by • October 2, 2015 • HVAC & Dehumidification, Insulation & Air SealingComments (5)4291

Best Attic Insulation (for the South)

This post is specifically for my friends in the Southern US.  No offense to the Northerners, but you Yankee’s generally have a full in-ground basement to run your HVAC systems and very few attics in the North have ductwork.  In the South we are mostly Slab-on-Grade concrete foundations or Crawl Space’s with Pier/Beam foundations.  That means our HVAC systems and most of the ductwork is running through the attic.  If this is your situation then watch my video to get the basics on a Conditioned Attic.  This non-vented attic makes a massive difference in the efficiency of a Southern home. 

-Matt Risinger

Risinger Homes in Austin, TX

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Risinger Homes is a custom builder and whole house remodeling contractor that specializes in Architect driven and fine craftsmanship work. We utilize an in-house carpentry staff and the latest building science research to build dramatically more efficient, healthy and durable homes.

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  • Addison John

    When installing roll roofing, do you use a starter strip as you would when installing a shingle roof? And what about the eaves. Are you suppose to apply the cement under the roll roofing near the eaves?

    Best James Hardie Siding Company Naperville IL

  • Andrew W. Lischuk

    Really enjoy your posts. Was hoping you might one day expand your information for those of us in the colder northeast as far as hvac and the like. Keep up the good work. You’ve got fans everywhere.

  • Ron

    I am starting on a new home in climate zone 3 (North Texas). We will be using Mueller Standing Seam or CF metal roofing with hidden fasteners.

    The attic will be part of the building envelope and will have 5/8″ plywood decking with 6″ of SES .5 open cell foam applied to the backside of this plywood with no other barriers installed over this foam. The SES open cell foam is rated as vapor impermeable at 3″ or more of applied thickness.

    The attic will have a supply and return from the heat pump that will also have a minimum 90 pint/day dehumidifier attached to the air handler supply and/or return plenums with a target humidity set point of 50%.

    The metal roofing can be applied directly to the plywood decking or be elevated on a batten and cross batten system that would allow vertical airflow and drainage. Mueller recommends Titanium underlayment with a perm rating of approx. .05 and I would also most likely add Grace Ice and Water Shield to the valleys, ridges and eaves.

    My questions:

    Is direct decking application of the metal roofing adequate to prevent condensation damage to either the decking or the backside of the metal roof or would the same setup on batten and cross battens to allow for better drainage and airflow be a better plan to prevent rust from forming on the metal roofing an to also allow external drying of the decking? Should a more vapor permeable underlayment such as GAF Deck Armor be used with either method to allow drying to the exterior?

    It appears to me that having the metal virtually floating in air would be better than having it heated from the directly coupled decking below and having a vapor permeable underlayment would allow the decking to dry in either direction.

  • Kristi Stogo

    Hi Matt! I saw your segment last weekend on spray foam insulation. Who would you recommend in Austin/Lakeway area?

    • Matt Risinger

      Sorry for my slow reply here! I’m behind in my comments. There are a ton of foam installers in our area. Whomever you choose be sure to check after their work closely before the truck leaves your site. Use a depth gauge to determine you got proper depth too. We are in a good area as there are lots of foam crews and prices are pretty low compared to many parts of the country. Best, Matt