Building a detached ADU in Tacoma

5 Replies

Currently wrapping up framing, about to start roof and exterior siding. There have been a lot of challenges and extra costs, not planned for. Anyone else working on an ADU, or thinking about it? Want to share ideas? Let me know.

@Tim S.

Hey Tim I am currently about 90 percent finished with the drafting process for my own ADU. Still no property but working on the process. I would be interested to see what your total sqft price is at for building.

That being said I am a builder in the area s I if ypu ate looking for another contractor that has low overhead (therefore can be quite competitive). Hit me up I am prospecting for buisiness partners who I can leverage my sweat equity with to get some rentals going. I also could just direct you to some other subs just to make sure your prices are fair. Always good to get multiple bids.

@Nicholas Rickman ,  Well, we'll see where it ends up in terms of cost.  There have been several sizable change orders bumping up the price, and there could be more.  It's 830 sqft. Hope to end up around $160k for construction.  That doesn't include design, or permits, I'm up to about $16k for those items.  I have a GC running the job, so he's providing all of the subs.  I can get outside quotes if I need to. I did on the trench I talk about below. 

A couple of surprises, I was not able to bring power from the main house, it is maxed out. New service needs to be added from the pole. Existing service is above ground wires, over 2 adjacent properties to the house. Tacoma Power says they don't have right of way to add service that way over 2 properties. So I had to dig a 150' trench from the pole, down the alley to the ADU. That was pretty expensive, $2300 to Tacoma Power, and another $6.5k for the trench.

2nd issue, a fire sprinkler system is required since part of the structure is >150" from the street.  That wasn't in the original quote, and added about $8k. 

Had a couple of design issues from the architect, that caused some delays.  Most important is the overall height, which is close to the max limit.  Couldn't be built at the elevation the architect showed on the original prints due to lay of the land.  We had to stop construction and get confirmation that the increased height would be OK.  Took 2 weeks to get city approval.

Material delays due to COVID and wild fires.  Had to wait 6 weeks for trusses. It's good to have someone local to bounce things off of.  It's hard to manage this from afar, we were up there this weekend to see the progress for the first time. Glad to be in touch with you. 

Hi, Tim - we're working on a garage (detached) conversion to ADU in far northern CA. Our garage was used at one time as living quarters so it actually had a bathroom and therefore sewer connection, and water and power to the building. We're in City limits and have a great relationship with the building dept so they've been able to help us strategize about what needs to be done to be fully compliant and hopefully avoid issues you've run into like surprises about your sprinkler system and building height. We will be running a separate meter to the building because we want tenants to be responsible for their own utilities. We have a foundation and will be able to save most of the walls. Roof needs to be replaced and it's a full gut remodel of 600 sq. ft. Our architect will charge about $1500-1800 for plans. We estimate about $35-38k all in, but again, we're working with an existing structure and already have sewer, water and power (though we need to add the meter.) We're also saving a lot on new build fees since we're working with an existing structure. We're actually targeting properties with an existing structure that can be converted to an ADU because the build-from-scratch option doesn't seem to pencil, at least not at our rental rates.

@Tim S.

Ya definitely keep in touch especially for future projects in the area. Thanks for the info.

My Target cost is under 100 dollars pft. I obviously have the benifit of being able to do all the work I want and sub the rest.

I know there are some builders that build for 90 dollars a ft. But with the rise in materials that is probably not the case. Good luck don't be shy if I can help hit me up.