Late last year the Denver City Council approved to amend the City and County of Denver Building and Fire Code (DBC) to adopt the 2018 suite of I-codes along with several local amendments. This is the culmination of an 8-month process that started in May of 2019. With the adoption of the new code, there is a 4-month grace period, until April 2020. During this time, new permits can be submitted under either the 2016 DBC (2015 IECC) or the 2019 DBC (2018 IEC).

Below is a summary of the key changes between the 2015 and 2018 IECC as well as some of the major adopted amendments for the City of Denver.

There are not many differences between the 2015 and 2018 IECC but there are a few changes that will trip you up if you aren’t aware. Currently, OVER 30 municipalities have adopted the 2018 IECC and more are expected to follow.

• Prescriptive Window U-Value Changes – The 2018 IECC reduces the maximum U-Value from .32 to .30.
• Ducts Located in Conditioned Space – The 2018 IECC lays out specific insulation and air sealing requirements for ducts to be considered in conditioned space and including stipulations for ducts in the attic to be modeled as in conditioned space.
• Whole-house mechanical ventilation system fan efficacy – Included ERVs & HRVs into the table that set maximum fan watts per cfm of air moved.
• ERI Compliance Pathway Change – The required ERI moved from a 55 in 2015 to a 61 in 2018.

As part of Denver’s goal to achieve Net Zero New Construction by 2035, multiple amendments were submitted by both outside parties and city staff to start Denver towards that goal. One of the major focuses during this code cycle was to improve efficiency while still maintaining housing affordability. This list covers the major amendments that home builders will need to start preparing for to avoid being caught off guard.

• Grade 1 Insulation – One major amendment is to require Grade 1 Insulation. For batt or loose fill insulation (fiberglass or cellulose) this means that no gaps or voids are allowed and no more than 2% of the total area can have any compressions. This standard is very difficult to achieve with most batt insulation and it may be worthwhile to investigate blown insulation for wall insulation.
• Homeowner Manual– While a common occurrence for most production builders, this amendment requires a binder with all equipment and appliance manufacturer installation instructions. Setting up a system now to collect and store these manuals during the construction process will prevent headaches in the future.
• Floor Cavity Insulation – No additional requirements were added to this section, but the language was significantly changed to allow for easier implementation of floor insulation over unconditioned spaces.
• Air Sealing Testing – No changes in requirements were made but a different metric (CFM per square feet of dwelling unit enclosure or CFM/Sq. Ft) will now be allowed. Small dwelling units under 1000 Sq. Ft. were also allowed into the 4 ACH50 exceptions granted to townhomes. Both these changes will hopefully allow for easier compliance in attached single-family homes and small dwelling units like ADUs.
• Duct Leakage Testing –Under the 2018 IECC there is an exception to testing duct leakage if all ducts are in conditioned space, this amendment removes that exception and requires that all ducts be tested and hit a metric of 6 cfm of leakage per 100 sq. ft of conditioned space. There is an exception for homes that are under 1,200 sq. ft to meet a set requirement.
• Electric Vehicle Charging – This amendment requires that all single-family homes with any dedicated parking space include at least one electric vehicle ready parking space. Along with more stringent requirements for Group-R multifamily occupancies. An electric vehicle ready parking space is defined as “A parking space that is provided with one 40-amp, 208/240-Volt dedicated branch circuit for electric vehicle supply equipment that is terminated at a receptacle, junction box or electric vehicle supply equipment within the parking space.”
• Energy Efficiency Packages – This single amendment is probably the single largest change to the 2018 IECC but is only going to impact the prescriptive compliance pathway. This amendment requires that the builder choose one energy efficiency package from the list as part of compliance. The list includes:
• • Enhanced Envelope Performance
  • More Efficient HVAC Performance
  • High Efficiency in service water heating
  • More Efficient Thermal distribution system
  • Improved air leakage
  • Lighting efficiency
• Adoption of Appendix RA – Appendix RA set solar-ready requirements for all new construction homes included both built-in infrastructure and a requirement for a free area dedicated for future solar.