Diminishing returns on attic insulation
People want to know exactly how high they can stack attic insulation before it stops being effective. This uncertainty over diminishing returns complicates the project, leaving them unsure if they should use spray foam or if they need a vapor barrier under the ceiling drywall.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Finding the recommended minimum R-value for the climate and going slightly above itDid this help you?
- 2Focusing on air sealing gaps with spray foam and caulk rather than just piling on more insulationDid this help you?
- 3Hiring a professional to do the job instead of DIYDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I was wondering, if there is potential for building an addic. Should I consider putting in spray insulation?”source ↗
“And just leave the insulation as it is without a vapor barrier under the drywall on the ceilings?”source ↗
“I want to add insulation to my attic and I was wondering how high I can stack it? Are there diminishing returns?”source ↗
Where this came up
People with this problem also raised
- 4How much Teflon tape is actually too much?
- 6Is underlayment required under slate, tile, or thatch roofs?
- 2Buy once cry once or start with cheaper equipment?
- 3Is spray foam insulation bad for a roof deck?
- 2Can I add a switch or outlet to this electrical box?
- 4Do I need underlayment for luxury vinyl plank flooring?