I’ve been renovating for decades, and I always have this tool in my collection

DIY newbies probably know that their tool kit should include a hammer and a screwdriver. But one tool that can be overlooked when building your indispensable home maintenance arsenal is at least one type of wrench. Yes, really! You may think this tool is only for professionals, but knowing how to use a wrench (and having an easy-to-use wrench) will save you some headaches. Trust me: I’ve been renovating and building for decades, so I know my stuff.

The primary function of a wrench is to tighten or loosen nuts and bolts, something you cannot do with any other tool. So, if you have any nuts and bolts in your home (and who doesn’t?), a wrench is an essential tool for any repairs or projects. But a wrench can only do its job if it’s able to securely grip whatever you’re trying to turn, so the first rule of how to use a wrench is: Choose the type of wrench that best suits your fastener.

First things first: not all wrenches are created equal. Fixed wrenches are designed to fit only specific sizes of nuts and bolts, while adjustable wrenches work with a variety of sizes. A hard wrench designed for the specific nut or bolt you’re trying to turn will grip it best, but you’ll need a lot of these wrenches to turn all the different nuts and bolts in your home.

You may instead prefer to have “one wrench to turn them all” – an adjustable wrench – in your toolkit. But no matter what you choose, you will need to know how to use it. Here’s a guide to how to use the most common types of wrenches.

Whether square or hexagonal, the heads of nuts and bolts have flat surfaces. The secret to using an open-end wrench effectively is to choose a wrench that fits tightly to these flat surfaces. If the fastener is not tight, the wrench will slip, and this may strip the lock head – making the job of loosening or tightening it more difficult.

If you know the head size in fractions of an inch or millimetres, it’s easy to choose the right wrench by simply noting the size marked on the handle. Otherwise, you have to look at it. When doing this, be sure to place the wrench on the flat surfaces of the mounting head. If it touches the edges where flat surfaces meet, it’s too big and will slide.

Here’s how to use an open ended wrench step by step.

Pro Tip: If a fastener is stuck so hard that the wrench starts to slip, stop immediately and lubricate the fastener with WD-40. If that doesn’t help, you need a wrench.

The wrench head forms a ring, and the inside of the ring is serrated to provide a better grip on the fastener head. The serrations and closed head help prevent the wrench from slipping while you are using it. For this reason, you can apply more torque than you can with an open-end wrench of the same size.

Pro Tip: Box wrenches usually have heads on either end of the handle, and they are slightly different sizes. If the head on one end doesn’t match your fastener, try the other end.

Here’s how to use a wrench step by step.

Pro Tip: In tight spaces, you can sometimes only move the handle a short distance before encountering an obstruction. In this case, there is no alternative to lifting the head off the fastener and repositioning the wrench. This gets tiring when you have to do it repeatedly, so if you prefer something easier, consider getting a box wrench.

You need a full set of box or open wrenches if you want to be ready for every nut and bolt you’re likely to encounter. An alternative is to have one or two adjustable wrenches (also called wrenches) on hand for emergencies and special circumstances.

The spanner has one fixed jaw and one movable jaw whose position you can adjust using the thumb screw. This allows him to grasp any size fastener that fits inside his jaws when they are fully extended. The disadvantages of this tool are that it is larger than a fixed-head wrench and that the jaws do not grip as tightly.

Here’s how to use an adjustable wrench, step by step.

An L-shaped Allen wrench is an odd type of wrench: Instead of gripping the sides of the fastener head, it fits inside a slot in the head, as a screwdriver does. Some people call it a hex wrench because it has a hex shape to fit into the hex hole in the fastener.

As with any wrench, the size of the allen wrench must match the size of the hole in the fastener. However, there are not many sizes, and since there is no such thing as an adjustable allen wrench, most people buy sets that include the most common sizes.

Here’s how to use an allen wrench step by step.

Pro Tip: Manufacturers prefer to use Allen nuts as a set screw for towel racks, faucet handles, and other common household items. Since bolts are so small and often close to a wall or other obstruction, it makes sense to insert the long end of the “L” into the nut and use the short end to turn it. This works because you don’t need a lot of leverage on the small nuts.