Many states have adopted the 2009 International Energy Conservation Code (IECC); some have even migrated to the 2012 version. They are both very good codes, significantly improving the energy performance of new buildings, but unfortunately, their effect on existing buildings is limited.

The code only applies to those parts of additions and renovations that are either entirely new or that expose the insulation or the empty insulation cavities. New areas must meet the code minimums, and existing exposed framing cavities must either be filled with enough insulation to meet the code or filled with as much insulation as will fit.

So, though the existing part of a remodeling project doesn’t have to comply with current codes, you can use them as a guide to create a better building, lower energy use, and make homeowners more comfortable.

The Envelope, Please

The most useful part of the IECC is the table of required air sealing measures (Table 402.4.2 in the 2009 version), which offers good standards for creating a solid building envelope, starting with a requirement that the insulation is installed in contact and aligned with the air barrier. Other requirements:

• insulated wall corners and headers;

• air-sealed and insulated rim joists;

• insulation cut and fit around wires and pipes (think of that!); and

• HVAC boots sealed to drywall and floors.

If you are doing an addition to a house, this is, at least theoretically, all required in the new construction areas, provided the inspectors actually enforce it. But nothing has to be done to the existing parts of the building that aren’t gutted. So, in most cases, you end up with (hopefully) an efficient addition, usually attached to a poorly performing existing building.


Air sealing can be labor-intensive, but it makes a home much more efficient and comfortable. Though it would be challenging, expensive, and in some cases impossible to upgrade an existing structure to the current energy code, there are inexpensive things you can do that provide significant value:

• Caulk around windows, doors, and interior baseboards when painting and finishing floors.

• Caulk gaps around pipes and wires in top and bottom plates and then install extra ceiling insulation.

• Install solid blocking at the top and bottom of mechanical chases between floors, at dropped soffits, and behind attic knee walls.

• Have your painter caulk HVAC boots — he probably won’t charge you much, if anything, to do it.

Using the new energy code as a guide for existing buildings helps your clients save energy and be more comfortable — things that can lead to referrals.

PDF Resources

• Georgia State Energy Code Amendments has an excellent set of drawings showing how to insulate and air seal.

• Chapter 4 of our book, Insulation and Air Sealing, is available for free download from the publisher.

—Carl Seville teaches, speaks, and writes about, consults on, and certifies green buildings. He is co-author of Green Building: Principles and Practices in Residential Construction.;