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March 2026  ·  5 min read If you've been in the spray foam industry for any length of time, you've probably come across the term "Tier 4." It can feel like just another regulation to keep track of — but understanding why it exists and what it means for your business can actually make things a lot easier down the road. What is Tier 4? Tier 4 is the EPA's most advanced emissions standard for nonroad diesel engines, introduced progressively between 2008 and 2015. It requires sig