Tools made easy: How to use a stud finder

A stud finder is designed to locate the timber studs hidden behind plasterboard walls. Think of studs as the wall's skeleton – they're the vertical pieces of timber that support the plasterboard and give the wall its strength.

Because screws fixed into a stud have solid timber to grip, they're able to support much heavier loads than plasterboard alone. By finding the stud before drilling, it's much easier to create a strong, secure fixing that will stand up to everyday use for wall mounting.

A stud finder is most useful whenever a project involves hanging something with a bit of weight. Floating shelves are a great example, as they'll often be supporting books, plants or decorative items. It's also handy for mounting television wall mounts, large mirrors, coat hooks and wall cabinets.

While lighter items can often be installed using plasterboard anchors, heavier items should be fixed into a stud wherever possible. Otherwise, there's a risk the fixing could loosen or pull out of the plasterboard over time.

Start by marking where your item, for example floating shelves, will be positioned using a tape measure and spirit level. 

Place the stud finder flat against the wall and switch it on. Follow the manufacturer's instructions for your stud finder, then slowly slide it across the wall until it lights up or beeps to indicate a stud has been detected. 

Many modern stud finders use lights, arrows or a centre marker to show when the middle of the stud has been found. If the stud finder doesn't indicate the centre automatically, scan from both directions and mark each edge before finding the midpoint with a pencil.

Before drilling, double-check the stud location and check for electrical wiring and plumbing using the stud finder's detection modes if available, or another suitable detector.

As an extra check of the stud position, gently tap the wall with your knuckle. The sound will usually be more solid over a stud and more hollow between studs.

Once you've checked for hidden services and everything lines up, drill a small pilot hole to confirm the fixing is centred in the stud before installing the shelf bracket or screw. Taking a few extra minutes to check the position can help avoid unnecessary holes and ensure the shelf has a strong, secure fixing point.

Wear safety glasses and ear protection while drilling and use screws and fixings that are suitable for both the wall type and the item being installed.

Once the stud has been confirmed, install the floating shelf according to the manufacturer's instructions.

Once you've located the studs and checked the wall before drilling, you're ready to plan your fixing points and install your shelf or other wall-mounted item according to its manufacturer's instructions. 

How do I know when my stud finder has found a stud?

Follow the indications provided by your particular stud finder. Many models use lights, arrows or a centre marker to indicate a stud and, on models with that feature, its centre.
If the tool doesn't identify the centre automatically, scan from both directions and mark each edge before finding the midpoint.

Should I check for wiring or plumbing before drilling into a stud?

Yes. Before drilling into any wall, check for electrical wiring and plumbing using your stud finder's detection modes if available, or another suitable detector.
Do this before drilling a pilot hole, even when the stud finder indicates that you've located a stud.

Can I find a stud by tapping on the wall?

Tapping can be useful as an extra check because the wall will usually sound more solid over a stud and more hollow between studs. Use it as a supporting check rather than replacing the stud finder.

Do I need a stud for floating shelves?

For the heavier wall mounting projects covered by this guide, fixing into a suitable stud where possible gives the screw solid timber to grip. Follow the shelf manufacturer's installation instructions and use screws and fixings suited to both the wall type and the item being installed.

What if my stud finder doesn't show the centre of the stud?

Scan across the area from both directions and mark each edge of the detected stud. You can then find and mark the midpoint between those edges before drilling.