• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Must attached ADU's be separated by a door?

C

codehelpneeded

REGISTERED
Joined
Dec 10, 2024
Messages
9
Location
WA
Must an attached ADU be separated from the primary residence by a door? If so, should it lock? If so, who should be able to lock the door? The Building and Planning Departments that I work for are debating this. The ADU would have its own main egress door elsewhere. The door in question would be located at the bottom of a flight of stairs from the primary unit upstairs.

Washington State
2021 I-codes
 
In my opinion, planning and land use codes muck things up quite a bit. The term ADU comes out of land use codes designed to create more housing. In building code, dwelling units are required to have a fire separation. The residential code says: "Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than..." I have heard the argument that a fire rated door could be considered part of a wall assembly, but I don't buy that. The residential code defines:

[RB] DWELLING UNIT. A single unit providing complete
independent living facilities for one or more persons, including
permanent provisions for living, sleeping, eating, cooking
and sanitation.

I argue that if there's a door between the two units, they are not providing "complete independent living". California attempted to solve this dilemma by creating Junior ADU's. These are allowed to share parts of the house (such as a laundry room) but still be considered a separate unit. In my opinion, there are not truly separate dwellings, they are part of the same unit.
 
steveray said:
If there is no door, it is either a two family dwelling or not an ADU really....
Click to expand...
It all comes down to state planning and land use laws right? I've heard other states treat them differently than we do. I tend to ignore the term when discussing building code requirements. I don't care what you call it, ADU, Mother-in-Law, granny-flat, etc. It's either a separate dwelling unit or it's not. If it is, then code dictates separation requirements.

In CA they added this definition to the residential code:

ACCESSORY DWELLING UNIT. [HCD 1 & HCD 2] An
attached or detached residential dwelling unit that provides
complete independent living facilities for one or more persons
and is located on a lot with a proposed or existing primary
residence. Accessory dwelling units shall include
permanent provisions for living, sleeping, eating, cooking
and sanitation on the same parcel as the single-family or
multifamily dwelling is or will be situated. (See Government
Code Section 65852.2)
 
This seems to be more of a zoning code issue than a residential building code issue. Looking at the purpose of ADUs as they are coming into use in various parts of the country, it seems clear to me (wearing my architect and one-time zoning commissioner hats) that the intent is for an ADU to be a separate dwelling unit on the same parcel. As a separate dwelling unit, it might be a detached structure or it might be an attached structure, but it's supposed to be a seoparate dwelling unit, intended for occupancy by a different person or family than the occupants of the primary dwelling unit on the parcel.

Based on that, my view is that there should not be any interior communication between the primary dwelling unit and the ADU.
 
Thanks for the responses. ADU's have a max square footage. It's hard to measure square feet when there is no door or wall separating the units. WA also does not require any type of fire separation between the primary and ADU. It also seems like the door should be weather-stripped for noise and smells.
 
You must log in or register to reply here.
Back
Top