• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Townhome or Duplex w/ ADU?

MEP

Registered User
Joined
Mar 25, 2022
Messages
3
Location
Northern California
I have a project that is proposing a duplex with (2) attached ADU's, one on each side. There will be a property line separating the structure into (2) halfplexes, each with an ADU. Since there are (4) attached units, would this be considered a townhouse by definition? Or could it be reviewed as a two-family dwelling (with an ADU)?

"[RB] TOWNHOUSE. A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or public way on not less than two sides."

Going further down the rabbit hole, would it also be considered a covered multifamily dwelling?

COVERED MULTIFAMILY DWELLINGS. [HCD 1-AC] "Covered multifamily dwellings" means either of the following:
  1. Buildings that consist of at least four condominium dwelling units or at least three apartment dwelling units if the buildings have at least one elevator.
  2. The ground floor dwelling units in buildings that consist of at least four condominium dwelling units or at least three apartment dwelling units if the building does not have an elevator.
Covered multifamily dwellings include dwellings listed in Section 1102A.1. For purposes of this definition, dwelling units within a single structure separated by firewalls do not constitute separate buildings.

I understand it is CA's intention to encourage ADUs, so I am not sure if the accessory unit would count toward the townhome definition. But, it IS still a unit. Main considerations are structural independence and fire separation. I am still investigating the ownership structure, but any input would be helpful.
 
Given the description provided and property line, I would be suggest that each property has a townhouse with ADU. Question: Is the ADU configuration conflict with the townhouse definition (i.e., each unit extends from foundation to roof and is open on two sides)?
 
I thought an ADU was a separate item, like a converted detached garage. If it's attached to the main duplex building, is it really an ADU?
 
Given the description provided and property line, I would be suggest that each property has a townhouse with ADU. Question: Is the ADU configuration conflict with the townhouse definition (i.e., each unit extends from foundation to roof and is open on two sides)?
A portion of the ADU is under the primary, so technically the unit does not extend from foundation. If it is not technically a townhouse or a two family dwelling I suppose design and requirements would be per CBC?
 
Does CBC 11A Housing Accessibility Standards apply to single-family dwellings or duplexes?
NO

It does apply to Apartment buildings with 3 or more dwelling units and Condominiums with 4 or more dwelling units
 
This sounds like a condominium arrangement. If it were townhouse there would be a minimum of three units with only one classified as an ADU. As a condominium the attached ADU will forever remain under the same ownership as the condominium that it is attached to. Unless the rules have changed, the property owner has to live on the property when an ADU is present. However that's a rule that is impossible to enforce so it may have gone away.
 
Top