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Detached ADU w/ utility basement accessory to main house

ElNaf22

Registered User
Joined
Mar 26, 2020
Messages
3
Location
Eugene, OR
Working under ORSC 2017, we have a detached ADU with a full-height basement that will be used by the main house for gardening type supplies. The plans checker is asking who the primary user of the space will be (or if it will be common space), and to address fire-rated construction per 302.3. My original intent was a layer of 5/8" Type X at the ceiling (per 302.6) like a normal garage, but it seems he's angling toward a dwelling unit separation even though the main house is 30' away. I'm not finding code info on common space separations. Thoughts?
 
?????

New Construction and Additions. When an ADU is constructed as an addition or separate detached accessory structure, the construction shall comply with the requirements of the Oregon Residential Specialty Code as a two-family dwelling and the City Development Code.

1/2 inch required??



In areas of the basement with exposed ceilings (see plans), the existing floor assembly does not meet the exact minimum code per BDS/ADU Program Guide which requires a minimum of 1/2" gypsum board applied to the underside of the floor system.
 
How is the basement accessed? Is the basement a daylight basement? Is there any interior connection between the basement and the ADU upstairs? If not, then does it really matter who will use it? Since you did not say the basement was a dwelling unit, then the dwelling unit separation requirement of R302.3 does not apply.

However, if the basement were plumbed and wired to easily convert into another dwelling unit, the the plans examiner has better reason to require a 1 hour floor/separation between the 2.

FYI, Oregon has kept the same verbiage from 2017 ORSC requirement in the newly adopted 2021 ORSC.
 
Thank you all for your responses. The basement will be accessed from an exterior concrete stairwell but otherwise is fully underground with no interior connection. The jurisdiction is Portland BDS. The basement is not plumbed or wired. I agree that R302.3 doesn't seem applicable, which is why I was confused when it showed up in the plan comment. The initial submittal noted the basement was unheated storage accessory to the main house.
 
Copy the definition back to them, and say

Not a dwelling unit ,, 302.3 does not apply

see what they say

[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.

Or how much does dry walling add to the price?? Plus looks prettier!!
 
How is the basement accessed? Is the basement a daylight basement? Is there any interior connection between the basement and the ADU upstairs? If not, then does it really matter who will use it? Since you did not say the basement was a dwelling unit, then the dwelling unit separation requirement of R302.3 does not apply.

However, if the basement were plumbed and wired to easily convert into another dwelling unit, the the plans examiner has better reason to require a 1 hour floor/separation between the 2.

FYI, Oregon has kept the same verbiage from 2017 ORSC requirement in the newly adopted 2021 ORSC.
My thoughts too....Not a dwelling unit and not "common" space....Although I can see where the reviewer is coming from protecting the one "tenant" from the other.....When they store the lawnmowers and gas and LP under that unit....
 
Although I can see where the reviewer is coming from protecting the one "tenant" from the other.....When they store the lawnmowers and gas and LP under that unit....
I like that train of thought. Who knows what else they end up doing down there. I can picture the calls to code enforcement, "I think my landlord is doing .......... downstairs." It would also be nice if there were a separate feeder for some lights and convenience outlets that are fed from the main house. Unless they plan on including electricity in the rent. They might not plan on having any electricity, but once they're going in and out of there without a light, or wanting to charge a power tool they're likely to think "but there's power right here, I can just tap off of this and they'll never know, besides I hardly use any electricity anyways." Way too common.
 
Those are good points. I definitely want at least 5/8" Type X at the ceiling (the walls are concrete). I imagine the owner won't want to run a feed all the way from the main house, but the electricity usage would be minimal if he did tap off the ADU. He has other sheds on the property for mowers and such (hauling one up and down the basement stairs would be a pain) so I don't expect that would be stored there.
 
Expectations are one thing, but all good intentions go out the window when a HO decides "this is no big deal." A homeowner deciding to tap off of a tenants power for personal use is highly unethical, not to mention potentially illegal, regardless of how little electricity is used. I have personal and recent experience with this. I rented a small house that was built over two separate garages, one for the tenant and one for her. When I signed the lease I was told clearly that the utilities for her garage were tapped independently from her house which was true for the water and gas, but it turned out the lights and outlets were run off of the ADU meter. I suspected this initially and shortly after moving in I decided to turn some breakers off while she had a "handyman" running some tools (table saw, miter saw, etc...). Sure enough the saw cut out when I flipped the breaker. He got real mad and up in my face, I said "give her a call." She came back a few minutes later all red in the face and said "I told the electrician to wire it separately," playing dumb doesn't go over well with me. I refused to turn the breaker back on without a written agreement that she would fix it. She didn't, I broke the lease and moved out. Most people would never know or suspect this and it is very common.

I would recommend advising your client of the ethical and potentially legal issues involved with tapping off a tenants power.
 
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