Threaded rod — also known as all-thread, threaded bar, or studding — is one of the most versatile fastening products available. A single 1 metre length can be used in dozens of different applications, and the range of sizes, grades, and finishes means there's a threaded rod for almost every situation.
In this guide we cover everything you need to know about metric threaded rod: what it is, how to use it, which size and grade to choose, and what accessories you'll need.
What is threaded rod?
Threaded rod is a long, straight metal rod that is threaded along its entire length with a metric coarse thread. Unlike a bolt, which has a plain shank and a head, threaded rod has no head and is threaded all the way from one end to the other. This means you can cut it to any length and fasten it at any point along the rod using standard hex nuts and washers.
Threaded rod is manufactured to DIN 976 and is compatible with any standard metric hex nut of the same thread size and pitch.
Common sizes and when to use them
| Size | Thread pitch | Common uses |
|---|---|---|
| M6 | 1.0mm | Light fixings, electrical conduit supports, cabinet assembly |
| M8 | 1.25mm | General construction, suspended ceilings, HVAC supports |
| M10 | 1.5mm | Structural fixings, screed tripod assemblies, pipe hangers |
| M12 | 1.75mm | Heavy structural work, machinery mounting, anchor bolts |
| M16 | 2.0mm | Heavy civil engineering, bridge and highway work |
| M20–M24 | 2.5mm | Very heavy structural applications, foundation bolting |
Grade 4.8 vs Grade 8.8 — which do you need?
Threaded rod is available in two common strength grades:
- Grade 4.8 — standard mild steel. Suitable for the vast majority of construction, fabrication, and general fastening applications. The 4.8 designation means a tensile strength of 400 N/mm² and a yield strength of 320 N/mm².
- Grade 8.8 — high tensile steel. Used where greater strength is required — typically structural steelwork, heavy machinery, and high-load applications. Tensile strength of 800 N/mm², yield strength of 640 N/mm².
For most domestic and light commercial construction, Grade 4.8 is perfectly adequate. Choose Grade 8.8 when you're working to a structural specification that requires it, or when the joint is subject to very high loads or vibration.
How to cut threaded rod to length
Standard threaded rod comes in 1 metre lengths, but you can easily cut it to any length you need:
- Mark the cut point with a marker or wrap masking tape around the rod at the required length.
- Use an angle grinder, hacksaw, or cold saw to cut the rod. An angle grinder with a cutting disc gives the cleanest cut.
- After cutting, the thread at the cut end will likely be slightly damaged or burred. Run a nut down past the cut and back off — this will clean up the thread and allow a clean nut engagement.
- Alternatively, use a die of the correct size to re-cut the thread at the end.
If you need short lengths and don't want to cut full rods, we also stock pre-cut threaded studs from 40mm up to 500mm.
Accessories for threaded rod
To use threaded rod effectively you'll typically need:
- Hex nuts — one or two per fixing point. Always use the same finish as the rod (BZP with BZP, HDG with HDG).
- Washers — flat washers under each nut to distribute load and protect the surface. Use square plate washers for timber or masonry applications.
- Spring washers — for applications subject to vibration, add a spring washer under the nut to prevent loosening.
- Threaded rod connectors — to join two lengths of rod end-to-end, use a coupler nut (also called a connector or extension nut).
- Plastic end caps — snap over the exposed end of the rod to protect the thread and cover any sharp edges.
