0 Helpful?

I have a 1-story dwelling with an attic (cold space) that has approx. R-30 insulation

I have a 1-story dwelling with an attic (cold space) that has approx. R-30 insulation but NO plastic vapor barrier between the sheetrock and the insulation....

I am considering adding a radiant foil barrier on top of the the blown insulation.
What are potential problems could I have, as a result of this installation? Moisture problems? Our home is in Northfield, MN 55057

Asked by gary schutte
Posted Aug 27, 2014 12:52 PM ET
Edited Aug 27, 2014 2:31 PM ET

Tags:

3 Answers

Select your preferred way to display the comments and click "Save settings" to activate your changes.
1.

Don't do it.

Foil is a true vapor barrier, less than 0.05 perms, and if located on the cold side of the assembly even vapor diffusion is enough to create wet/frozen insulation in your climate at the top layers if you trap it.

The thermal benefit of a foil radiant barrier is truly miniscule in a MN climate too- you're far better off spending the money on air sealing & insulation.

Answered by Dana Dorsett
Posted Aug 27, 2014 1:11 PM ET

2.

Gary,
Dana is right on both points.

A radiant barrier on top of your attic insulation will make the top layer of insulation damp.

You'll get much more of a performance improvement by spending the same amount of money on deeper insulation. (Of course, if you haven't sealed the leaks in your ceiling yet, that work always comes first.)

Answered by Martin Holladay, GBA Advisor
Posted Aug 27, 2014 2:26 PM ET

3.

Gary,
For more information on air sealing, see Air Sealing an Attic.

For more information on radiant barriers, see Radiant Barriers: A Solution in Search of a Problem.

Answered by Martin Holladay, GBA Advisor
Posted Aug 27, 2014 2:51 PM ET

Other Questions in General questions

Fill stud cavity with fiberglass insulation?

In Green building techniques | Asked by Joel Cheely | Dec 4, 16

How to employ a mixing valve in a closed loop radiant heat system

In Energy efficiency and durability | Asked by Roger Smith | Dec 1, 16

How important is a thermal break between a house foundation and an attached garage foundation?

In Green building techniques | Asked by Eric Whetzel | Dec 2, 16

How would you air seal existing sheet rock to the bottom plate?

In Energy efficiency and durability | Asked by david schreiber | Dec 3, 16
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!