How To Achieve R 49 In Attic

Click the button to calculate the approximate r value for this job.

How to achieve r 49 in attic.

As dana mentioned use a smart vapor retarder. Offers exceptional thermal and sound control performance. 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.

Then install a sheet membrane for air tightness. Bag meets r 49 attic code requirements with a single batt. 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. It also suggests r values when adding insulation to uninsulated or under insulated attics crawl spaces and walls.

The table opposite suggests r values by zone as indicated in the map of the united states. 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. X 24 in 6 pieces 48 sq.

Evaluate your house s current r value and recommend whether additional r value is needed and appropriate types of insulation. Input depth of existing blown in insulation in inches. Fill available space with roxul comfortbatts. 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.

References department of energy. Fortunately attic insulation can be upgraded simply by adding more to achieve the recommended total depth in inches without removing existing insulation. You can achieve better thermal performance in your attic by adding an additional layer of insulation. 2 r 23 batts will just fit inside a 2x12 rafter for r 46.