2012 BUILDING CODE UPDATE
Teton County has adopted the 2012 International Residential Building Code. There are several changes in the insulation requirements. The new code requires the following changes to the insulation, air sealing, duct sealing, mechanical ventilation, and heating/cooling equipment sizing. At first glance these requirements may seem to be a costly requirement, however the code is broad enough that these items may have very little impact on construction costs. Here is a quick outline of the new requirements -
INSULATION: The new code allows for two different methods to meet code. The first is the Simplified Method, where each component in the exterior shell meets the requirements of table N1102.1.1, which for our climate requires windows to have a U-factor of .32. Ceiling insulation is R-49. Exterior walls require an R-5 of rigid board on the exterior walls with an R-20 cavity fill. Crawlspace floors are R-38. Below grade basement walls and crawlspace walls are R-15 of continuous insulation, or R-19 of cavity insulation. The big change in the simplified method is installing the exterior rigid board.
The second method is for using a Performance Based Compliance program. There are several different types of programs available. Probably the simplest one to use is called REScheck. Once the square footage of the walls, ceiling, floor, windows, and doors are entered into a model, different insulating values can be entered. It is fairly easy to meet or exceed the insulation requirements without installing the rigid board on most buildings. In fact, most of the buildings constructed in Teton County will exceed the 2012 code requirements based on the Performance Based approach without using the exterior rigid board. (We have attached a REScheck example.)
With few exceptions, we do not foresee the need for exterior rigid board if using a performance-based design.
AIR SEALING: The new code requires that buildings do not exceed 3 air changes per hour in our climate. This needs to be verified with a blower door test. Depending on the types of insulation used, air sealing can be accomplished several ways. If spray foam is used, air sealing is as simple as just caulking the framing. If fibrous insulations are used, air sealing can be done by sealing the house wrap material or by sealing the drywall. If using fibrous insulations, airtight electrical boxes should be used. The 2012 code requires that all IC lights be of airtight construction.
Air sealing should be pre-planned as to what system will be the air barrier so that it can be properly installed during the various stages of construction.
DUCT SEALING: The 2012 code requires that ducts, air handlers, and filter boxes be sealed. If the ducting and air handlers are located within a conditioned space they are not required to be sealed.
MECHANICAL VENTILATION: The 2012 code requires a whole house mechanical ventilition system. These systems can be smaller, non-heat recovery units or they can be heat recovery units. The code lists a chart for the fan efficacy of bathroom and range hood fans. Providing a home with a controlled fresh air supply provides the occupants with a lifetime of air quality benefits.
HEATING AND COOLOING EQUIPMENT: The 2012 code requires that the heating equipment shall be sized based on building loads. This could result in a potentially large cost savings from the use of smaller HVAC units.
As with everything, there will be a learning curve for everyone as the new code is intergrated. Given that most homes built in Teton County already exceed the engery code, there should not be too much of an impact in construction costs when implementing the 2012 code.
Enclosed is a copy of sections of Chapter 11, Energy Efficiency, of 2012 International Residential Building Code. Please refer to page 485 – Table N122.214.171.124 that outlines the insulation and air barrier requirements for the 2012 code. Teton County’s website has a link to the entire 2012 code, which can be found at http://www.tetonwyo.org/pdbldg.
Attached is an example of REScheck.
This example is for a 5,000 sq. ft. house with 37% windows. Note that both the 2006 and 2012 requirements are identical as far as insulation values. The only difference in this example is the U-factor of the windows: .35 for 2006, and .32 for 2012. Also note that this home is considered .8% better, or more efficient, than the 2012 minimum requirements.