A2 or A4 stainless steel threaded rods: which to choose for outdoors
For tie rods and anchors outdoors, in damp environments or on facades, choose an A2 (AISI 304) stainless steel threaded rod. If you work near the sea or where chlorides are present, move up to A4 stainless, which is more corrosion-resistant. The 1-metre rod can be cut to size; diameters range from M6 to M30. Always use stainless nuts and washers: if you mix stainless and galvanised you risk corrosion between dissimilar metals.
The types
- Metre-length threaded rod. 1 m long, can be cut to size, in A2 or A4. For example the Fischer A2 stainless rod, the Fischer A4 rod and the Bossong A2 rod, 1 m long.
- Rod kits. Ready-made rods in a pack, such as the CSC Edilizia M12×250 kit.
- Threaded studs. Short pieces to be inserted in the hole with chemical anchor, such as the Fischer GS A4 threaded studs.
- Threaded adaptors. Used to go from one diameter to another, such as the Unifix M12 to M10 adaptor.
How to choose by job
| Job | What to get | Why |
|---|---|---|
| Facades, balconies, canopies in the open air | A2 stainless with stainless nut and washer | Withstands rain and damp without rusting. |
| Coastal areas, swimming pools, environments with chlorides | A4 stainless | A4 holds up better where A2 can stain or corrode. |
| Chemical anchoring outdoors | Stainless rod or stud suitable for the resin | Fixes in the hole without rust spoiling the grip. |
| Connecting two diameters | Threaded adaptor | Joins different rods without changing the whole system. |
The features to look at
- Type of stainless steel. A2 corresponds to AISI 304, A4 is the stainless steel for more aggressive environments. The type is stated in the name and in the data sheet.
- Diameter. In the collection from M6 to M30; the most commonly used are M8-M20.
- Length. 1 metre, can be cut; short pieces are also available, such as threaded studs.
- Standard. DIN 976-1 for threaded rods. This is the reference you will find in some data sheets.
- What is supplied. Some rods come complete with nut and washer. Check whether they are included.
- Pack. Some products come in packs of 50 pieces.
One thing to remember: the strength class of a stainless rod (for example A2-70) is shown on the data sheet and is not the same as that of a galvanised 8.8 rod. If the project requires a specific load, check the figure before substituting.
Common mistakes
- Galvanised nut on a stainless rod. Contact between dissimilar metals in a damp environment causes corrosion.
- A2 near the sea. Where chlorides are present A4 is the better choice.
- Not cleaning up the thread after cutting. Run a nut along it to deal with burrs.
- Thinking that stainless means stronger. Stainless steel resists corrosion, not necessarily load: compare the class.
Frequently asked questions
What is the difference between A2 and A4?
A2 (AISI 304) is the standard stainless steel for outdoors and damp. A4 contains molybdenum and is more resistant to chlorides and marine environments.
Can I cut a stainless rod with an angle grinder?
Yes, with a stainless steel cutting disc. Then clean up the thread and the edge, and run a nut along it.
Can I use a stainless rod for chemical anchoring?
Yes, if it is compatible with the anchor resin and with the hole diameters and depths specified by the manufacturer.
You will find the stainless rods and accessories in the A2 Stainless Steel Threaded Rods (AISI 304) collection; for advice or a quote, write to the AMES technicians.
More articles on this topic
Need this equipment?
The AMES catalogue lists more than 40,000 professional items, and if you are not sure where to start we will help you choose. Ask for a no-obligation quote or browse the rental fleet.