This information is the most common and is not representative of all the design and submission requirements you may encounter. 

Definitions

• A conditioned space is an area within a building that is heated or cooled or has a fixed opening (no door or closable window) to an area that is heated or cooled.
• A basement wall is more than 50 percent below grade and encloses a conditioned space.
• Glazing is windows, skylights and glass doors.
• An R-value is a measurement of a material’s thermal resistance (the higher, the better).
• A U-factor measures the ability of a material (glass) or assembly (window) to transfer heat (the lower the better).
• A sunroom must meet all of the following conditions:
  • One-story structure added to an existing home.
  • Glazing area exceeds 40 percent of the exterior walls and roof area.
  • Sunroom is served by separate and independently-controlled heating and/or cooling system.
  • Closeable doors and windows separate the sunroom from the rest of the house. 

Design Values 

The table below provides the R-value and U-factor requirements for insulation and glazing, respectively and is based on Climate Zone 5. Higher insulation R-values are permitted provided their dimensions properly fit in the intended cavity without compacting its thickness. Glazing with lower U-factors than required are also permitted. 

Minimum R-Values for Walls/Floors/Ceilings 

¹The first number is for continuously applied insulation, the second is for insulation installed between studs. 
²Insulation must extend form the slab edge to a length of 24 inches vertically and/or horizontally; see figure below. 
³Use insulation on crawl space walls in unvented-conditioned crawl spaces with no floor insulation above.

Determining your own R-values and U-factors?  If you wish to use R-values and U-factors other than those prescribed above, you may manually design your house, addition, or sunroom using RESCheck from the U.S. Department of Energy. Learn more. 

Show Compliance on the Plans 

Clearly indicate on your construction drawings the required R-values and U-factors from the table above or from your RESCheck computation. Upload the RESCheck Compliance Certificate with your construction plans when used.