What are you building costs for ADU's?

Question

Hey everyone!

This is mainly for those who have recently built or got contractor/builder quotes for building an ADU. I am curious as to what your are finding the current building costs are?

I am working on putting together a building system to be around $150/sf hard costs for a build. The idea is to systemize the process and be able to offer a good quality product for a lower price than is generally available, and still make a decent profit. And we would start with building ADU's, since that seems readily systemizable and a popular trend with good demand.

So, does $150/sf sound attractive to you if you were in the market to build an ADU?  between 800sf-1,200sf

I am mostly looking for California opinions, but all are welcome. TIA

I am also posting this under other categories, so I apologize for the redundancy.

Bruce Woodruff · Answer

I just don't see how you get 'er done for $150 SF. I was bidding these out higher than that back when they first became a big thing in San Diego (Around 2018). The city was already giving out pre-approved plans which saved a lot of time, money and hassle...but building costs are what they are. Plus the special 'alleged green' requirements for CA were costly (mandatory mini-splits, special insulation, tankless WH, etc)

I'd be curious what you could net as a builder even with a system(s) in place. I'd bet it will be higher than $250 SF in todays market. And these are not all that attractoive for a builder anyway...kinda something to do when you're slow...

Scott E. · Answer

Remodeling / Rebuilding an existing house is going to be cheaper per foot than new construction.

If you're building an ADU you're going to need things like..

1. Probably some site work/grading

2. A new slab

3. New sewer line ran to the unit (or septic)

4. New electrical panel

5. Water lines run from main to ADU

6. Not to mention all new framing, insulation, roof, drywall, HVAC system, wiring, rough plumbing, etc etc.

Not trying to discourage you. Just outlining a few reasons why you might discover that your $150/SF number is unrealistic.

Scott E. · Answer

Yes $150/sf sounds very attractive, but I agree with Bruce. $250 is much more realistic. Even if you're building the thing yourself you're going to have a hard time building for $150/sf.

Scott E. · Answer

Just caught this after I made my last post. So funny... my first new construction spec build was in 2017. It was slightly larger at 2,872 square feet. But I built the thing for under $500k. Less than $175/SF. And this home was decked out with very nice, high end, custom finishes.

In hindsight I wish I had built 10 of them at that price. 2017 was a loooooong time ago. And times have changed...

Alex U. · Answer

So one interesting thing to note, when contractors throw around numbres of $sq/ft.  It actually does not make much sense.  For example, take a look at Snap ADU ( https://snapadu.com/adu-floor-plans-1-bedroom/) . Here are 2 1/1 floor plans

1/1 - 425 sq ft = $529 sq ft 425 sq ft, $225,000

1/1 - 993 sq ft = $342 sq/ft 993 sq ft $340,000

If you are building multiple units lets say 4-20, the $/sq ft makes absolutely no sense at all.

Tim Seims · Answer

https://www.dwellito.com/adu-cost-calculator

Dan H. · Answer

I suspect you know this but 1) prices have risen a lot since 2019 2) smaller sf development has higher cost per sf due to various “fixed” costs and minimum work quotes.   How many SF was that house built in 2019?  I suspect it was bigger than 1200’.

Good luck

Brad S. · Answer

Thanks Scott! I appreciate the reply!

Yeah, I know this is going to be a challenge, but I do feel there is a big opportunity to find alternative ways to keep build costs down these days. Costs have skyrocketed for basic builds. I rebuilt my own house in 2019 for around $175/sf, so I totally get it, but I am up for the challenge!

Alex U. · Answer

If you want to get down to $150, one has to manage the project entirely.  With rising interest rates, rents are getting squashed as the cost of capital is becoming too high for construction (12% construction loans).  This will trickle down to the build side, and GC will have to start settling for $250/ft and less.  Give it 6-12 months, and I think we see prices coming back down to earth, as the Fed keeps rates very high.

Does anyone know of a basic construction calculator or Work Breakdown structure?  It would be great to enter total sq footage, number of bathrooms, linear feet of kitchen, and finish quality( low, med, high) and get a breakdown of labor and material, roughly speaking.

For example- 8" foundation, $/per sq ft

- Framing $/sq ft

-no of bathrooms/kitchens cost of rough plumbing

-rough electrical

etc etc etc

Tim Seims · Answer

Not sure how helpful but I work with a lot of modular manufacturers for ADU. Mostly I consult on their go-to-market strategy. So I've learned they average $300-450 turnkey with their contractors. But most deliveries are to a person that has their own GC or are self-build.They big variables are permits, site work, utilities. If you want to go this way, ask your GC about their prefab experience. Some prefab manufacturers offer training for licensed contractors.Most prefab mfrs require deposit and the unit to be 100% paid for when it ships to your job. Most often they can help you find financing.

You might want to consult with an adu expert like Kol Peterson, or Derek Sherrell.

That ADU Guy on youtube covers a lot on cost, he does much of the work himself, and targets a $100k, 100 day build. Julee Felsman on youtube goes through more ADU finance options

What are you building costs for ADU's?

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