Railroad ties are most commonly treated with creosote , a wood preservative that helps resist decay, insects, and moisture. Some ties are also treated with creosote-borate or, in smaller amounts, copper naphthenate -based preservatives; a few modern ties may use other systems or be made from naturally durable wood species.

Quick Scoop

  • Most common treatment: creosote.
  • Other treatments: creosote-borate and copper naphthenate / copper naphthenate-borate.
  • Why it’s used: to protect the wood from rot and extend service life.

One caution

Creosote-treated ties can contain chemicals that make them unsuitable for many home landscaping uses, especially in gardens or places with frequent skin contact.

If you want, I can also tell you how to identify creosote-treated ties or whether old railroad ties are safe to use in a yard.