Cor-Ten Steel. What’s the Difference?
Designer: Chris Gustard
We get a lot of questions about Cor-Ten Steel (a/k/a weathering steel plate or high-strength corrosion resistant plate), mostly from our landscape designers and contractor clients, on how to use it, what’s the difference between this and raw steel. If you’re not familiar, here’s what makes this material special:
- It has a beautiful and natural rust finish which has a refined rustic look.
- It starts out looking like raw steel, but once cleaned of all oils, will quickly (within one month) take on a rust finish.
- The surface is ‘reactive’, so the rust finish is variable and changing.
- It’s core is non-corrosive, therefore it will withstand the elements without degrading like raw steel.
- It’s available as a sheet material in thicknesses of 3/16″ to 5″.
In general, we have used Cor-Ten for planters, gates, railings, walls/retaining walls, and planting bed edging.
FAQs
- Will it ‘drip’ rust and stain? Yes.
- Can I use it as a fountain? We haven’t. A lot of designers like this look for water features, and we’ve seen it used for fountains, but beware. Your water will most likely be brown and cloudy, and this can cause problems for your pumps.
- Is it more expensive? Yes, but worth it if you want it to last forever.
- If used for a planter, won’t the roots get too hot? Maybe. We’ve used bubble wrap or other filter fabrics to line our planters.
It’s one of our favorite materials. Please share your stories with Cor-Ten.
Advertisement
I have designed planter boxes with cor-ten, howver, client and contractor chose to use cold-rolled steel which is cheaper, supposedly as durable, and has the same naturally rusted look that we were after. On that project, it was even used for the fountain which was treated with a product (i believe it was Zero-Rust) inside the fountain trough and then with a coat of brown paint. It is a good-looking fountain, and we haven’t had any problems with the re-circulating water.
In another project, cor-ten was used for a fountain, and the rusting has been continuous for several months which makes the water murky. The contractor is looking for a pump that can handle the particles. Of course, it is possible to coat the fountain with special paints (see marine trade) – however, this would eliminate the naturally rusted look that is so desirable.
Thanks for the tip regarding the interior insulation of the planter boxes. I believe this wasn’t done in my before mentioned project but all has worked so far (installation last summer).
Here a correction of my earlier post: I was mistaken about the steel used in the pond element; it was hot rolled steel. And installer and client are at this point investigating how to prep the fountain trough inside: the water is now turning milky, and the treatment with ZeroRust is suspected to not be working out. To be continued…