Helpful? 0

Insulating a split level attic

I have an attic above my kitchen with 3 interior walls and I am trying to figure out how to insulate it correctly.

Currently the walls facing the bedroom and the entry way have fiberglass insulation.
The floor has cellulose insulation. ~2-3 inches.
The ceiling rafters has ~4" of white fiberglass/denim insulation inside of perforated plastic bags between the ceiling rafters, this appears to be pretty consistent, but I suspect it is leaking a bunch of air.

The roof line is several inches about the existing insulation and connects to the space above living rooms vaulted ceiling.

I am thinking about putting rigid insulation boards below the ceiling to air seal the space, is this a good idea or would it cause problems?

Asked by John Reuter
Posted Wed, 08/20/2014 - 13:47
Edited Wed, 08/20/2014 - 14:12

Tags:

1 Answer

Select your preferred way to display the comments and click "Save settings" to activate your changes.
1.
Helpful? 0

John,
It's hard to visualize the walls and ceilings that you are describing, but a few principles apply.

If you plan to use fiberglass batts, make sure that the batts are enclosed on all six sides by an air barrier. Rigid foam can be used as an air barrier. Check with your local building inspector to find out whether you need to protect the rigid foam with gypsum drywall, or else use Thermax foam (which doesn't need the drywall).

Here are links to two relevant articles:

Installing Fiberglass Right

Two Ways to Insulate Attic Kneewalls

Answered by Martin Holladay, GBA Advisor
Posted Wed, 08/20/2014 - 14:10

Other Questions in General questions

Sensors in House Envelope

In Energy efficiency and durability | Asked by Karl Overn | Dec 21, 14

Polyiso for basement

In Green building techniques | Asked by sr kod | Dec 20, 14

Wet OSB - how much water can it take?

In General questions | Asked by colleen1 runyen | Dec 17, 14

Ventilating

In Mechanicals | Asked by Vishy S | Dec 21, 14

Modern (hydronic) heating and what all should start to know as of 2014

In Mechanicals | Asked by aj builder, Upstate NY Zone 6a | Dec 4, 14
Register for a free account and join the conversation


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