Building an ADU

[Aidan Birmingham]

I have found a duplex that has about 1250 sqft of an empty land next to it. The lot is zoned as RT4. My idea was to build a single family ADU since I researched that the you need 1200 sqft of land per unit and the lot is .1 acre (4356sqft) so the lot can only allow one more unit.
how much would it roughly cost to build a 2 or 3 bed adu?

[Ko Kashiwagi]

Not aware of how construction cost are looking in Milwaukee, but I'd talk to a couple of contractors/developers in the area. In LA, it can range from 90k-180k depending on who you ask for a ground up ADU. So I have the impression it can really change depending on who you ask.

[Robert Ellis]

Quote from @Ko Kashiwagi:

Not aware of how construction cost are looking in Milwaukee, but I'd talk to a couple of contractors/developers in the area. In LA, it can range from 90k-180k depending on who you ask for a ground up ADU. So I have the impression it can really change depending on who you ask.

 it's not 90k. whoever says that doesn't know how to build. we just built a 668 sq ft house and it was more than that without the land and no garage below it. no way it's that low. 

[Corby Goade]

You need to talk to someone local and defintely get some referrals. In my market, I could easily get quotes ranging from $150ish-$500 per foot, depending on the contractor, their team and specialty and how much of a sucker they thing I am. 

Also, cities and counties are wildly inneficient with this stuff and just because they say you can build an ADU doesn't mean they will actually let you. Before you get too deep, I'd set up a planning meeting with PandZ and get some feedback and direction.

Best of luck!

[Marcus Auerbach]

About $250 to $300 per square foot, because it is small which drives the per sqft cost up absorbing kitchen, bathroom, plumbing, electrical, utilities, basement, roof and impact fees into a small footprint. Bedrooms are cheap.

We will likely see zoning law changes in 2025 for the city of Milwaukee that will lift restrictions on ADU's (google GrowingMKE).

[Aidan Birmingham]

Quote from @Marcus Auerbach:

About $250 to $300 per square foot, because it is small which drives the per sqft cost up absorbing kitchen, bathroom, plumbing, electrical, utilities, basement, roof and impact fees into a small footprint. Bedrooms are cheap.

We will likely see zoning law changes in 2025 for the city of Milwaukee that will lift restrictions on ADU's (google GrowingMKE).

Wow that is way more expensive than I thought. So for a 750 sqft ADU it could cost anywhere from $180,000 to $225,000. The plan was to build an ADU to add sqft, bedrooms, and rent to increase ARV and cash flow but the cost to do so is too high based on the projected return. 

[Whitney Hill]

The reason for the wild swings in bids is: what is considered as part of the scope? The low bids likely don't account for the entire scope of work required to design, permit and build an ADU, including requisite utility upgrades and other site improvements. They may also not account for finishes, or budget appropriately for required permits.

Try googling "Comparing Quotes and Proposals from Different ADU Builders" for a full list of what to look for (I can't link here because it's my own article). You'll also find links to the full list of costs to consider. This will of course vary by jurisdiction, which is why it is crucial to work with a local builder who has actually constructed many ADUs and dealt with the pitfalls on previous projects. Otherwise, you will be their guinea pig and end up with change orders.

[Marcus Auerbach]

Quote from @Aidan Birmingham:

Quote from @Marcus Auerbach:

About $250 to $300 per square foot, because it is small which drives the per sqft cost up absorbing kitchen, bathroom, plumbing, electrical, utilities, basement, roof and impact fees into a small footprint. Bedrooms are cheap.

We will likely see zoning law changes in 2025 for the city of Milwaukee that will lift restrictions on ADU's (google GrowingMKE).

Wow that is way more expensive than I thought. So for a 750 sqft ADU it could cost anywhere from $180,000 to $225,000. The plan was to build an ADU to add sqft, bedrooms, and rent to increase ARV and cash flow but the cost to do so is too high based on the projected return. 

Yup, pretty much. The cost per sqft goes down as you increase square footage. 1000 to 1200 is the sweet spot. Just look at your insurance policy, if you have insured the duplex for replacement value (and not for cost) it will show something like 400-500k.