As more states embrace Accessory Dwelling Units (ADUs) (why is there a hyperlink?) as part of their housing solution, many homeowners are jumping into adding a second or third unit to their homes, thinking it is a straightforward renovation. However, adding additional units often trigger costly improvements related to fire protection and life safety.   
  

Depending on where you live and the potential use of the additional unit, there are significant triggers, including:  

• Change of Use Can Trigger Major Fire Protection Requirements 
  If you are converting a two-family home to a three-family home, that is called a “change of use” and often triggers requirements for fire protection (sprinkler) systems in the ADU and fire alarm systems throughout the home.  

• Short-Term Rentals May Require Additional Fire Safety Upgrades 
  Depending on the use of the space (e.g. short-term rental) and where you live, even if you are changing a single-family home to a two-family home, you may need to add a sprinkler system.   

• Means of Egress: A Second Exit May Be Required 
  If the unit will be on a level other than the ground level, additional means of egress requirements may apply. Depending on the location, occupancy classification, and design of the space, a second exit or additional emergency escape and rescue opening may be required. Many upper-level or basement spaces have only one way out, making egress compliance a significant consideration when creating an ADU. 

Depending on the design of the space and the required level of upgrades, costs associated with sprinklers, fire alarms, egress improvements, and utility modifications can quickly add up. In some projects, these additional requirements may increase the budget by tens of thousands of dollars. Suddenly, that projected rental income starts looking less like a quick revenue stream and more like a patient long-term investment. 

At the end of the day, ADUs are absolutely worth exploring—but they are not always the simple “extra apartment” many people imagine. It is critical to understand these potential costs before you go too far down the path and start spending money on design and construction, only to find out during permitting or inspection that there is an issue.   

At the end of the day, ADUs are absolutely worth exploring—but they are not always the simple “extra apartment” many people imagine. Understanding the potential code and life safety implications before construction begins can help avoid costly surprises later in the project. 

At Jigsaw Life Safety, we assist homeowners, architects, and developers with code analyses, fire protection and fire alarm system design to help navigate the requirements associated with ADU projects. Contact us before adding an ADU to your existing property at 617.351.9600 or support@jigsawlifesafety.com.