My understanding is that Greenguard needs to be covered by a thermal barrier like drywall when you install it. Is there a way to use a leftover piece of Greenguard to make an attic access insulation cover safely?

2 Answers 2


Sure can. The Green XPS foam board is very versatile, but it should never be used to walk on. However, it can work just fine in multiple layers as a ceiling access drop-in panel. Any other use for floor or wall access must be inserted into a frame that is structurally sound for the application.

  • do i need to add a thermal barrier to it if i use it that way? i don't intend on walking on it
    – nikolifish
    Nov 29, 2022 at 3:22
  • No, that would suffice as both your insulation and removable panel. You should still glue or tape 2 or 3 layers together for better insulation and durability.
    – Iggy
    Nov 30, 2022 at 0:38

Sure it can. Greenboard IS drywall, but it has a thicker paper shell that's coated with wax to make it water resistant. It's typically used in high-humidty locations such as bathrooms. However, it's not water-proof and shouldn't be used where direct exposure to water is expected (such as a shower stall).

  • 1
    I think OP was asking about green foam board insulation (XPS). I know he said Greenboard, but reading the rest of his question he's asking about insulating an attic access hatch.
    – SteveSh
    Nov 29, 2022 at 2:30
  • This is exactly what I was thinking as I started reading the question. I'll give it a +1. Heck, there is some amount of insulating property in greenboard/drywall, so maybe this is what the OP means...
    – FreeMan
    Nov 29, 2022 at 18:20
  • Yeah, I mean greenguard, not greenboard. Sorry for the confusion
    – nikolifish
    Nov 30, 2022 at 17:18
  • Title changed to remove "greenboard" Nov 30, 2022 at 17:21

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