How To Achieve R 49 In Attic

Fill available space with roxul comfortbatts.

How to achieve r 49 in attic. 2 r 23 batts will just fit inside a 2x12 rafter for r 46. It also suggests r values when adding insulation to uninsulated or under insulated attics crawl spaces and walls. Then install a sheet membrane for air tightness. For example energy star recommends r 30 for a roof in the southern united states r 38 for the middle of the country and r 49 for the northern part of the country.

You can achieve better thermal performance in your attic by adding an additional layer of insulation. Click the button to calculate the approximate r value for this job. Spray foam insulation r values. For your attic project install r 49 ecotouch insulation.

References department of energy. Obviously if you don t have 17 inches of attic space then you ll have to use some other kind of insulation. Input depth of existing blown in insulation in inches. The table opposite suggests r values by zone as indicated in the map of the united states.

As dana mentioned use a smart vapor retarder. Achieving greater r values in exterior walls in exterior walls add insulating sheathing to achieve a greater r value in your wall system. Amongst all of the popular types of insulation currently used by the industy spray foam insulation features the highest r value per inch. Evaluate your house s current r value and recommend whether additional r value is needed and appropriate types of insulation.

If you truly need r 49 that won t work but if that is just a target r 46 is close. This calculator is to be used as an estimating tool only. Offers exceptional thermal and sound control performance. It s been a while since i dealt with insulation but i m pretty sure your gc was talking about the standard fiberglass batting the pink stuff when he said that you would need 17 inches of insulation to reach your required r value of 49.