This is a step up in investment, but well worth the money. Look for products like DeepScan and especially products featuring a wire warning detection accurate up to 5cm deep.
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How they work
 
The science behind these tools is surprisingly simple. The tool measures the absorption of electrical charges in the scanned surface (capacitance) and measures it in ‘farads’; the greater the density, the greater the capacitance.
 
When you hold a stud finder against the wall, it emits a weak electrical field. Sensors inside the unit then detect how much time it takes for the wall material to reach a certain voltage. As the unit moves closer to a stud, the capacitance increases and alerts you that the density of the wall is such that there has to be a stud in that location.
 
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Stud finders are divided into two classes and each performs a different function:
 
Edge finders
 
The device scans the wall as you move it across the surface. When it detects a change in the density of the wall, it will emit a tone and you know you have found one edge of the stud. Perform the task in the opposite direction to find the other edge of the stud and from there you will be able to work out where the centre of the stud is.
 
Centre finders
 
As the name suggests, these units are ideal for finding the absolute centre of the stud on the first pass. Using the same technology as any other stud finder, these units illuminate the stud centre and make it easy for you to ensure your project has the best support.
 
Stud finder model photos
 
Ceilings
Many ceilings have irregular, textured surfaces that interfere with your stud finder's ability to work properly. Dragging the tool across a textured ceiling will likely damage the surface, so an easy solution is to scan through a thin sheet of cardboard, such as a manila folder. This creates a smooth, flat scanning area, while keeping your ceiling pristine.
A few different variables lead to irregular ceiling density, the most common being uneven insulation. The foil that covers some types of insulation will also cause your device to fail. Ceiling patches are an additional concern, as density differences can be mistakenly identified as studs.
A high specification multi scanner will look for metal and isolate nails used for attaching ceiling board to the studs or joists. It’s always good to allow plenty of time to map out a wide area of ceiling, so that you can differentiate stud nail patterns from pipes and ducts.
 
Floors
Stud finders can also locate joists in your floor, as long as your flooring does not have several layers of material with different levels of density, or materials that are denser than the wood joists you're trying to find.
Materials that interfere with a stud finder's ability to find floor joists include carpet and padding and various types of hardwood flooring. In addition, scanning through tile can produce the same irregular results. It is in these situations that you need a unit with a metal scanning mode to locate the nail heads to identify the floor joists.
 
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Stud finder projects:

• Hang pictures, mirrors and shelves.
• Hang hooks.
• Inspect and demolish walls.
• Install trim.
• Tighten floor joists.
• Install ceiling fans.
• Install recessed lighting.
• Mount wall brackets.
• Install electrical outlets.
• Run cable and wire through wall.
• Install grab bars.
• Install cabinetry.
• Install surround sound speakers.
• Install flat screen televisions.
• Anchor heavy furniture.